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1 /*
2  *  linux/mm/memory.c
3  *
4  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
5  */
6
7 /*
8  * demand-loading started 01.12.91 - seems it is high on the list of
9  * things wanted, and it should be easy to implement. - Linus
10  */
11
12 /*
13  * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14  * pages started 02.12.91, seems to work. - Linus.
15  *
16  * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17  * would have taken more than the 6M I have free, but it worked well as
18  * far as I could see.
19  *
20  * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21  */
22
23 /*
24  * Real VM (paging to/from disk) started 18.12.91. Much more work and
25  * thought has to go into this. Oh, well..
26  * 19.12.91  -  works, somewhat. Sometimes I get faults, don't know why.
27  *              Found it. Everything seems to work now.
28  * 20.12.91  -  Ok, making the swap-device changeable like the root.
29  */
30
31 /*
32  * 05.04.94  -  Multi-page memory management added for v1.1.
33  *              Idea by Alex Bligh (alex@cconcepts.co.uk)
34  *
35  * 16.07.99  -  Support of BIGMEM added by Gerhard Wichert, Siemens AG
36  *              (Gerhard.Wichert@pdb.siemens.de)
37  *
38  * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39  */
40
41 #include <linux/kernel_stat.h>
42 #include <linux/mm.h>
43 #include <linux/sched/mm.h>
44 #include <linux/sched/coredump.h>
45 #include <linux/sched/numa_balancing.h>
46 #include <linux/sched/task.h>
47 #include <linux/hugetlb.h>
48 #include <linux/mman.h>
49 #include <linux/swap.h>
50 #include <linux/highmem.h>
51 #include <linux/pagemap.h>
52 #include <linux/ksm.h>
53 #include <linux/rmap.h>
54 #include <linux/export.h>
55 #include <linux/delayacct.h>
56 #include <linux/init.h>
57 #include <linux/pfn_t.h>
58 #include <linux/writeback.h>
59 #include <linux/memcontrol.h>
60 #include <linux/mmu_notifier.h>
61 #include <linux/kallsyms.h>
62 #include <linux/swapops.h>
63 #include <linux/elf.h>
64 #include <linux/gfp.h>
65 #include <linux/migrate.h>
66 #include <linux/string.h>
67 #include <linux/dma-debug.h>
68 #include <linux/debugfs.h>
69 #include <linux/userfaultfd_k.h>
70 #include <linux/dax.h>
71
72 #include <asm/io.h>
73 #include <asm/mmu_context.h>
74 #include <asm/pgalloc.h>
75 #include <linux/uaccess.h>
76 #include <asm/tlb.h>
77 #include <asm/tlbflush.h>
78 #include <asm/pgtable.h>
79
80 #include "internal.h"
81
82 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
83 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
84 #endif
85
86 #ifndef CONFIG_NEED_MULTIPLE_NODES
87 /* use the per-pgdat data instead for discontigmem - mbligh */
88 unsigned long max_mapnr;
89 EXPORT_SYMBOL(max_mapnr);
90
91 struct page *mem_map;
92 EXPORT_SYMBOL(mem_map);
93 #endif
94
95 /*
96  * A number of key systems in x86 including ioremap() rely on the assumption
97  * that high_memory defines the upper bound on direct map memory, then end
98  * of ZONE_NORMAL.  Under CONFIG_DISCONTIG this means that max_low_pfn and
99  * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
100  * and ZONE_HIGHMEM.
101  */
102 void *high_memory;
103 EXPORT_SYMBOL(high_memory);
104
105 /*
106  * Randomize the address space (stacks, mmaps, brk, etc.).
107  *
108  * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
109  *   as ancient (libc5 based) binaries can segfault. )
110  */
111 int randomize_va_space __read_mostly =
112 #ifdef CONFIG_COMPAT_BRK
113                                         1;
114 #else
115                                         2;
116 #endif
117
118 static int __init disable_randmaps(char *s)
119 {
120         randomize_va_space = 0;
121         return 1;
122 }
123 __setup("norandmaps", disable_randmaps);
124
125 unsigned long zero_pfn __read_mostly;
126 EXPORT_SYMBOL(zero_pfn);
127
128 unsigned long highest_memmap_pfn __read_mostly;
129
130 /*
131  * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
132  */
133 static int __init init_zero_pfn(void)
134 {
135         zero_pfn = page_to_pfn(ZERO_PAGE(0));
136         return 0;
137 }
138 core_initcall(init_zero_pfn);
139
140
141 #if defined(SPLIT_RSS_COUNTING)
142
143 void sync_mm_rss(struct mm_struct *mm)
144 {
145         int i;
146
147         for (i = 0; i < NR_MM_COUNTERS; i++) {
148                 if (current->rss_stat.count[i]) {
149                         add_mm_counter(mm, i, current->rss_stat.count[i]);
150                         current->rss_stat.count[i] = 0;
151                 }
152         }
153         current->rss_stat.events = 0;
154 }
155
156 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
157 {
158         struct task_struct *task = current;
159
160         if (likely(task->mm == mm))
161                 task->rss_stat.count[member] += val;
162         else
163                 add_mm_counter(mm, member, val);
164 }
165 #define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
166 #define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
167
168 /* sync counter once per 64 page faults */
169 #define TASK_RSS_EVENTS_THRESH  (64)
170 static void check_sync_rss_stat(struct task_struct *task)
171 {
172         if (unlikely(task != current))
173                 return;
174         if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
175                 sync_mm_rss(task->mm);
176 }
177 #else /* SPLIT_RSS_COUNTING */
178
179 #define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
180 #define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
181
182 static void check_sync_rss_stat(struct task_struct *task)
183 {
184 }
185
186 #endif /* SPLIT_RSS_COUNTING */
187
188 #ifdef HAVE_GENERIC_MMU_GATHER
189
190 static bool tlb_next_batch(struct mmu_gather *tlb)
191 {
192         struct mmu_gather_batch *batch;
193
194         batch = tlb->active;
195         if (batch->next) {
196                 tlb->active = batch->next;
197                 return true;
198         }
199
200         if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
201                 return false;
202
203         batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
204         if (!batch)
205                 return false;
206
207         tlb->batch_count++;
208         batch->next = NULL;
209         batch->nr   = 0;
210         batch->max  = MAX_GATHER_BATCH;
211
212         tlb->active->next = batch;
213         tlb->active = batch;
214
215         return true;
216 }
217
218 /* tlb_gather_mmu
219  *      Called to initialize an (on-stack) mmu_gather structure for page-table
220  *      tear-down from @mm. The @fullmm argument is used when @mm is without
221  *      users and we're going to destroy the full address space (exit/execve).
222  */
223 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
224 {
225         tlb->mm = mm;
226
227         /* Is it from 0 to ~0? */
228         tlb->fullmm     = !(start | (end+1));
229         tlb->need_flush_all = 0;
230         tlb->local.next = NULL;
231         tlb->local.nr   = 0;
232         tlb->local.max  = ARRAY_SIZE(tlb->__pages);
233         tlb->active     = &tlb->local;
234         tlb->batch_count = 0;
235
236 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
237         tlb->batch = NULL;
238 #endif
239         tlb->page_size = 0;
240
241         __tlb_reset_range(tlb);
242 }
243
244 static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
245 {
246         if (!tlb->end)
247                 return;
248
249         tlb_flush(tlb);
250         mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
251 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
252         tlb_table_flush(tlb);
253 #endif
254         __tlb_reset_range(tlb);
255 }
256
257 static void tlb_flush_mmu_free(struct mmu_gather *tlb)
258 {
259         struct mmu_gather_batch *batch;
260
261         for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
262                 free_pages_and_swap_cache(batch->pages, batch->nr);
263                 batch->nr = 0;
264         }
265         tlb->active = &tlb->local;
266 }
267
268 void tlb_flush_mmu(struct mmu_gather *tlb)
269 {
270         tlb_flush_mmu_tlbonly(tlb);
271         tlb_flush_mmu_free(tlb);
272 }
273
274 /* tlb_finish_mmu
275  *      Called at the end of the shootdown operation to free up any resources
276  *      that were required.
277  */
278 void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
279 {
280         struct mmu_gather_batch *batch, *next;
281
282         tlb_flush_mmu(tlb);
283
284         /* keep the page table cache within bounds */
285         check_pgt_cache();
286
287         for (batch = tlb->local.next; batch; batch = next) {
288                 next = batch->next;
289                 free_pages((unsigned long)batch, 0);
290         }
291         tlb->local.next = NULL;
292 }
293
294 /* __tlb_remove_page
295  *      Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
296  *      handling the additional races in SMP caused by other CPUs caching valid
297  *      mappings in their TLBs. Returns the number of free page slots left.
298  *      When out of page slots we must call tlb_flush_mmu().
299  *returns true if the caller should flush.
300  */
301 bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size)
302 {
303         struct mmu_gather_batch *batch;
304
305         VM_BUG_ON(!tlb->end);
306         VM_WARN_ON(tlb->page_size != page_size);
307
308         batch = tlb->active;
309         /*
310          * Add the page and check if we are full. If so
311          * force a flush.
312          */
313         batch->pages[batch->nr++] = page;
314         if (batch->nr == batch->max) {
315                 if (!tlb_next_batch(tlb))
316                         return true;
317                 batch = tlb->active;
318         }
319         VM_BUG_ON_PAGE(batch->nr > batch->max, page);
320
321         return false;
322 }
323
324 #endif /* HAVE_GENERIC_MMU_GATHER */
325
326 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
327
328 /*
329  * See the comment near struct mmu_table_batch.
330  */
331
332 static void tlb_remove_table_smp_sync(void *arg)
333 {
334         /* Simply deliver the interrupt */
335 }
336
337 static void tlb_remove_table_one(void *table)
338 {
339         /*
340          * This isn't an RCU grace period and hence the page-tables cannot be
341          * assumed to be actually RCU-freed.
342          *
343          * It is however sufficient for software page-table walkers that rely on
344          * IRQ disabling. See the comment near struct mmu_table_batch.
345          */
346         smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
347         __tlb_remove_table(table);
348 }
349
350 static void tlb_remove_table_rcu(struct rcu_head *head)
351 {
352         struct mmu_table_batch *batch;
353         int i;
354
355         batch = container_of(head, struct mmu_table_batch, rcu);
356
357         for (i = 0; i < batch->nr; i++)
358                 __tlb_remove_table(batch->tables[i]);
359
360         free_page((unsigned long)batch);
361 }
362
363 void tlb_table_flush(struct mmu_gather *tlb)
364 {
365         struct mmu_table_batch **batch = &tlb->batch;
366
367         if (*batch) {
368                 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
369                 *batch = NULL;
370         }
371 }
372
373 void tlb_remove_table(struct mmu_gather *tlb, void *table)
374 {
375         struct mmu_table_batch **batch = &tlb->batch;
376
377         /*
378          * When there's less then two users of this mm there cannot be a
379          * concurrent page-table walk.
380          */
381         if (atomic_read(&tlb->mm->mm_users) < 2) {
382                 __tlb_remove_table(table);
383                 return;
384         }
385
386         if (*batch == NULL) {
387                 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
388                 if (*batch == NULL) {
389                         tlb_remove_table_one(table);
390                         return;
391                 }
392                 (*batch)->nr = 0;
393         }
394         (*batch)->tables[(*batch)->nr++] = table;
395         if ((*batch)->nr == MAX_TABLE_BATCH)
396                 tlb_table_flush(tlb);
397 }
398
399 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
400
401 /*
402  * Note: this doesn't free the actual pages themselves. That
403  * has been handled earlier when unmapping all the memory regions.
404  */
405 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
406                            unsigned long addr)
407 {
408         pgtable_t token = pmd_pgtable(*pmd);
409         pmd_clear(pmd);
410         pte_free_tlb(tlb, token, addr);
411         atomic_long_dec(&tlb->mm->nr_ptes);
412 }
413
414 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
415                                 unsigned long addr, unsigned long end,
416                                 unsigned long floor, unsigned long ceiling)
417 {
418         pmd_t *pmd;
419         unsigned long next;
420         unsigned long start;
421
422         start = addr;
423         pmd = pmd_offset(pud, addr);
424         do {
425                 next = pmd_addr_end(addr, end);
426                 if (pmd_none_or_clear_bad(pmd))
427                         continue;
428                 free_pte_range(tlb, pmd, addr);
429         } while (pmd++, addr = next, addr != end);
430
431         start &= PUD_MASK;
432         if (start < floor)
433                 return;
434         if (ceiling) {
435                 ceiling &= PUD_MASK;
436                 if (!ceiling)
437                         return;
438         }
439         if (end - 1 > ceiling - 1)
440                 return;
441
442         pmd = pmd_offset(pud, start);
443         pud_clear(pud);
444         pmd_free_tlb(tlb, pmd, start);
445         mm_dec_nr_pmds(tlb->mm);
446 }
447
448 static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
449                                 unsigned long addr, unsigned long end,
450                                 unsigned long floor, unsigned long ceiling)
451 {
452         pud_t *pud;
453         unsigned long next;
454         unsigned long start;
455
456         start = addr;
457         pud = pud_offset(p4d, addr);
458         do {
459                 next = pud_addr_end(addr, end);
460                 if (pud_none_or_clear_bad(pud))
461                         continue;
462                 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
463         } while (pud++, addr = next, addr != end);
464
465         start &= P4D_MASK;
466         if (start < floor)
467                 return;
468         if (ceiling) {
469                 ceiling &= P4D_MASK;
470                 if (!ceiling)
471                         return;
472         }
473         if (end - 1 > ceiling - 1)
474                 return;
475
476         pud = pud_offset(p4d, start);
477         p4d_clear(p4d);
478         pud_free_tlb(tlb, pud, start);
479 }
480
481 static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
482                                 unsigned long addr, unsigned long end,
483                                 unsigned long floor, unsigned long ceiling)
484 {
485         p4d_t *p4d;
486         unsigned long next;
487         unsigned long start;
488
489         start = addr;
490         p4d = p4d_offset(pgd, addr);
491         do {
492                 next = p4d_addr_end(addr, end);
493                 if (p4d_none_or_clear_bad(p4d))
494                         continue;
495                 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
496         } while (p4d++, addr = next, addr != end);
497
498         start &= PGDIR_MASK;
499         if (start < floor)
500                 return;
501         if (ceiling) {
502                 ceiling &= PGDIR_MASK;
503                 if (!ceiling)
504                         return;
505         }
506         if (end - 1 > ceiling - 1)
507                 return;
508
509         p4d = p4d_offset(pgd, start);
510         pgd_clear(pgd);
511         p4d_free_tlb(tlb, p4d, start);
512 }
513
514 /*
515  * This function frees user-level page tables of a process.
516  */
517 void free_pgd_range(struct mmu_gather *tlb,
518                         unsigned long addr, unsigned long end,
519                         unsigned long floor, unsigned long ceiling)
520 {
521         pgd_t *pgd;
522         unsigned long next;
523
524         /*
525          * The next few lines have given us lots of grief...
526          *
527          * Why are we testing PMD* at this top level?  Because often
528          * there will be no work to do at all, and we'd prefer not to
529          * go all the way down to the bottom just to discover that.
530          *
531          * Why all these "- 1"s?  Because 0 represents both the bottom
532          * of the address space and the top of it (using -1 for the
533          * top wouldn't help much: the masks would do the wrong thing).
534          * The rule is that addr 0 and floor 0 refer to the bottom of
535          * the address space, but end 0 and ceiling 0 refer to the top
536          * Comparisons need to use "end - 1" and "ceiling - 1" (though
537          * that end 0 case should be mythical).
538          *
539          * Wherever addr is brought up or ceiling brought down, we must
540          * be careful to reject "the opposite 0" before it confuses the
541          * subsequent tests.  But what about where end is brought down
542          * by PMD_SIZE below? no, end can't go down to 0 there.
543          *
544          * Whereas we round start (addr) and ceiling down, by different
545          * masks at different levels, in order to test whether a table
546          * now has no other vmas using it, so can be freed, we don't
547          * bother to round floor or end up - the tests don't need that.
548          */
549
550         addr &= PMD_MASK;
551         if (addr < floor) {
552                 addr += PMD_SIZE;
553                 if (!addr)
554                         return;
555         }
556         if (ceiling) {
557                 ceiling &= PMD_MASK;
558                 if (!ceiling)
559                         return;
560         }
561         if (end - 1 > ceiling - 1)
562                 end -= PMD_SIZE;
563         if (addr > end - 1)
564                 return;
565         /*
566          * We add page table cache pages with PAGE_SIZE,
567          * (see pte_free_tlb()), flush the tlb if we need
568          */
569         tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
570         pgd = pgd_offset(tlb->mm, addr);
571         do {
572                 next = pgd_addr_end(addr, end);
573                 if (pgd_none_or_clear_bad(pgd))
574                         continue;
575                 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
576         } while (pgd++, addr = next, addr != end);
577 }
578
579 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
580                 unsigned long floor, unsigned long ceiling)
581 {
582         while (vma) {
583                 struct vm_area_struct *next = vma->vm_next;
584                 unsigned long addr = vma->vm_start;
585
586                 /*
587                  * Hide vma from rmap and truncate_pagecache before freeing
588                  * pgtables
589                  */
590                 unlink_anon_vmas(vma);
591                 unlink_file_vma(vma);
592
593                 if (is_vm_hugetlb_page(vma)) {
594                         hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
595                                 floor, next ? next->vm_start : ceiling);
596                 } else {
597                         /*
598                          * Optimization: gather nearby vmas into one call down
599                          */
600                         while (next && next->vm_start <= vma->vm_end + PMD_SIZE
601                                && !is_vm_hugetlb_page(next)) {
602                                 vma = next;
603                                 next = vma->vm_next;
604                                 unlink_anon_vmas(vma);
605                                 unlink_file_vma(vma);
606                         }
607                         free_pgd_range(tlb, addr, vma->vm_end,
608                                 floor, next ? next->vm_start : ceiling);
609                 }
610                 vma = next;
611         }
612 }
613
614 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
615 {
616         spinlock_t *ptl;
617         pgtable_t new = pte_alloc_one(mm, address);
618         if (!new)
619                 return -ENOMEM;
620
621         /*
622          * Ensure all pte setup (eg. pte page lock and page clearing) are
623          * visible before the pte is made visible to other CPUs by being
624          * put into page tables.
625          *
626          * The other side of the story is the pointer chasing in the page
627          * table walking code (when walking the page table without locking;
628          * ie. most of the time). Fortunately, these data accesses consist
629          * of a chain of data-dependent loads, meaning most CPUs (alpha
630          * being the notable exception) will already guarantee loads are
631          * seen in-order. See the alpha page table accessors for the
632          * smp_read_barrier_depends() barriers in page table walking code.
633          */
634         smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
635
636         ptl = pmd_lock(mm, pmd);
637         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
638                 atomic_long_inc(&mm->nr_ptes);
639                 pmd_populate(mm, pmd, new);
640                 new = NULL;
641         }
642         spin_unlock(ptl);
643         if (new)
644                 pte_free(mm, new);
645         return 0;
646 }
647
648 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
649 {
650         pte_t *new = pte_alloc_one_kernel(&init_mm, address);
651         if (!new)
652                 return -ENOMEM;
653
654         smp_wmb(); /* See comment in __pte_alloc */
655
656         spin_lock(&init_mm.page_table_lock);
657         if (likely(pmd_none(*pmd))) {   /* Has another populated it ? */
658                 pmd_populate_kernel(&init_mm, pmd, new);
659                 new = NULL;
660         }
661         spin_unlock(&init_mm.page_table_lock);
662         if (new)
663                 pte_free_kernel(&init_mm, new);
664         return 0;
665 }
666
667 static inline void init_rss_vec(int *rss)
668 {
669         memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
670 }
671
672 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
673 {
674         int i;
675
676         if (current->mm == mm)
677                 sync_mm_rss(mm);
678         for (i = 0; i < NR_MM_COUNTERS; i++)
679                 if (rss[i])
680                         add_mm_counter(mm, i, rss[i]);
681 }
682
683 /*
684  * This function is called to print an error when a bad pte
685  * is found. For example, we might have a PFN-mapped pte in
686  * a region that doesn't allow it.
687  *
688  * The calling function must still handle the error.
689  */
690 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
691                           pte_t pte, struct page *page)
692 {
693         pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
694         p4d_t *p4d = p4d_offset(pgd, addr);
695         pud_t *pud = pud_offset(p4d, addr);
696         pmd_t *pmd = pmd_offset(pud, addr);
697         struct address_space *mapping;
698         pgoff_t index;
699         static unsigned long resume;
700         static unsigned long nr_shown;
701         static unsigned long nr_unshown;
702
703         /*
704          * Allow a burst of 60 reports, then keep quiet for that minute;
705          * or allow a steady drip of one report per second.
706          */
707         if (nr_shown == 60) {
708                 if (time_before(jiffies, resume)) {
709                         nr_unshown++;
710                         return;
711                 }
712                 if (nr_unshown) {
713                         pr_alert("BUG: Bad page map: %lu messages suppressed\n",
714                                  nr_unshown);
715                         nr_unshown = 0;
716                 }
717                 nr_shown = 0;
718         }
719         if (nr_shown++ == 0)
720                 resume = jiffies + 60 * HZ;
721
722         mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
723         index = linear_page_index(vma, addr);
724
725         pr_alert("BUG: Bad page map in process %s  pte:%08llx pmd:%08llx\n",
726                  current->comm,
727                  (long long)pte_val(pte), (long long)pmd_val(*pmd));
728         if (page)
729                 dump_page(page, "bad pte");
730         pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
731                  (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
732         /*
733          * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
734          */
735         pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
736                  vma->vm_file,
737                  vma->vm_ops ? vma->vm_ops->fault : NULL,
738                  vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
739                  mapping ? mapping->a_ops->readpage : NULL);
740         dump_stack();
741         add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
742 }
743
744 /*
745  * vm_normal_page -- This function gets the "struct page" associated with a pte.
746  *
747  * "Special" mappings do not wish to be associated with a "struct page" (either
748  * it doesn't exist, or it exists but they don't want to touch it). In this
749  * case, NULL is returned here. "Normal" mappings do have a struct page.
750  *
751  * There are 2 broad cases. Firstly, an architecture may define a pte_special()
752  * pte bit, in which case this function is trivial. Secondly, an architecture
753  * may not have a spare pte bit, which requires a more complicated scheme,
754  * described below.
755  *
756  * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
757  * special mapping (even if there are underlying and valid "struct pages").
758  * COWed pages of a VM_PFNMAP are always normal.
759  *
760  * The way we recognize COWed pages within VM_PFNMAP mappings is through the
761  * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
762  * set, and the vm_pgoff will point to the first PFN mapped: thus every special
763  * mapping will always honor the rule
764  *
765  *      pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
766  *
767  * And for normal mappings this is false.
768  *
769  * This restricts such mappings to be a linear translation from virtual address
770  * to pfn. To get around this restriction, we allow arbitrary mappings so long
771  * as the vma is not a COW mapping; in that case, we know that all ptes are
772  * special (because none can have been COWed).
773  *
774  *
775  * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
776  *
777  * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
778  * page" backing, however the difference is that _all_ pages with a struct
779  * page (that is, those where pfn_valid is true) are refcounted and considered
780  * normal pages by the VM. The disadvantage is that pages are refcounted
781  * (which can be slower and simply not an option for some PFNMAP users). The
782  * advantage is that we don't have to follow the strict linearity rule of
783  * PFNMAP mappings in order to support COWable mappings.
784  *
785  */
786 #ifdef __HAVE_ARCH_PTE_SPECIAL
787 # define HAVE_PTE_SPECIAL 1
788 #else
789 # define HAVE_PTE_SPECIAL 0
790 #endif
791 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
792                                 pte_t pte)
793 {
794         unsigned long pfn = pte_pfn(pte);
795
796         if (HAVE_PTE_SPECIAL) {
797                 if (likely(!pte_special(pte)))
798                         goto check_pfn;
799                 if (vma->vm_ops && vma->vm_ops->find_special_page)
800                         return vma->vm_ops->find_special_page(vma, addr);
801                 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
802                         return NULL;
803                 if (!is_zero_pfn(pfn))
804                         print_bad_pte(vma, addr, pte, NULL);
805                 return NULL;
806         }
807
808         /* !HAVE_PTE_SPECIAL case follows: */
809
810         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
811                 if (vma->vm_flags & VM_MIXEDMAP) {
812                         if (!pfn_valid(pfn))
813                                 return NULL;
814                         goto out;
815                 } else {
816                         unsigned long off;
817                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
818                         if (pfn == vma->vm_pgoff + off)
819                                 return NULL;
820                         if (!is_cow_mapping(vma->vm_flags))
821                                 return NULL;
822                 }
823         }
824
825         if (is_zero_pfn(pfn))
826                 return NULL;
827 check_pfn:
828         if (unlikely(pfn > highest_memmap_pfn)) {
829                 print_bad_pte(vma, addr, pte, NULL);
830                 return NULL;
831         }
832
833         /*
834          * NOTE! We still have PageReserved() pages in the page tables.
835          * eg. VDSO mappings can cause them to exist.
836          */
837 out:
838         return pfn_to_page(pfn);
839 }
840
841 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
842 struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
843                                 pmd_t pmd)
844 {
845         unsigned long pfn = pmd_pfn(pmd);
846
847         /*
848          * There is no pmd_special() but there may be special pmds, e.g.
849          * in a direct-access (dax) mapping, so let's just replicate the
850          * !HAVE_PTE_SPECIAL case from vm_normal_page() here.
851          */
852         if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
853                 if (vma->vm_flags & VM_MIXEDMAP) {
854                         if (!pfn_valid(pfn))
855                                 return NULL;
856                         goto out;
857                 } else {
858                         unsigned long off;
859                         off = (addr - vma->vm_start) >> PAGE_SHIFT;
860                         if (pfn == vma->vm_pgoff + off)
861                                 return NULL;
862                         if (!is_cow_mapping(vma->vm_flags))
863                                 return NULL;
864                 }
865         }
866
867         if (is_zero_pfn(pfn))
868                 return NULL;
869         if (unlikely(pfn > highest_memmap_pfn))
870                 return NULL;
871
872         /*
873          * NOTE! We still have PageReserved() pages in the page tables.
874          * eg. VDSO mappings can cause them to exist.
875          */
876 out:
877         return pfn_to_page(pfn);
878 }
879 #endif
880
881 /*
882  * copy one vm_area from one task to the other. Assumes the page tables
883  * already present in the new task to be cleared in the whole range
884  * covered by this vma.
885  */
886
887 static inline unsigned long
888 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
889                 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
890                 unsigned long addr, int *rss)
891 {
892         unsigned long vm_flags = vma->vm_flags;
893         pte_t pte = *src_pte;
894         struct page *page;
895
896         /* pte contains position in swap or file, so copy. */
897         if (unlikely(!pte_present(pte))) {
898                 swp_entry_t entry = pte_to_swp_entry(pte);
899
900                 if (likely(!non_swap_entry(entry))) {
901                         if (swap_duplicate(entry) < 0)
902                                 return entry.val;
903
904                         /* make sure dst_mm is on swapoff's mmlist. */
905                         if (unlikely(list_empty(&dst_mm->mmlist))) {
906                                 spin_lock(&mmlist_lock);
907                                 if (list_empty(&dst_mm->mmlist))
908                                         list_add(&dst_mm->mmlist,
909                                                         &src_mm->mmlist);
910                                 spin_unlock(&mmlist_lock);
911                         }
912                         rss[MM_SWAPENTS]++;
913                 } else if (is_migration_entry(entry)) {
914                         page = migration_entry_to_page(entry);
915
916                         rss[mm_counter(page)]++;
917
918                         if (is_write_migration_entry(entry) &&
919                                         is_cow_mapping(vm_flags)) {
920                                 /*
921                                  * COW mappings require pages in both
922                                  * parent and child to be set to read.
923                                  */
924                                 make_migration_entry_read(&entry);
925                                 pte = swp_entry_to_pte(entry);
926                                 if (pte_swp_soft_dirty(*src_pte))
927                                         pte = pte_swp_mksoft_dirty(pte);
928                                 set_pte_at(src_mm, addr, src_pte, pte);
929                         }
930                 }
931                 goto out_set_pte;
932         }
933
934         /*
935          * If it's a COW mapping, write protect it both
936          * in the parent and the child
937          */
938         if (is_cow_mapping(vm_flags)) {
939                 ptep_set_wrprotect(src_mm, addr, src_pte);
940                 pte = pte_wrprotect(pte);
941         }
942
943         /*
944          * If it's a shared mapping, mark it clean in
945          * the child
946          */
947         if (vm_flags & VM_SHARED)
948                 pte = pte_mkclean(pte);
949         pte = pte_mkold(pte);
950
951         page = vm_normal_page(vma, addr, pte);
952         if (page) {
953                 get_page(page);
954                 page_dup_rmap(page, false);
955                 rss[mm_counter(page)]++;
956         }
957
958 out_set_pte:
959         set_pte_at(dst_mm, addr, dst_pte, pte);
960         return 0;
961 }
962
963 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
964                    pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
965                    unsigned long addr, unsigned long end)
966 {
967         pte_t *orig_src_pte, *orig_dst_pte;
968         pte_t *src_pte, *dst_pte;
969         spinlock_t *src_ptl, *dst_ptl;
970         int progress = 0;
971         int rss[NR_MM_COUNTERS];
972         swp_entry_t entry = (swp_entry_t){0};
973
974 again:
975         init_rss_vec(rss);
976
977         dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
978         if (!dst_pte)
979                 return -ENOMEM;
980         src_pte = pte_offset_map(src_pmd, addr);
981         src_ptl = pte_lockptr(src_mm, src_pmd);
982         spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
983         orig_src_pte = src_pte;
984         orig_dst_pte = dst_pte;
985         arch_enter_lazy_mmu_mode();
986
987         do {
988                 /*
989                  * We are holding two locks at this point - either of them
990                  * could generate latencies in another task on another CPU.
991                  */
992                 if (progress >= 32) {
993                         progress = 0;
994                         if (need_resched() ||
995                             spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
996                                 break;
997                 }
998                 if (pte_none(*src_pte)) {
999                         progress++;
1000                         continue;
1001                 }
1002                 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
1003                                                         vma, addr, rss);
1004                 if (entry.val)
1005                         break;
1006                 progress += 8;
1007         } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
1008
1009         arch_leave_lazy_mmu_mode();
1010         spin_unlock(src_ptl);
1011         pte_unmap(orig_src_pte);
1012         add_mm_rss_vec(dst_mm, rss);
1013         pte_unmap_unlock(orig_dst_pte, dst_ptl);
1014         cond_resched();
1015
1016         if (entry.val) {
1017                 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
1018                         return -ENOMEM;
1019                 progress = 0;
1020         }
1021         if (addr != end)
1022                 goto again;
1023         return 0;
1024 }
1025
1026 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1027                 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
1028                 unsigned long addr, unsigned long end)
1029 {
1030         pmd_t *src_pmd, *dst_pmd;
1031         unsigned long next;
1032
1033         dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1034         if (!dst_pmd)
1035                 return -ENOMEM;
1036         src_pmd = pmd_offset(src_pud, addr);
1037         do {
1038                 next = pmd_addr_end(addr, end);
1039                 if (pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) {
1040                         int err;
1041                         VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
1042                         err = copy_huge_pmd(dst_mm, src_mm,
1043                                             dst_pmd, src_pmd, addr, vma);
1044                         if (err == -ENOMEM)
1045                                 return -ENOMEM;
1046                         if (!err)
1047                                 continue;
1048                         /* fall through */
1049                 }
1050                 if (pmd_none_or_clear_bad(src_pmd))
1051                         continue;
1052                 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1053                                                 vma, addr, next))
1054                         return -ENOMEM;
1055         } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1056         return 0;
1057 }
1058
1059 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1060                 p4d_t *dst_p4d, p4d_t *src_p4d, struct vm_area_struct *vma,
1061                 unsigned long addr, unsigned long end)
1062 {
1063         pud_t *src_pud, *dst_pud;
1064         unsigned long next;
1065
1066         dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1067         if (!dst_pud)
1068                 return -ENOMEM;
1069         src_pud = pud_offset(src_p4d, addr);
1070         do {
1071                 next = pud_addr_end(addr, end);
1072                 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1073                         int err;
1074
1075                         VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma);
1076                         err = copy_huge_pud(dst_mm, src_mm,
1077                                             dst_pud, src_pud, addr, vma);
1078                         if (err == -ENOMEM)
1079                                 return -ENOMEM;
1080                         if (!err)
1081                                 continue;
1082                         /* fall through */
1083                 }
1084                 if (pud_none_or_clear_bad(src_pud))
1085                         continue;
1086                 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1087                                                 vma, addr, next))
1088                         return -ENOMEM;
1089         } while (dst_pud++, src_pud++, addr = next, addr != end);
1090         return 0;
1091 }
1092
1093 static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1094                 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1095                 unsigned long addr, unsigned long end)
1096 {
1097         p4d_t *src_p4d, *dst_p4d;
1098         unsigned long next;
1099
1100         dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1101         if (!dst_p4d)
1102                 return -ENOMEM;
1103         src_p4d = p4d_offset(src_pgd, addr);
1104         do {
1105                 next = p4d_addr_end(addr, end);
1106                 if (p4d_none_or_clear_bad(src_p4d))
1107                         continue;
1108                 if (copy_pud_range(dst_mm, src_mm, dst_p4d, src_p4d,
1109                                                 vma, addr, next))
1110                         return -ENOMEM;
1111         } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1112         return 0;
1113 }
1114
1115 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1116                 struct vm_area_struct *vma)
1117 {
1118         pgd_t *src_pgd, *dst_pgd;
1119         unsigned long next;
1120         unsigned long addr = vma->vm_start;
1121         unsigned long end = vma->vm_end;
1122         unsigned long mmun_start;       /* For mmu_notifiers */
1123         unsigned long mmun_end;         /* For mmu_notifiers */
1124         bool is_cow;
1125         int ret;
1126
1127         /*
1128          * Don't copy ptes where a page fault will fill them correctly.
1129          * Fork becomes much lighter when there are big shared or private
1130          * readonly mappings. The tradeoff is that copy_page_range is more
1131          * efficient than faulting.
1132          */
1133         if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
1134                         !vma->anon_vma)
1135                 return 0;
1136
1137         if (is_vm_hugetlb_page(vma))
1138                 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1139
1140         if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1141                 /*
1142                  * We do not free on error cases below as remove_vma
1143                  * gets called on error from higher level routine
1144                  */
1145                 ret = track_pfn_copy(vma);
1146                 if (ret)
1147                         return ret;
1148         }
1149
1150         /*
1151          * We need to invalidate the secondary MMU mappings only when
1152          * there could be a permission downgrade on the ptes of the
1153          * parent mm. And a permission downgrade will only happen if
1154          * is_cow_mapping() returns true.
1155          */
1156         is_cow = is_cow_mapping(vma->vm_flags);
1157         mmun_start = addr;
1158         mmun_end   = end;
1159         if (is_cow)
1160                 mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1161                                                     mmun_end);
1162
1163         ret = 0;
1164         dst_pgd = pgd_offset(dst_mm, addr);
1165         src_pgd = pgd_offset(src_mm, addr);
1166         do {
1167                 next = pgd_addr_end(addr, end);
1168                 if (pgd_none_or_clear_bad(src_pgd))
1169                         continue;
1170                 if (unlikely(copy_p4d_range(dst_mm, src_mm, dst_pgd, src_pgd,
1171                                             vma, addr, next))) {
1172                         ret = -ENOMEM;
1173                         break;
1174                 }
1175         } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1176
1177         if (is_cow)
1178                 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1179         return ret;
1180 }
1181
1182 static unsigned long zap_pte_range(struct mmu_gather *tlb,
1183                                 struct vm_area_struct *vma, pmd_t *pmd,
1184                                 unsigned long addr, unsigned long end,
1185                                 struct zap_details *details)
1186 {
1187         struct mm_struct *mm = tlb->mm;
1188         int force_flush = 0;
1189         int rss[NR_MM_COUNTERS];
1190         spinlock_t *ptl;
1191         pte_t *start_pte;
1192         pte_t *pte;
1193         swp_entry_t entry;
1194
1195         tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
1196 again:
1197         init_rss_vec(rss);
1198         start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1199         pte = start_pte;
1200         flush_tlb_batched_pending(mm);
1201         arch_enter_lazy_mmu_mode();
1202         do {
1203                 pte_t ptent = *pte;
1204                 if (pte_none(ptent))
1205                         continue;
1206
1207                 if (pte_present(ptent)) {
1208                         struct page *page;
1209
1210                         page = vm_normal_page(vma, addr, ptent);
1211                         if (unlikely(details) && page) {
1212                                 /*
1213                                  * unmap_shared_mapping_pages() wants to
1214                                  * invalidate cache without truncating:
1215                                  * unmap shared but keep private pages.
1216                                  */
1217                                 if (details->check_mapping &&
1218                                     details->check_mapping != page_rmapping(page))
1219                                         continue;
1220                         }
1221                         ptent = ptep_get_and_clear_full(mm, addr, pte,
1222                                                         tlb->fullmm);
1223                         tlb_remove_tlb_entry(tlb, pte, addr);
1224                         if (unlikely(!page))
1225                                 continue;
1226
1227                         if (!PageAnon(page)) {
1228                                 if (pte_dirty(ptent)) {
1229                                         force_flush = 1;
1230                                         set_page_dirty(page);
1231                                 }
1232                                 if (pte_young(ptent) &&
1233                                     likely(!(vma->vm_flags & VM_SEQ_READ)))
1234                                         mark_page_accessed(page);
1235                         }
1236                         rss[mm_counter(page)]--;
1237                         page_remove_rmap(page, false);
1238                         if (unlikely(page_mapcount(page) < 0))
1239                                 print_bad_pte(vma, addr, ptent, page);
1240                         if (unlikely(__tlb_remove_page(tlb, page))) {
1241                                 force_flush = 1;
1242                                 addr += PAGE_SIZE;
1243                                 break;
1244                         }
1245                         continue;
1246                 }
1247                 /* If details->check_mapping, we leave swap entries. */
1248                 if (unlikely(details))
1249                         continue;
1250
1251                 entry = pte_to_swp_entry(ptent);
1252                 if (!non_swap_entry(entry))
1253                         rss[MM_SWAPENTS]--;
1254                 else if (is_migration_entry(entry)) {
1255                         struct page *page;
1256
1257                         page = migration_entry_to_page(entry);
1258                         rss[mm_counter(page)]--;
1259                 }
1260                 if (unlikely(!free_swap_and_cache(entry)))
1261                         print_bad_pte(vma, addr, ptent, NULL);
1262                 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1263         } while (pte++, addr += PAGE_SIZE, addr != end);
1264
1265         add_mm_rss_vec(mm, rss);
1266         arch_leave_lazy_mmu_mode();
1267
1268         /* Do the actual TLB flush before dropping ptl */
1269         if (force_flush)
1270                 tlb_flush_mmu_tlbonly(tlb);
1271         pte_unmap_unlock(start_pte, ptl);
1272
1273         /*
1274          * If we forced a TLB flush (either due to running out of
1275          * batch buffers or because we needed to flush dirty TLB
1276          * entries before releasing the ptl), free the batched
1277          * memory too. Restart if we didn't do everything.
1278          */
1279         if (force_flush) {
1280                 force_flush = 0;
1281                 tlb_flush_mmu_free(tlb);
1282                 if (addr != end)
1283                         goto again;
1284         }
1285
1286         return addr;
1287 }
1288
1289 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1290                                 struct vm_area_struct *vma, pud_t *pud,
1291                                 unsigned long addr, unsigned long end,
1292                                 struct zap_details *details)
1293 {
1294         pmd_t *pmd;
1295         unsigned long next;
1296
1297         pmd = pmd_offset(pud, addr);
1298         do {
1299                 next = pmd_addr_end(addr, end);
1300                 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1301                         if (next - addr != HPAGE_PMD_SIZE) {
1302                                 VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
1303                                     !rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1304                                 __split_huge_pmd(vma, pmd, addr, false, NULL);
1305                         } else if (zap_huge_pmd(tlb, vma, pmd, addr))
1306                                 goto next;
1307                         /* fall through */
1308                 }
1309                 /*
1310                  * Here there can be other concurrent MADV_DONTNEED or
1311                  * trans huge page faults running, and if the pmd is
1312                  * none or trans huge it can change under us. This is
1313                  * because MADV_DONTNEED holds the mmap_sem in read
1314                  * mode.
1315                  */
1316                 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1317                         goto next;
1318                 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1319 next:
1320                 cond_resched();
1321         } while (pmd++, addr = next, addr != end);
1322
1323         return addr;
1324 }
1325
1326 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1327                                 struct vm_area_struct *vma, p4d_t *p4d,
1328                                 unsigned long addr, unsigned long end,
1329                                 struct zap_details *details)
1330 {
1331         pud_t *pud;
1332         unsigned long next;
1333
1334         pud = pud_offset(p4d, addr);
1335         do {
1336                 next = pud_addr_end(addr, end);
1337                 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1338                         if (next - addr != HPAGE_PUD_SIZE) {
1339                                 VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1340                                 split_huge_pud(vma, pud, addr);
1341                         } else if (zap_huge_pud(tlb, vma, pud, addr))
1342                                 goto next;
1343                         /* fall through */
1344                 }
1345                 if (pud_none_or_clear_bad(pud))
1346                         continue;
1347                 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1348 next:
1349                 cond_resched();
1350         } while (pud++, addr = next, addr != end);
1351
1352         return addr;
1353 }
1354
1355 static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1356                                 struct vm_area_struct *vma, pgd_t *pgd,
1357                                 unsigned long addr, unsigned long end,
1358                                 struct zap_details *details)
1359 {
1360         p4d_t *p4d;
1361         unsigned long next;
1362
1363         p4d = p4d_offset(pgd, addr);
1364         do {
1365                 next = p4d_addr_end(addr, end);
1366                 if (p4d_none_or_clear_bad(p4d))
1367                         continue;
1368                 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1369         } while (p4d++, addr = next, addr != end);
1370
1371         return addr;
1372 }
1373
1374 void unmap_page_range(struct mmu_gather *tlb,
1375                              struct vm_area_struct *vma,
1376                              unsigned long addr, unsigned long end,
1377                              struct zap_details *details)
1378 {
1379         pgd_t *pgd;
1380         unsigned long next;
1381
1382         BUG_ON(addr >= end);
1383         tlb_start_vma(tlb, vma);
1384         pgd = pgd_offset(vma->vm_mm, addr);
1385         do {
1386                 next = pgd_addr_end(addr, end);
1387                 if (pgd_none_or_clear_bad(pgd))
1388                         continue;
1389                 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1390         } while (pgd++, addr = next, addr != end);
1391         tlb_end_vma(tlb, vma);
1392 }
1393
1394
1395 static void unmap_single_vma(struct mmu_gather *tlb,
1396                 struct vm_area_struct *vma, unsigned long start_addr,
1397                 unsigned long end_addr,
1398                 struct zap_details *details)
1399 {
1400         unsigned long start = max(vma->vm_start, start_addr);
1401         unsigned long end;
1402
1403         if (start >= vma->vm_end)
1404                 return;
1405         end = min(vma->vm_end, end_addr);
1406         if (end <= vma->vm_start)
1407                 return;
1408
1409         if (vma->vm_file)
1410                 uprobe_munmap(vma, start, end);
1411
1412         if (unlikely(vma->vm_flags & VM_PFNMAP))
1413                 untrack_pfn(vma, 0, 0);
1414
1415         if (start != end) {
1416                 if (unlikely(is_vm_hugetlb_page(vma))) {
1417                         /*
1418                          * It is undesirable to test vma->vm_file as it
1419                          * should be non-null for valid hugetlb area.
1420                          * However, vm_file will be NULL in the error
1421                          * cleanup path of mmap_region. When
1422                          * hugetlbfs ->mmap method fails,
1423                          * mmap_region() nullifies vma->vm_file
1424                          * before calling this function to clean up.
1425                          * Since no pte has actually been setup, it is
1426                          * safe to do nothing in this case.
1427                          */
1428                         if (vma->vm_file) {
1429                                 i_mmap_lock_write(vma->vm_file->f_mapping);
1430                                 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1431                                 i_mmap_unlock_write(vma->vm_file->f_mapping);
1432                         }
1433                 } else
1434                         unmap_page_range(tlb, vma, start, end, details);
1435         }
1436 }
1437
1438 /**
1439  * unmap_vmas - unmap a range of memory covered by a list of vma's
1440  * @tlb: address of the caller's struct mmu_gather
1441  * @vma: the starting vma
1442  * @start_addr: virtual address at which to start unmapping
1443  * @end_addr: virtual address at which to end unmapping
1444  *
1445  * Unmap all pages in the vma list.
1446  *
1447  * Only addresses between `start' and `end' will be unmapped.
1448  *
1449  * The VMA list must be sorted in ascending virtual address order.
1450  *
1451  * unmap_vmas() assumes that the caller will flush the whole unmapped address
1452  * range after unmap_vmas() returns.  So the only responsibility here is to
1453  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1454  * drops the lock and schedules.
1455  */
1456 void unmap_vmas(struct mmu_gather *tlb,
1457                 struct vm_area_struct *vma, unsigned long start_addr,
1458                 unsigned long end_addr)
1459 {
1460         struct mm_struct *mm = vma->vm_mm;
1461
1462         mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1463         for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1464                 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1465         mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1466 }
1467
1468 /**
1469  * zap_page_range - remove user pages in a given range
1470  * @vma: vm_area_struct holding the applicable pages
1471  * @start: starting address of pages to zap
1472  * @size: number of bytes to zap
1473  *
1474  * Caller must protect the VMA list
1475  */
1476 void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1477                 unsigned long size)
1478 {
1479         struct mm_struct *mm = vma->vm_mm;
1480         struct mmu_gather tlb;
1481         unsigned long end = start + size;
1482
1483         lru_add_drain();
1484         tlb_gather_mmu(&tlb, mm, start, end);
1485         update_hiwater_rss(mm);
1486         mmu_notifier_invalidate_range_start(mm, start, end);
1487         for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1488                 unmap_single_vma(&tlb, vma, start, end, NULL);
1489         mmu_notifier_invalidate_range_end(mm, start, end);
1490         tlb_finish_mmu(&tlb, start, end);
1491 }
1492
1493 /**
1494  * zap_page_range_single - remove user pages in a given range
1495  * @vma: vm_area_struct holding the applicable pages
1496  * @address: starting address of pages to zap
1497  * @size: number of bytes to zap
1498  * @details: details of shared cache invalidation
1499  *
1500  * The range must fit into one VMA.
1501  */
1502 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1503                 unsigned long size, struct zap_details *details)
1504 {
1505         struct mm_struct *mm = vma->vm_mm;
1506         struct mmu_gather tlb;
1507         unsigned long end = address + size;
1508
1509         lru_add_drain();
1510         tlb_gather_mmu(&tlb, mm, address, end);
1511         update_hiwater_rss(mm);
1512         mmu_notifier_invalidate_range_start(mm, address, end);
1513         unmap_single_vma(&tlb, vma, address, end, details);
1514         mmu_notifier_invalidate_range_end(mm, address, end);
1515         tlb_finish_mmu(&tlb, address, end);
1516 }
1517
1518 /**
1519  * zap_vma_ptes - remove ptes mapping the vma
1520  * @vma: vm_area_struct holding ptes to be zapped
1521  * @address: starting address of pages to zap
1522  * @size: number of bytes to zap
1523  *
1524  * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1525  *
1526  * The entire address range must be fully contained within the vma.
1527  *
1528  * Returns 0 if successful.
1529  */
1530 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1531                 unsigned long size)
1532 {
1533         if (address < vma->vm_start || address + size > vma->vm_end ||
1534                         !(vma->vm_flags & VM_PFNMAP))
1535                 return -1;
1536         zap_page_range_single(vma, address, size, NULL);
1537         return 0;
1538 }
1539 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1540
1541 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1542                         spinlock_t **ptl)
1543 {
1544         pgd_t *pgd;
1545         p4d_t *p4d;
1546         pud_t *pud;
1547         pmd_t *pmd;
1548
1549         pgd = pgd_offset(mm, addr);
1550         p4d = p4d_alloc(mm, pgd, addr);
1551         if (!p4d)
1552                 return NULL;
1553         pud = pud_alloc(mm, p4d, addr);
1554         if (!pud)
1555                 return NULL;
1556         pmd = pmd_alloc(mm, pud, addr);
1557         if (!pmd)
1558                 return NULL;
1559
1560         VM_BUG_ON(pmd_trans_huge(*pmd));
1561         return pte_alloc_map_lock(mm, pmd, addr, ptl);
1562 }
1563
1564 /*
1565  * This is the old fallback for page remapping.
1566  *
1567  * For historical reasons, it only allows reserved pages. Only
1568  * old drivers should use this, and they needed to mark their
1569  * pages reserved for the old functions anyway.
1570  */
1571 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1572                         struct page *page, pgprot_t prot)
1573 {
1574         struct mm_struct *mm = vma->vm_mm;
1575         int retval;
1576         pte_t *pte;
1577         spinlock_t *ptl;
1578
1579         retval = -EINVAL;
1580         if (PageAnon(page))
1581                 goto out;
1582         retval = -ENOMEM;
1583         flush_dcache_page(page);
1584         pte = get_locked_pte(mm, addr, &ptl);
1585         if (!pte)
1586                 goto out;
1587         retval = -EBUSY;
1588         if (!pte_none(*pte))
1589                 goto out_unlock;
1590
1591         /* Ok, finally just insert the thing.. */
1592         get_page(page);
1593         inc_mm_counter_fast(mm, mm_counter_file(page));
1594         page_add_file_rmap(page, false);
1595         set_pte_at(mm, addr, pte, mk_pte(page, prot));
1596
1597         retval = 0;
1598         pte_unmap_unlock(pte, ptl);
1599         return retval;
1600 out_unlock:
1601         pte_unmap_unlock(pte, ptl);
1602 out:
1603         return retval;
1604 }
1605
1606 /**
1607  * vm_insert_page - insert single page into user vma
1608  * @vma: user vma to map to
1609  * @addr: target user address of this page
1610  * @page: source kernel page
1611  *
1612  * This allows drivers to insert individual pages they've allocated
1613  * into a user vma.
1614  *
1615  * The page has to be a nice clean _individual_ kernel allocation.
1616  * If you allocate a compound page, you need to have marked it as
1617  * such (__GFP_COMP), or manually just split the page up yourself
1618  * (see split_page()).
1619  *
1620  * NOTE! Traditionally this was done with "remap_pfn_range()" which
1621  * took an arbitrary page protection parameter. This doesn't allow
1622  * that. Your vma protection will have to be set up correctly, which
1623  * means that if you want a shared writable mapping, you'd better
1624  * ask for a shared writable mapping!
1625  *
1626  * The page does not need to be reserved.
1627  *
1628  * Usually this function is called from f_op->mmap() handler
1629  * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1630  * Caller must set VM_MIXEDMAP on vma if it wants to call this
1631  * function from other places, for example from page-fault handler.
1632  */
1633 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1634                         struct page *page)
1635 {
1636         if (addr < vma->vm_start || addr >= vma->vm_end)
1637                 return -EFAULT;
1638         if (!page_count(page))
1639                 return -EINVAL;
1640         if (!(vma->vm_flags & VM_MIXEDMAP)) {
1641                 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1642                 BUG_ON(vma->vm_flags & VM_PFNMAP);
1643                 vma->vm_flags |= VM_MIXEDMAP;
1644         }
1645         return insert_page(vma, addr, page, vma->vm_page_prot);
1646 }
1647 EXPORT_SYMBOL(vm_insert_page);
1648
1649 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1650                         pfn_t pfn, pgprot_t prot)
1651 {
1652         struct mm_struct *mm = vma->vm_mm;
1653         int retval;
1654         pte_t *pte, entry;
1655         spinlock_t *ptl;
1656
1657         retval = -ENOMEM;
1658         pte = get_locked_pte(mm, addr, &ptl);
1659         if (!pte)
1660                 goto out;
1661         retval = -EBUSY;
1662         if (!pte_none(*pte))
1663                 goto out_unlock;
1664
1665         /* Ok, finally just insert the thing.. */
1666         if (pfn_t_devmap(pfn))
1667                 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
1668         else
1669                 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
1670         set_pte_at(mm, addr, pte, entry);
1671         update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1672
1673         retval = 0;
1674 out_unlock:
1675         pte_unmap_unlock(pte, ptl);
1676 out:
1677         return retval;
1678 }
1679
1680 /**
1681  * vm_insert_pfn - insert single pfn into user vma
1682  * @vma: user vma to map to
1683  * @addr: target user address of this page
1684  * @pfn: source kernel pfn
1685  *
1686  * Similar to vm_insert_page, this allows drivers to insert individual pages
1687  * they've allocated into a user vma. Same comments apply.
1688  *
1689  * This function should only be called from a vm_ops->fault handler, and
1690  * in that case the handler should return NULL.
1691  *
1692  * vma cannot be a COW mapping.
1693  *
1694  * As this is called only for pages that do not currently exist, we
1695  * do not need to flush old virtual caches or the TLB.
1696  */
1697 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1698                         unsigned long pfn)
1699 {
1700         return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
1701 }
1702 EXPORT_SYMBOL(vm_insert_pfn);
1703
1704 /**
1705  * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1706  * @vma: user vma to map to
1707  * @addr: target user address of this page
1708  * @pfn: source kernel pfn
1709  * @pgprot: pgprot flags for the inserted page
1710  *
1711  * This is exactly like vm_insert_pfn, except that it allows drivers to
1712  * to override pgprot on a per-page basis.
1713  *
1714  * This only makes sense for IO mappings, and it makes no sense for
1715  * cow mappings.  In general, using multiple vmas is preferable;
1716  * vm_insert_pfn_prot should only be used if using multiple VMAs is
1717  * impractical.
1718  */
1719 int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
1720                         unsigned long pfn, pgprot_t pgprot)
1721 {
1722         int ret;
1723         /*
1724          * Technically, architectures with pte_special can avoid all these
1725          * restrictions (same for remap_pfn_range).  However we would like
1726          * consistency in testing and feature parity among all, so we should
1727          * try to keep these invariants in place for everybody.
1728          */
1729         BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1730         BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1731                                                 (VM_PFNMAP|VM_MIXEDMAP));
1732         BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1733         BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1734
1735         if (addr < vma->vm_start || addr >= vma->vm_end)
1736                 return -EFAULT;
1737
1738         track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
1739
1740         ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot);
1741
1742         return ret;
1743 }
1744 EXPORT_SYMBOL(vm_insert_pfn_prot);
1745
1746 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1747                         pfn_t pfn)
1748 {
1749         pgprot_t pgprot = vma->vm_page_prot;
1750
1751         BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1752
1753         if (addr < vma->vm_start || addr >= vma->vm_end)
1754                 return -EFAULT;
1755
1756         track_pfn_insert(vma, &pgprot, pfn);
1757
1758         /*
1759          * If we don't have pte special, then we have to use the pfn_valid()
1760          * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1761          * refcount the page if pfn_valid is true (hence insert_page rather
1762          * than insert_pfn).  If a zero_pfn were inserted into a VM_MIXEDMAP
1763          * without pte special, it would there be refcounted as a normal page.
1764          */
1765         if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
1766                 struct page *page;
1767
1768                 /*
1769                  * At this point we are committed to insert_page()
1770                  * regardless of whether the caller specified flags that
1771                  * result in pfn_t_has_page() == false.
1772                  */
1773                 page = pfn_to_page(pfn_t_to_pfn(pfn));
1774                 return insert_page(vma, addr, page, pgprot);
1775         }
1776         return insert_pfn(vma, addr, pfn, pgprot);
1777 }
1778 EXPORT_SYMBOL(vm_insert_mixed);
1779
1780 /*
1781  * maps a range of physical memory into the requested pages. the old
1782  * mappings are removed. any references to nonexistent pages results
1783  * in null mappings (currently treated as "copy-on-access")
1784  */
1785 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1786                         unsigned long addr, unsigned long end,
1787                         unsigned long pfn, pgprot_t prot)
1788 {
1789         pte_t *pte;
1790         spinlock_t *ptl;
1791
1792         pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1793         if (!pte)
1794                 return -ENOMEM;
1795         arch_enter_lazy_mmu_mode();
1796         do {
1797                 BUG_ON(!pte_none(*pte));
1798                 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1799                 pfn++;
1800         } while (pte++, addr += PAGE_SIZE, addr != end);
1801         arch_leave_lazy_mmu_mode();
1802         pte_unmap_unlock(pte - 1, ptl);
1803         return 0;
1804 }
1805
1806 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1807                         unsigned long addr, unsigned long end,
1808                         unsigned long pfn, pgprot_t prot)
1809 {
1810         pmd_t *pmd;
1811         unsigned long next;
1812
1813         pfn -= addr >> PAGE_SHIFT;
1814         pmd = pmd_alloc(mm, pud, addr);
1815         if (!pmd)
1816                 return -ENOMEM;
1817         VM_BUG_ON(pmd_trans_huge(*pmd));
1818         do {
1819                 next = pmd_addr_end(addr, end);
1820                 if (remap_pte_range(mm, pmd, addr, next,
1821                                 pfn + (addr >> PAGE_SHIFT), prot))
1822                         return -ENOMEM;
1823         } while (pmd++, addr = next, addr != end);
1824         return 0;
1825 }
1826
1827 static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
1828                         unsigned long addr, unsigned long end,
1829                         unsigned long pfn, pgprot_t prot)
1830 {
1831         pud_t *pud;
1832         unsigned long next;
1833
1834         pfn -= addr >> PAGE_SHIFT;
1835         pud = pud_alloc(mm, p4d, addr);
1836         if (!pud)
1837                 return -ENOMEM;
1838         do {
1839                 next = pud_addr_end(addr, end);
1840                 if (remap_pmd_range(mm, pud, addr, next,
1841                                 pfn + (addr >> PAGE_SHIFT), prot))
1842                         return -ENOMEM;
1843         } while (pud++, addr = next, addr != end);
1844         return 0;
1845 }
1846
1847 static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
1848                         unsigned long addr, unsigned long end,
1849                         unsigned long pfn, pgprot_t prot)
1850 {
1851         p4d_t *p4d;
1852         unsigned long next;
1853
1854         pfn -= addr >> PAGE_SHIFT;
1855         p4d = p4d_alloc(mm, pgd, addr);
1856         if (!p4d)
1857                 return -ENOMEM;
1858         do {
1859                 next = p4d_addr_end(addr, end);
1860                 if (remap_pud_range(mm, p4d, addr, next,
1861                                 pfn + (addr >> PAGE_SHIFT), prot))
1862                         return -ENOMEM;
1863         } while (p4d++, addr = next, addr != end);
1864         return 0;
1865 }
1866
1867 /**
1868  * remap_pfn_range - remap kernel memory to userspace
1869  * @vma: user vma to map to
1870  * @addr: target user address to start at
1871  * @pfn: physical address of kernel memory
1872  * @size: size of map area
1873  * @prot: page protection flags for this mapping
1874  *
1875  *  Note: this is only safe if the mm semaphore is held when called.
1876  */
1877 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1878                     unsigned long pfn, unsigned long size, pgprot_t prot)
1879 {
1880         pgd_t *pgd;
1881         unsigned long next;
1882         unsigned long end = addr + PAGE_ALIGN(size);
1883         struct mm_struct *mm = vma->vm_mm;
1884         unsigned long remap_pfn = pfn;
1885         int err;
1886
1887         /*
1888          * Physically remapped pages are special. Tell the
1889          * rest of the world about it:
1890          *   VM_IO tells people not to look at these pages
1891          *      (accesses can have side effects).
1892          *   VM_PFNMAP tells the core MM that the base pages are just
1893          *      raw PFN mappings, and do not have a "struct page" associated
1894          *      with them.
1895          *   VM_DONTEXPAND
1896          *      Disable vma merging and expanding with mremap().
1897          *   VM_DONTDUMP
1898          *      Omit vma from core dump, even when VM_IO turned off.
1899          *
1900          * There's a horrible special case to handle copy-on-write
1901          * behaviour that some programs depend on. We mark the "original"
1902          * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1903          * See vm_normal_page() for details.
1904          */
1905         if (is_cow_mapping(vma->vm_flags)) {
1906                 if (addr != vma->vm_start || end != vma->vm_end)
1907                         return -EINVAL;
1908                 vma->vm_pgoff = pfn;
1909         }
1910
1911         err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
1912         if (err)
1913                 return -EINVAL;
1914
1915         vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1916
1917         BUG_ON(addr >= end);
1918         pfn -= addr >> PAGE_SHIFT;
1919         pgd = pgd_offset(mm, addr);
1920         flush_cache_range(vma, addr, end);
1921         do {
1922                 next = pgd_addr_end(addr, end);
1923                 err = remap_p4d_range(mm, pgd, addr, next,
1924                                 pfn + (addr >> PAGE_SHIFT), prot);
1925                 if (err)
1926                         break;
1927         } while (pgd++, addr = next, addr != end);
1928
1929         if (err)
1930                 untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
1931
1932         return err;
1933 }
1934 EXPORT_SYMBOL(remap_pfn_range);
1935
1936 /**
1937  * vm_iomap_memory - remap memory to userspace
1938  * @vma: user vma to map to
1939  * @start: start of area
1940  * @len: size of area
1941  *
1942  * This is a simplified io_remap_pfn_range() for common driver use. The
1943  * driver just needs to give us the physical memory range to be mapped,
1944  * we'll figure out the rest from the vma information.
1945  *
1946  * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
1947  * whatever write-combining details or similar.
1948  */
1949 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1950 {
1951         unsigned long vm_len, pfn, pages;
1952
1953         /* Check that the physical memory area passed in looks valid */
1954         if (start + len < start)
1955                 return -EINVAL;
1956         /*
1957          * You *really* shouldn't map things that aren't page-aligned,
1958          * but we've historically allowed it because IO memory might
1959          * just have smaller alignment.
1960          */
1961         len += start & ~PAGE_MASK;
1962         pfn = start >> PAGE_SHIFT;
1963         pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
1964         if (pfn + pages < pfn)
1965                 return -EINVAL;
1966
1967         /* We start the mapping 'vm_pgoff' pages into the area */
1968         if (vma->vm_pgoff > pages)
1969                 return -EINVAL;
1970         pfn += vma->vm_pgoff;
1971         pages -= vma->vm_pgoff;
1972
1973         /* Can we fit all of the mapping? */
1974         vm_len = vma->vm_end - vma->vm_start;
1975         if (vm_len >> PAGE_SHIFT > pages)
1976                 return -EINVAL;
1977
1978         /* Ok, let it rip */
1979         return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
1980 }
1981 EXPORT_SYMBOL(vm_iomap_memory);
1982
1983 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
1984                                      unsigned long addr, unsigned long end,
1985                                      pte_fn_t fn, void *data)
1986 {
1987         pte_t *pte;
1988         int err;
1989         pgtable_t token;
1990         spinlock_t *uninitialized_var(ptl);
1991
1992         pte = (mm == &init_mm) ?
1993                 pte_alloc_kernel(pmd, addr) :
1994                 pte_alloc_map_lock(mm, pmd, addr, &ptl);
1995         if (!pte)
1996                 return -ENOMEM;
1997
1998         BUG_ON(pmd_huge(*pmd));
1999
2000         arch_enter_lazy_mmu_mode();
2001
2002         token = pmd_pgtable(*pmd);
2003
2004         do {
2005                 err = fn(pte++, token, addr, data);
2006                 if (err)
2007                         break;
2008         } while (addr += PAGE_SIZE, addr != end);
2009
2010         arch_leave_lazy_mmu_mode();
2011
2012         if (mm != &init_mm)
2013                 pte_unmap_unlock(pte-1, ptl);
2014         return err;
2015 }
2016
2017 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2018                                      unsigned long addr, unsigned long end,
2019                                      pte_fn_t fn, void *data)
2020 {
2021         pmd_t *pmd;
2022         unsigned long next;
2023         int err;
2024
2025         BUG_ON(pud_huge(*pud));
2026
2027         pmd = pmd_alloc(mm, pud, addr);
2028         if (!pmd)
2029                 return -ENOMEM;
2030         do {
2031                 next = pmd_addr_end(addr, end);
2032                 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2033                 if (err)
2034                         break;
2035         } while (pmd++, addr = next, addr != end);
2036         return err;
2037 }
2038
2039 static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2040                                      unsigned long addr, unsigned long end,
2041                                      pte_fn_t fn, void *data)
2042 {
2043         pud_t *pud;
2044         unsigned long next;
2045         int err;
2046
2047         pud = pud_alloc(mm, p4d, addr);
2048         if (!pud)
2049                 return -ENOMEM;
2050         do {
2051                 next = pud_addr_end(addr, end);
2052                 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2053                 if (err)
2054                         break;
2055         } while (pud++, addr = next, addr != end);
2056         return err;
2057 }
2058
2059 static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2060                                      unsigned long addr, unsigned long end,
2061                                      pte_fn_t fn, void *data)
2062 {
2063         p4d_t *p4d;
2064         unsigned long next;
2065         int err;
2066
2067         p4d = p4d_alloc(mm, pgd, addr);
2068         if (!p4d)
2069                 return -ENOMEM;
2070         do {
2071                 next = p4d_addr_end(addr, end);
2072                 err = apply_to_pud_range(mm, p4d, addr, next, fn, data);
2073                 if (err)
2074                         break;
2075         } while (p4d++, addr = next, addr != end);
2076         return err;
2077 }
2078
2079 /*
2080  * Scan a region of virtual memory, filling in page tables as necessary
2081  * and calling a provided function on each leaf page table.
2082  */
2083 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2084                         unsigned long size, pte_fn_t fn, void *data)
2085 {
2086         pgd_t *pgd;
2087         unsigned long next;
2088         unsigned long end = addr + size;
2089         int err;
2090
2091         if (WARN_ON(addr >= end))
2092                 return -EINVAL;
2093
2094         pgd = pgd_offset(mm, addr);
2095         do {
2096                 next = pgd_addr_end(addr, end);
2097                 err = apply_to_p4d_range(mm, pgd, addr, next, fn, data);
2098                 if (err)
2099                         break;
2100         } while (pgd++, addr = next, addr != end);
2101
2102         return err;
2103 }
2104 EXPORT_SYMBOL_GPL(apply_to_page_range);
2105
2106 /*
2107  * handle_pte_fault chooses page fault handler according to an entry which was
2108  * read non-atomically.  Before making any commitment, on those architectures
2109  * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2110  * parts, do_swap_page must check under lock before unmapping the pte and
2111  * proceeding (but do_wp_page is only called after already making such a check;
2112  * and do_anonymous_page can safely check later on).
2113  */
2114 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2115                                 pte_t *page_table, pte_t orig_pte)
2116 {
2117         int same = 1;
2118 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2119         if (sizeof(pte_t) > sizeof(unsigned long)) {
2120                 spinlock_t *ptl = pte_lockptr(mm, pmd);
2121                 spin_lock(ptl);
2122                 same = pte_same(*page_table, orig_pte);
2123                 spin_unlock(ptl);
2124         }
2125 #endif
2126         pte_unmap(page_table);
2127         return same;
2128 }
2129
2130 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2131 {
2132         debug_dma_assert_idle(src);
2133
2134         /*
2135          * If the source page was a PFN mapping, we don't have
2136          * a "struct page" for it. We do a best-effort copy by
2137          * just copying from the original user address. If that
2138          * fails, we just zero-fill it. Live with it.
2139          */
2140         if (unlikely(!src)) {
2141                 void *kaddr = kmap_atomic(dst);
2142                 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2143
2144                 /*
2145                  * This really shouldn't fail, because the page is there
2146                  * in the page tables. But it might just be unreadable,
2147                  * in which case we just give up and fill the result with
2148                  * zeroes.
2149                  */
2150                 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2151                         clear_page(kaddr);
2152                 kunmap_atomic(kaddr);
2153                 flush_dcache_page(dst);
2154         } else
2155                 copy_user_highpage(dst, src, va, vma);
2156 }
2157
2158 static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2159 {
2160         struct file *vm_file = vma->vm_file;
2161
2162         if (vm_file)
2163                 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2164
2165         /*
2166          * Special mappings (e.g. VDSO) do not have any file so fake
2167          * a default GFP_KERNEL for them.
2168          */
2169         return GFP_KERNEL;
2170 }
2171
2172 /*
2173  * Notify the address space that the page is about to become writable so that
2174  * it can prohibit this or wait for the page to get into an appropriate state.
2175  *
2176  * We do this without the lock held, so that it can sleep if it needs to.
2177  */
2178 static int do_page_mkwrite(struct vm_fault *vmf)
2179 {
2180         int ret;
2181         struct page *page = vmf->page;
2182         unsigned int old_flags = vmf->flags;
2183
2184         vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2185
2186         ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2187         /* Restore original flags so that caller is not surprised */
2188         vmf->flags = old_flags;
2189         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2190                 return ret;
2191         if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2192                 lock_page(page);
2193                 if (!page->mapping) {
2194                         unlock_page(page);
2195                         return 0; /* retry */
2196                 }
2197                 ret |= VM_FAULT_LOCKED;
2198         } else
2199                 VM_BUG_ON_PAGE(!PageLocked(page), page);
2200         return ret;
2201 }
2202
2203 /*
2204  * Handle dirtying of a page in shared file mapping on a write fault.
2205  *
2206  * The function expects the page to be locked and unlocks it.
2207  */
2208 static void fault_dirty_shared_page(struct vm_area_struct *vma,
2209                                     struct page *page)
2210 {
2211         struct address_space *mapping;
2212         bool dirtied;
2213         bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2214
2215         dirtied = set_page_dirty(page);
2216         VM_BUG_ON_PAGE(PageAnon(page), page);
2217         /*
2218          * Take a local copy of the address_space - page.mapping may be zeroed
2219          * by truncate after unlock_page().   The address_space itself remains
2220          * pinned by vma->vm_file's reference.  We rely on unlock_page()'s
2221          * release semantics to prevent the compiler from undoing this copying.
2222          */
2223         mapping = page_rmapping(page);
2224         unlock_page(page);
2225
2226         if ((dirtied || page_mkwrite) && mapping) {
2227                 /*
2228                  * Some device drivers do not set page.mapping
2229                  * but still dirty their pages
2230                  */
2231                 balance_dirty_pages_ratelimited(mapping);
2232         }
2233
2234         if (!page_mkwrite)
2235                 file_update_time(vma->vm_file);
2236 }
2237
2238 /*
2239  * Handle write page faults for pages that can be reused in the current vma
2240  *
2241  * This can happen either due to the mapping being with the VM_SHARED flag,
2242  * or due to us being the last reference standing to the page. In either
2243  * case, all we need to do here is to mark the page as writable and update
2244  * any related book-keeping.
2245  */
2246 static inline void wp_page_reuse(struct vm_fault *vmf)
2247         __releases(vmf->ptl)
2248 {
2249         struct vm_area_struct *vma = vmf->vma;
2250         struct page *page = vmf->page;
2251         pte_t entry;
2252         /*
2253          * Clear the pages cpupid information as the existing
2254          * information potentially belongs to a now completely
2255          * unrelated process.
2256          */
2257         if (page)
2258                 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2259
2260         flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2261         entry = pte_mkyoung(vmf->orig_pte);
2262         entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2263         if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
2264                 update_mmu_cache(vma, vmf->address, vmf->pte);
2265         pte_unmap_unlock(vmf->pte, vmf->ptl);
2266 }
2267
2268 /*
2269  * Handle the case of a page which we actually need to copy to a new page.
2270  *
2271  * Called with mmap_sem locked and the old page referenced, but
2272  * without the ptl held.
2273  *
2274  * High level logic flow:
2275  *
2276  * - Allocate a page, copy the content of the old page to the new one.
2277  * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2278  * - Take the PTL. If the pte changed, bail out and release the allocated page
2279  * - If the pte is still the way we remember it, update the page table and all
2280  *   relevant references. This includes dropping the reference the page-table
2281  *   held to the old page, as well as updating the rmap.
2282  * - In any case, unlock the PTL and drop the reference we took to the old page.
2283  */
2284 static int wp_page_copy(struct vm_fault *vmf)
2285 {
2286         struct vm_area_struct *vma = vmf->vma;
2287         struct mm_struct *mm = vma->vm_mm;
2288         struct page *old_page = vmf->page;
2289         struct page *new_page = NULL;
2290         pte_t entry;
2291         int page_copied = 0;
2292         const unsigned long mmun_start = vmf->address & PAGE_MASK;
2293         const unsigned long mmun_end = mmun_start + PAGE_SIZE;
2294         struct mem_cgroup *memcg;
2295
2296         if (unlikely(anon_vma_prepare(vma)))
2297                 goto oom;
2298
2299         if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
2300                 new_page = alloc_zeroed_user_highpage_movable(vma,
2301                                                               vmf->address);
2302                 if (!new_page)
2303                         goto oom;
2304         } else {
2305                 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2306                                 vmf->address);
2307                 if (!new_page)
2308                         goto oom;
2309                 cow_user_page(new_page, old_page, vmf->address, vma);
2310         }
2311
2312         if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
2313                 goto oom_free_new;
2314
2315         __SetPageUptodate(new_page);
2316
2317         mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2318
2319         /*
2320          * Re-check the pte - we dropped the lock
2321          */
2322         vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
2323         if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2324                 if (old_page) {
2325                         if (!PageAnon(old_page)) {
2326                                 dec_mm_counter_fast(mm,
2327                                                 mm_counter_file(old_page));
2328                                 inc_mm_counter_fast(mm, MM_ANONPAGES);
2329                         }
2330                 } else {
2331                         inc_mm_counter_fast(mm, MM_ANONPAGES);
2332                 }
2333                 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2334                 entry = mk_pte(new_page, vma->vm_page_prot);
2335                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2336                 /*
2337                  * Clear the pte entry and flush it first, before updating the
2338                  * pte with the new entry. This will avoid a race condition
2339                  * seen in the presence of one thread doing SMC and another
2340                  * thread doing COW.
2341                  */
2342                 ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
2343                 page_add_new_anon_rmap(new_page, vma, vmf->address, false);
2344                 mem_cgroup_commit_charge(new_page, memcg, false, false);
2345                 lru_cache_add_active_or_unevictable(new_page, vma);
2346                 /*
2347                  * We call the notify macro here because, when using secondary
2348                  * mmu page tables (such as kvm shadow page tables), we want the
2349                  * new page to be mapped directly into the secondary page table.
2350                  */
2351                 set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
2352                 update_mmu_cache(vma, vmf->address, vmf->pte);
2353                 if (old_page) {
2354                         /*
2355                          * Only after switching the pte to the new page may
2356                          * we remove the mapcount here. Otherwise another
2357                          * process may come and find the rmap count decremented
2358                          * before the pte is switched to the new page, and
2359                          * "reuse" the old page writing into it while our pte
2360                          * here still points into it and can be read by other
2361                          * threads.
2362                          *
2363                          * The critical issue is to order this
2364                          * page_remove_rmap with the ptp_clear_flush above.
2365                          * Those stores are ordered by (if nothing else,)
2366                          * the barrier present in the atomic_add_negative
2367                          * in page_remove_rmap.
2368                          *
2369                          * Then the TLB flush in ptep_clear_flush ensures that
2370                          * no process can access the old page before the
2371                          * decremented mapcount is visible. And the old page
2372                          * cannot be reused until after the decremented
2373                          * mapcount is visible. So transitively, TLBs to
2374                          * old page will be flushed before it can be reused.
2375                          */
2376                         page_remove_rmap(old_page, false);
2377                 }
2378
2379                 /* Free the old page.. */
2380                 new_page = old_page;
2381                 page_copied = 1;
2382         } else {
2383                 mem_cgroup_cancel_charge(new_page, memcg, false);
2384         }
2385
2386         if (new_page)
2387                 put_page(new_page);
2388
2389         pte_unmap_unlock(vmf->pte, vmf->ptl);
2390         mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2391         if (old_page) {
2392                 /*
2393                  * Don't let another task, with possibly unlocked vma,
2394                  * keep the mlocked page.
2395                  */
2396                 if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2397                         lock_page(old_page);    /* LRU manipulation */
2398                         if (PageMlocked(old_page))
2399                                 munlock_vma_page(old_page);
2400                         unlock_page(old_page);
2401                 }
2402                 put_page(old_page);
2403         }
2404         return page_copied ? VM_FAULT_WRITE : 0;
2405 oom_free_new:
2406         put_page(new_page);
2407 oom:
2408         if (old_page)
2409                 put_page(old_page);
2410         return VM_FAULT_OOM;
2411 }
2412
2413 /**
2414  * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
2415  *                        writeable once the page is prepared
2416  *
2417  * @vmf: structure describing the fault
2418  *
2419  * This function handles all that is needed to finish a write page fault in a
2420  * shared mapping due to PTE being read-only once the mapped page is prepared.
2421  * It handles locking of PTE and modifying it. The function returns
2422  * VM_FAULT_WRITE on success, 0 when PTE got changed before we acquired PTE
2423  * lock.
2424  *
2425  * The function expects the page to be locked or other protection against
2426  * concurrent faults / writeback (such as DAX radix tree locks).
2427  */
2428 int finish_mkwrite_fault(struct vm_fault *vmf)
2429 {
2430         WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
2431         vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
2432                                        &vmf->ptl);
2433         /*
2434          * We might have raced with another page fault while we released the
2435          * pte_offset_map_lock.
2436          */
2437         if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2438                 pte_unmap_unlock(vmf->pte, vmf->ptl);
2439                 return VM_FAULT_NOPAGE;
2440         }
2441         wp_page_reuse(vmf);
2442         return 0;
2443 }
2444
2445 /*
2446  * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2447  * mapping
2448  */
2449 static int wp_pfn_shared(struct vm_fault *vmf)
2450 {
2451         struct vm_area_struct *vma = vmf->vma;
2452
2453         if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
2454                 int ret;
2455
2456                 pte_unmap_unlock(vmf->pte, vmf->ptl);
2457                 vmf->flags |= FAULT_FLAG_MKWRITE;
2458                 ret = vma->vm_ops->pfn_mkwrite(vmf);
2459                 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
2460                         return ret;
2461                 return finish_mkwrite_fault(vmf);
2462         }
2463         wp_page_reuse(vmf);
2464         return VM_FAULT_WRITE;
2465 }
2466
2467 static int wp_page_shared(struct vm_fault *vmf)
2468         __releases(vmf->ptl)
2469 {
2470         struct vm_area_struct *vma = vmf->vma;
2471
2472         get_page(vmf->page);
2473
2474         if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2475                 int tmp;
2476
2477                 pte_unmap_unlock(vmf->pte, vmf->ptl);
2478                 tmp = do_page_mkwrite(vmf);
2479                 if (unlikely(!tmp || (tmp &
2480                                       (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2481                         put_page(vmf->page);
2482                         return tmp;
2483                 }
2484                 tmp = finish_mkwrite_fault(vmf);
2485                 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2486                         unlock_page(vmf->page);
2487                         put_page(vmf->page);
2488                         return tmp;
2489                 }
2490         } else {
2491                 wp_page_reuse(vmf);
2492                 lock_page(vmf->page);
2493         }
2494         fault_dirty_shared_page(vma, vmf->page);
2495         put_page(vmf->page);
2496
2497         return VM_FAULT_WRITE;
2498 }
2499
2500 /*
2501  * This routine handles present pages, when users try to write
2502  * to a shared page. It is done by copying the page to a new address
2503  * and decrementing the shared-page counter for the old page.
2504  *
2505  * Note that this routine assumes that the protection checks have been
2506  * done by the caller (the low-level page fault routine in most cases).
2507  * Thus we can safely just mark it writable once we've done any necessary
2508  * COW.
2509  *
2510  * We also mark the page dirty at this point even though the page will
2511  * change only once the write actually happens. This avoids a few races,
2512  * and potentially makes it more efficient.
2513  *
2514  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2515  * but allow concurrent faults), with pte both mapped and locked.
2516  * We return with mmap_sem still held, but pte unmapped and unlocked.
2517  */
2518 static int do_wp_page(struct vm_fault *vmf)
2519         __releases(vmf->ptl)
2520 {
2521         struct vm_area_struct *vma = vmf->vma;
2522
2523         vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
2524         if (!vmf->page) {
2525                 /*
2526                  * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2527                  * VM_PFNMAP VMA.
2528                  *
2529                  * We should not cow pages in a shared writeable mapping.
2530                  * Just mark the pages writable and/or call ops->pfn_mkwrite.
2531                  */
2532                 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2533                                      (VM_WRITE|VM_SHARED))
2534                         return wp_pfn_shared(vmf);
2535
2536                 pte_unmap_unlock(vmf->pte, vmf->ptl);
2537                 return wp_page_copy(vmf);
2538         }
2539
2540         /*
2541          * Take out anonymous pages first, anonymous shared vmas are
2542          * not dirty accountable.
2543          */
2544         if (PageAnon(vmf->page) && !PageKsm(vmf->page)) {
2545                 int total_mapcount;
2546                 if (!trylock_page(vmf->page)) {
2547                         get_page(vmf->page);
2548                         pte_unmap_unlock(vmf->pte, vmf->ptl);
2549                         lock_page(vmf->page);
2550                         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2551                                         vmf->address, &vmf->ptl);
2552                         if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2553                                 unlock_page(vmf->page);
2554                                 pte_unmap_unlock(vmf->pte, vmf->ptl);
2555                                 put_page(vmf->page);
2556                                 return 0;
2557                         }
2558                         put_page(vmf->page);
2559                 }
2560                 if (reuse_swap_page(vmf->page, &total_mapcount)) {
2561                         if (total_mapcount == 1) {
2562                                 /*
2563                                  * The page is all ours. Move it to
2564                                  * our anon_vma so the rmap code will
2565                                  * not search our parent or siblings.
2566                                  * Protected against the rmap code by
2567                                  * the page lock.
2568                                  */
2569                                 page_move_anon_rmap(vmf->page, vma);
2570                         }
2571                         unlock_page(vmf->page);
2572                         wp_page_reuse(vmf);
2573                         return VM_FAULT_WRITE;
2574                 }
2575                 unlock_page(vmf->page);
2576         } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2577                                         (VM_WRITE|VM_SHARED))) {
2578                 return wp_page_shared(vmf);
2579         }
2580
2581         /*
2582          * Ok, we need to copy. Oh, well..
2583          */
2584         get_page(vmf->page);
2585
2586         pte_unmap_unlock(vmf->pte, vmf->ptl);
2587         return wp_page_copy(vmf);
2588 }
2589
2590 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2591                 unsigned long start_addr, unsigned long end_addr,
2592                 struct zap_details *details)
2593 {
2594         zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2595 }
2596
2597 static inline void unmap_mapping_range_tree(struct rb_root *root,
2598                                             struct zap_details *details)
2599 {
2600         struct vm_area_struct *vma;
2601         pgoff_t vba, vea, zba, zea;
2602
2603         vma_interval_tree_foreach(vma, root,
2604                         details->first_index, details->last_index) {
2605
2606                 vba = vma->vm_pgoff;
2607                 vea = vba + vma_pages(vma) - 1;
2608                 zba = details->first_index;
2609                 if (zba < vba)
2610                         zba = vba;
2611                 zea = details->last_index;
2612                 if (zea > vea)
2613                         zea = vea;
2614
2615                 unmap_mapping_range_vma(vma,
2616                         ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2617                         ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2618                                 details);
2619         }
2620 }
2621
2622 /**
2623  * unmap_mapping_range - unmap the portion of all mmaps in the specified
2624  * address_space corresponding to the specified page range in the underlying
2625  * file.
2626  *
2627  * @mapping: the address space containing mmaps to be unmapped.
2628  * @holebegin: byte in first page to unmap, relative to the start of
2629  * the underlying file.  This will be rounded down to a PAGE_SIZE
2630  * boundary.  Note that this is different from truncate_pagecache(), which
2631  * must keep the partial page.  In contrast, we must get rid of
2632  * partial pages.
2633  * @holelen: size of prospective hole in bytes.  This will be rounded
2634  * up to a PAGE_SIZE boundary.  A holelen of zero truncates to the
2635  * end of the file.
2636  * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2637  * but 0 when invalidating pagecache, don't throw away private data.
2638  */
2639 void unmap_mapping_range(struct address_space *mapping,
2640                 loff_t const holebegin, loff_t const holelen, int even_cows)
2641 {
2642         struct zap_details details = { };
2643         pgoff_t hba = holebegin >> PAGE_SHIFT;
2644         pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2645
2646         /* Check for overflow. */
2647         if (sizeof(holelen) > sizeof(hlen)) {
2648                 long long holeend =
2649                         (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2650                 if (holeend & ~(long long)ULONG_MAX)
2651                         hlen = ULONG_MAX - hba + 1;
2652         }
2653
2654         details.check_mapping = even_cows ? NULL : mapping;
2655         details.first_index = hba;
2656         details.last_index = hba + hlen - 1;
2657         if (details.last_index < details.first_index)
2658                 details.last_index = ULONG_MAX;
2659
2660         i_mmap_lock_write(mapping);
2661         if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
2662                 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2663         i_mmap_unlock_write(mapping);
2664 }
2665 EXPORT_SYMBOL(unmap_mapping_range);
2666
2667 /*
2668  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2669  * but allow concurrent faults), and pte mapped but not yet locked.
2670  * We return with pte unmapped and unlocked.
2671  *
2672  * We return with the mmap_sem locked or unlocked in the same cases
2673  * as does filemap_fault().
2674  */
2675 int do_swap_page(struct vm_fault *vmf)
2676 {
2677         struct vm_area_struct *vma = vmf->vma;
2678         struct page *page, *swapcache;
2679         struct mem_cgroup *memcg;
2680         swp_entry_t entry;
2681         pte_t pte;
2682         int locked;
2683         int exclusive = 0;
2684         int ret = 0;
2685
2686         if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
2687                 goto out;
2688
2689         entry = pte_to_swp_entry(vmf->orig_pte);
2690         if (unlikely(non_swap_entry(entry))) {
2691                 if (is_migration_entry(entry)) {
2692                         migration_entry_wait(vma->vm_mm, vmf->pmd,
2693                                              vmf->address);
2694                 } else if (is_hwpoison_entry(entry)) {
2695                         ret = VM_FAULT_HWPOISON;
2696                 } else {
2697                         print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
2698                         ret = VM_FAULT_SIGBUS;
2699                 }
2700                 goto out;
2701         }
2702         delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2703         page = lookup_swap_cache(entry);
2704         if (!page) {
2705                 page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, vma,
2706                                         vmf->address);
2707                 if (!page) {
2708                         /*
2709                          * Back out if somebody else faulted in this pte
2710                          * while we released the pte lock.
2711                          */
2712                         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2713                                         vmf->address, &vmf->ptl);
2714                         if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
2715                                 ret = VM_FAULT_OOM;
2716                         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2717                         goto unlock;
2718                 }
2719
2720                 /* Had to read the page from swap area: Major fault */
2721                 ret = VM_FAULT_MAJOR;
2722                 count_vm_event(PGMAJFAULT);
2723                 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
2724         } else if (PageHWPoison(page)) {
2725                 /*
2726                  * hwpoisoned dirty swapcache pages are kept for killing
2727                  * owner processes (which may be unknown at hwpoison time)
2728                  */
2729                 ret = VM_FAULT_HWPOISON;
2730                 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2731                 swapcache = page;
2732                 goto out_release;
2733         }
2734
2735         swapcache = page;
2736         locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
2737
2738         delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2739         if (!locked) {
2740                 ret |= VM_FAULT_RETRY;
2741                 goto out_release;
2742         }
2743
2744         /*
2745          * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2746          * release the swapcache from under us.  The page pin, and pte_same
2747          * test below, are not enough to exclude that.  Even if it is still
2748          * swapcache, we need to check that the page's swap has not changed.
2749          */
2750         if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2751                 goto out_page;
2752
2753         page = ksm_might_need_to_copy(page, vma, vmf->address);
2754         if (unlikely(!page)) {
2755                 ret = VM_FAULT_OOM;
2756                 page = swapcache;
2757                 goto out_page;
2758         }
2759
2760         if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL,
2761                                 &memcg, false)) {
2762                 ret = VM_FAULT_OOM;
2763                 goto out_page;
2764         }
2765
2766         /*
2767          * Back out if somebody else already faulted in this pte.
2768          */
2769         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
2770                         &vmf->ptl);
2771         if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
2772                 goto out_nomap;
2773
2774         if (unlikely(!PageUptodate(page))) {
2775                 ret = VM_FAULT_SIGBUS;
2776                 goto out_nomap;
2777         }
2778
2779         /*
2780          * The page isn't present yet, go ahead with the fault.
2781          *
2782          * Be careful about the sequence of operations here.
2783          * To get its accounting right, reuse_swap_page() must be called
2784          * while the page is counted on swap but not yet in mapcount i.e.
2785          * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2786          * must be called after the swap_free(), or it will never succeed.
2787          */
2788
2789         inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2790         dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
2791         pte = mk_pte(page, vma->vm_page_prot);
2792         if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
2793                 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2794                 vmf->flags &= ~FAULT_FLAG_WRITE;
2795                 ret |= VM_FAULT_WRITE;
2796                 exclusive = RMAP_EXCLUSIVE;
2797         }
2798         flush_icache_page(vma, page);
2799         if (pte_swp_soft_dirty(vmf->orig_pte))
2800                 pte = pte_mksoft_dirty(pte);
2801         set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
2802         vmf->orig_pte = pte;
2803         if (page == swapcache) {
2804                 do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
2805                 mem_cgroup_commit_charge(page, memcg, true, false);
2806                 activate_page(page);
2807         } else { /* ksm created a completely new copy */
2808                 page_add_new_anon_rmap(page, vma, vmf->address, false);
2809                 mem_cgroup_commit_charge(page, memcg, false, false);
2810                 lru_cache_add_active_or_unevictable(page, vma);
2811         }
2812
2813         swap_free(entry);
2814         if (mem_cgroup_swap_full(page) ||
2815             (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2816                 try_to_free_swap(page);
2817         unlock_page(page);
2818         if (page != swapcache) {
2819                 /*
2820                  * Hold the lock to avoid the swap entry to be reused
2821                  * until we take the PT lock for the pte_same() check
2822                  * (to avoid false positives from pte_same). For
2823                  * further safety release the lock after the swap_free
2824                  * so that the swap count won't change under a
2825                  * parallel locked swapcache.
2826                  */
2827                 unlock_page(swapcache);
2828                 put_page(swapcache);
2829         }
2830
2831         if (vmf->flags & FAULT_FLAG_WRITE) {
2832                 ret |= do_wp_page(vmf);
2833                 if (ret & VM_FAULT_ERROR)
2834                         ret &= VM_FAULT_ERROR;
2835                 goto out;
2836         }
2837
2838         /* No need to invalidate - it was non-present before */
2839         update_mmu_cache(vma, vmf->address, vmf->pte);
2840 unlock:
2841         pte_unmap_unlock(vmf->pte, vmf->ptl);
2842 out:
2843         return ret;
2844 out_nomap:
2845         mem_cgroup_cancel_charge(page, memcg, false);
2846         pte_unmap_unlock(vmf->pte, vmf->ptl);
2847 out_page:
2848         unlock_page(page);
2849 out_release:
2850         put_page(page);
2851         if (page != swapcache) {
2852                 unlock_page(swapcache);
2853                 put_page(swapcache);
2854         }
2855         return ret;
2856 }
2857
2858 /*
2859  * We enter with non-exclusive mmap_sem (to exclude vma changes,
2860  * but allow concurrent faults), and pte mapped but not yet locked.
2861  * We return with mmap_sem still held, but pte unmapped and unlocked.
2862  */
2863 static int do_anonymous_page(struct vm_fault *vmf)
2864 {
2865         struct vm_area_struct *vma = vmf->vma;
2866         struct mem_cgroup *memcg;
2867         struct page *page;
2868         pte_t entry;
2869
2870         /* File mapping without ->vm_ops ? */
2871         if (vma->vm_flags & VM_SHARED)
2872                 return VM_FAULT_SIGBUS;
2873
2874         /*
2875          * Use pte_alloc() instead of pte_alloc_map().  We can't run
2876          * pte_offset_map() on pmds where a huge pmd might be created
2877          * from a different thread.
2878          *
2879          * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
2880          * parallel threads are excluded by other means.
2881          *
2882          * Here we only have down_read(mmap_sem).
2883          */
2884         if (pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))
2885                 return VM_FAULT_OOM;
2886
2887         /* See the comment in pte_alloc_one_map() */
2888         if (unlikely(pmd_trans_unstable(vmf->pmd)))
2889                 return 0;
2890
2891         /* Use the zero-page for reads */
2892         if (!(vmf->flags & FAULT_FLAG_WRITE) &&
2893                         !mm_forbids_zeropage(vma->vm_mm)) {
2894                 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
2895                                                 vma->vm_page_prot));
2896                 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2897                                 vmf->address, &vmf->ptl);
2898                 if (!pte_none(*vmf->pte))
2899                         goto unlock;
2900                 /* Deliver the page fault to userland, check inside PT lock */
2901                 if (userfaultfd_missing(vma)) {
2902                         pte_unmap_unlock(vmf->pte, vmf->ptl);
2903                         return handle_userfault(vmf, VM_UFFD_MISSING);
2904                 }
2905                 goto setpte;
2906         }
2907
2908         /* Allocate our own private page. */
2909         if (unlikely(anon_vma_prepare(vma)))
2910                 goto oom;
2911         page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
2912         if (!page)
2913                 goto oom;
2914
2915         if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false))
2916                 goto oom_free_page;
2917
2918         /*
2919          * The memory barrier inside __SetPageUptodate makes sure that
2920          * preceeding stores to the page contents become visible before
2921          * the set_pte_at() write.
2922          */
2923         __SetPageUptodate(page);
2924
2925         entry = mk_pte(page, vma->vm_page_prot);
2926         if (vma->vm_flags & VM_WRITE)
2927                 entry = pte_mkwrite(pte_mkdirty(entry));
2928
2929         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
2930                         &vmf->ptl);
2931         if (!pte_none(*vmf->pte))
2932                 goto release;
2933
2934         /* Deliver the page fault to userland, check inside PT lock */
2935         if (userfaultfd_missing(vma)) {
2936                 pte_unmap_unlock(vmf->pte, vmf->ptl);
2937                 mem_cgroup_cancel_charge(page, memcg, false);
2938                 put_page(page);
2939                 return handle_userfault(vmf, VM_UFFD_MISSING);
2940         }
2941
2942         inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2943         page_add_new_anon_rmap(page, vma, vmf->address, false);
2944         mem_cgroup_commit_charge(page, memcg, false, false);
2945         lru_cache_add_active_or_unevictable(page, vma);
2946 setpte:
2947         set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
2948
2949         /* No need to invalidate - it was non-present before */
2950         update_mmu_cache(vma, vmf->address, vmf->pte);
2951 unlock:
2952         pte_unmap_unlock(vmf->pte, vmf->ptl);
2953         return 0;
2954 release:
2955         mem_cgroup_cancel_charge(page, memcg, false);
2956         put_page(page);
2957         goto unlock;
2958 oom_free_page:
2959         put_page(page);
2960 oom:
2961         return VM_FAULT_OOM;
2962 }
2963
2964 /*
2965  * The mmap_sem must have been held on entry, and may have been
2966  * released depending on flags and vma->vm_ops->fault() return value.
2967  * See filemap_fault() and __lock_page_retry().
2968  */
2969 static int __do_fault(struct vm_fault *vmf)
2970 {
2971         struct vm_area_struct *vma = vmf->vma;
2972         int ret;
2973
2974         ret = vma->vm_ops->fault(vmf);
2975         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
2976                             VM_FAULT_DONE_COW)))
2977                 return ret;
2978
2979         if (unlikely(PageHWPoison(vmf->page))) {
2980                 if (ret & VM_FAULT_LOCKED)
2981                         unlock_page(vmf->page);
2982                 put_page(vmf->page);
2983                 vmf->page = NULL;
2984                 return VM_FAULT_HWPOISON;
2985         }
2986
2987         if (unlikely(!(ret & VM_FAULT_LOCKED)))
2988                 lock_page(vmf->page);
2989         else
2990                 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
2991
2992         return ret;
2993 }
2994
2995 /*
2996  * The ordering of these checks is important for pmds with _PAGE_DEVMAP set.
2997  * If we check pmd_trans_unstable() first we will trip the bad_pmd() check
2998  * inside of pmd_none_or_trans_huge_or_clear_bad(). This will end up correctly
2999  * returning 1 but not before it spams dmesg with the pmd_clear_bad() output.
3000  */
3001 static int pmd_devmap_trans_unstable(pmd_t *pmd)
3002 {
3003         return pmd_devmap(*pmd) || pmd_trans_unstable(pmd);
3004 }
3005
3006 static int pte_alloc_one_map(struct vm_fault *vmf)
3007 {
3008         struct vm_area_struct *vma = vmf->vma;
3009
3010         if (!pmd_none(*vmf->pmd))
3011                 goto map_pte;
3012         if (vmf->prealloc_pte) {
3013                 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3014                 if (unlikely(!pmd_none(*vmf->pmd))) {
3015                         spin_unlock(vmf->ptl);
3016                         goto map_pte;
3017                 }
3018
3019                 atomic_long_inc(&vma->vm_mm->nr_ptes);
3020                 pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3021                 spin_unlock(vmf->ptl);
3022                 vmf->prealloc_pte = NULL;
3023         } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))) {
3024                 return VM_FAULT_OOM;
3025         }
3026 map_pte:
3027         /*
3028          * If a huge pmd materialized under us just retry later.  Use
3029          * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead of
3030          * pmd_trans_huge() to ensure the pmd didn't become pmd_trans_huge
3031          * under us and then back to pmd_none, as a result of MADV_DONTNEED
3032          * running immediately after a huge pmd fault in a different thread of
3033          * this mm, in turn leading to a misleading pmd_trans_huge() retval.
3034          * All we have to ensure is that it is a regular pmd that we can walk
3035          * with pte_offset_map() and we can do that through an atomic read in
3036          * C, which is what pmd_trans_unstable() provides.
3037          */
3038         if (pmd_devmap_trans_unstable(vmf->pmd))
3039                 return VM_FAULT_NOPAGE;
3040
3041         /*
3042          * At this point we know that our vmf->pmd points to a page of ptes
3043          * and it cannot become pmd_none(), pmd_devmap() or pmd_trans_huge()
3044          * for the duration of the fault.  If a racing MADV_DONTNEED runs and
3045          * we zap the ptes pointed to by our vmf->pmd, the vmf->ptl will still
3046          * be valid and we will re-check to make sure the vmf->pte isn't
3047          * pte_none() under vmf->ptl protection when we return to
3048          * alloc_set_pte().
3049          */
3050         vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3051                         &vmf->ptl);
3052         return 0;
3053 }
3054
3055 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3056
3057 #define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
3058 static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
3059                 unsigned long haddr)
3060 {
3061         if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
3062                         (vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK))
3063                 return false;
3064         if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
3065                 return false;
3066         return true;
3067 }
3068
3069 static void deposit_prealloc_pte(struct vm_fault *vmf)
3070 {
3071         struct vm_area_struct *vma = vmf->vma;
3072
3073         pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3074         /*
3075          * We are going to consume the prealloc table,
3076          * count that as nr_ptes.
3077          */
3078         atomic_long_inc(&vma->vm_mm->nr_ptes);
3079         vmf->prealloc_pte = NULL;
3080 }
3081
3082 static int do_set_pmd(struct vm_fault *vmf, struct page *page)
3083 {
3084         struct vm_area_struct *vma = vmf->vma;
3085         bool write = vmf->flags & FAULT_FLAG_WRITE;
3086         unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
3087         pmd_t entry;
3088         int i, ret;
3089
3090         if (!transhuge_vma_suitable(vma, haddr))
3091                 return VM_FAULT_FALLBACK;
3092
3093         ret = VM_FAULT_FALLBACK;
3094         page = compound_head(page);
3095
3096         /*
3097          * Archs like ppc64 need additonal space to store information
3098          * related to pte entry. Use the preallocated table for that.
3099          */
3100         if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
3101                 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm, vmf->address);
3102                 if (!vmf->prealloc_pte)
3103                         return VM_FAULT_OOM;
3104                 smp_wmb(); /* See comment in __pte_alloc() */
3105         }
3106
3107         vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3108         if (unlikely(!pmd_none(*vmf->pmd)))
3109                 goto out;
3110
3111         for (i = 0; i < HPAGE_PMD_NR; i++)
3112                 flush_icache_page(vma, page + i);
3113
3114         entry = mk_huge_pmd(page, vma->vm_page_prot);
3115         if (write)
3116                 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
3117
3118         add_mm_counter(vma->vm_mm, MM_FILEPAGES, HPAGE_PMD_NR);
3119         page_add_file_rmap(page, true);
3120         /*
3121          * deposit and withdraw with pmd lock held
3122          */
3123         if (arch_needs_pgtable_deposit())
3124                 deposit_prealloc_pte(vmf);
3125
3126         set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
3127
3128         update_mmu_cache_pmd(vma, haddr, vmf->pmd);
3129
3130         /* fault is handled */
3131         ret = 0;
3132         count_vm_event(THP_FILE_MAPPED);
3133 out:
3134         spin_unlock(vmf->ptl);
3135         return ret;
3136 }
3137 #else
3138 static int do_set_pmd(struct vm_fault *vmf, struct page *page)
3139 {
3140         BUILD_BUG();
3141         return 0;
3142 }
3143 #endif
3144
3145 /**
3146  * alloc_set_pte - setup new PTE entry for given page and add reverse page
3147  * mapping. If needed, the fucntion allocates page table or use pre-allocated.
3148  *
3149  * @vmf: fault environment
3150  * @memcg: memcg to charge page (only for private mappings)
3151  * @page: page to map
3152  *
3153  * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on
3154  * return.
3155  *
3156  * Target users are page handler itself and implementations of
3157  * vm_ops->map_pages.
3158  */
3159 int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
3160                 struct page *page)
3161 {
3162         struct vm_area_struct *vma = vmf->vma;
3163         bool write = vmf->flags & FAULT_FLAG_WRITE;
3164         pte_t entry;
3165         int ret;
3166
3167         if (pmd_none(*vmf->pmd) && PageTransCompound(page) &&
3168                         IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
3169                 /* THP on COW? */
3170                 VM_BUG_ON_PAGE(memcg, page);
3171
3172                 ret = do_set_pmd(vmf, page);
3173                 if (ret != VM_FAULT_FALLBACK)
3174                         return ret;
3175         }
3176
3177         if (!vmf->pte) {
3178                 ret = pte_alloc_one_map(vmf);
3179                 if (ret)
3180                         return ret;
3181         }
3182
3183         /* Re-check under ptl */
3184         if (unlikely(!pte_none(*vmf->pte)))
3185                 return VM_FAULT_NOPAGE;
3186
3187         flush_icache_page(vma, page);
3188         entry = mk_pte(page, vma->vm_page_prot);
3189         if (write)
3190                 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3191         /* copy-on-write page */
3192         if (write && !(vma->vm_flags & VM_SHARED)) {
3193                 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3194                 page_add_new_anon_rmap(page, vma, vmf->address, false);
3195                 mem_cgroup_commit_charge(page, memcg, false, false);
3196                 lru_cache_add_active_or_unevictable(page, vma);
3197         } else {
3198                 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
3199                 page_add_file_rmap(page, false);
3200         }
3201         set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3202
3203         /* no need to invalidate: a not-present page won't be cached */
3204         update_mmu_cache(vma, vmf->address, vmf->pte);
3205
3206         return 0;
3207 }
3208
3209
3210 /**
3211  * finish_fault - finish page fault once we have prepared the page to fault
3212  *
3213  * @vmf: structure describing the fault
3214  *
3215  * This function handles all that is needed to finish a page fault once the
3216  * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
3217  * given page, adds reverse page mapping, handles memcg charges and LRU
3218  * addition. The function returns 0 on success, VM_FAULT_ code in case of
3219  * error.
3220  *
3221  * The function expects the page to be locked and on success it consumes a
3222  * reference of a page being mapped (for the PTE which maps it).
3223  */
3224 int finish_fault(struct vm_fault *vmf)
3225 {
3226         struct page *page;
3227         int ret;
3228
3229         /* Did we COW the page? */
3230         if ((vmf->flags & FAULT_FLAG_WRITE) &&
3231             !(vmf->vma->vm_flags & VM_SHARED))
3232                 page = vmf->cow_page;
3233         else
3234                 page = vmf->page;
3235         ret = alloc_set_pte(vmf, vmf->memcg, page);
3236         if (vmf->pte)
3237                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3238         return ret;
3239 }
3240
3241 static unsigned long fault_around_bytes __read_mostly =
3242         rounddown_pow_of_two(65536);
3243
3244 #ifdef CONFIG_DEBUG_FS
3245 static int fault_around_bytes_get(void *data, u64 *val)
3246 {
3247         *val = fault_around_bytes;
3248         return 0;
3249 }
3250
3251 /*
3252  * fault_around_pages() and fault_around_mask() expects fault_around_bytes
3253  * rounded down to nearest page order. It's what do_fault_around() expects to
3254  * see.
3255  */
3256 static int fault_around_bytes_set(void *data, u64 val)
3257 {
3258         if (val / PAGE_SIZE > PTRS_PER_PTE)
3259                 return -EINVAL;
3260         if (val > PAGE_SIZE)
3261                 fault_around_bytes = rounddown_pow_of_two(val);
3262         else
3263                 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
3264         return 0;
3265 }
3266 DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
3267                 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3268
3269 static int __init fault_around_debugfs(void)
3270 {
3271         void *ret;
3272
3273         ret = debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
3274                         &fault_around_bytes_fops);
3275         if (!ret)
3276                 pr_warn("Failed to create fault_around_bytes in debugfs");
3277         return 0;
3278 }
3279 late_initcall(fault_around_debugfs);
3280 #endif
3281
3282 /*
3283  * do_fault_around() tries to map few pages around the fault address. The hope
3284  * is that the pages will be needed soon and this will lower the number of
3285  * faults to handle.
3286  *
3287  * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3288  * not ready to be mapped: not up-to-date, locked, etc.
3289  *
3290  * This function is called with the page table lock taken. In the split ptlock
3291  * case the page table lock only protects only those entries which belong to
3292  * the page table corresponding to the fault address.
3293  *
3294  * This function doesn't cross the VMA boundaries, in order to call map_pages()
3295  * only once.
3296  *
3297  * fault_around_pages() defines how many pages we'll try to map.
3298  * do_fault_around() expects it to return a power of two less than or equal to
3299  * PTRS_PER_PTE.
3300  *
3301  * The virtual address of the area that we map is naturally aligned to the
3302  * fault_around_pages() value (and therefore to page order).  This way it's
3303  * easier to guarantee that we don't cross page table boundaries.
3304  */
3305 static int do_fault_around(struct vm_fault *vmf)
3306 {
3307         unsigned long address = vmf->address, nr_pages, mask;
3308         pgoff_t start_pgoff = vmf->pgoff;
3309         pgoff_t end_pgoff;
3310         int off, ret = 0;
3311
3312         nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3313         mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
3314
3315         vmf->address = max(address & mask, vmf->vma->vm_start);
3316         off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
3317         start_pgoff -= off;
3318
3319         /*
3320          *  end_pgoff is either end of page table or end of vma
3321          *  or fault_around_pages() from start_pgoff, depending what is nearest.
3322          */
3323         end_pgoff = start_pgoff -
3324                 ((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3325                 PTRS_PER_PTE - 1;
3326         end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
3327                         start_pgoff + nr_pages - 1);
3328
3329         if (pmd_none(*vmf->pmd)) {
3330                 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm,
3331                                                   vmf->address);
3332                 if (!vmf->prealloc_pte)
3333                         goto out;
3334                 smp_wmb(); /* See comment in __pte_alloc() */
3335         }
3336
3337         vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
3338
3339         /* Huge page is mapped? Page fault is solved */
3340         if (pmd_trans_huge(*vmf->pmd)) {
3341                 ret = VM_FAULT_NOPAGE;
3342                 goto out;
3343         }
3344
3345         /* ->map_pages() haven't done anything useful. Cold page cache? */
3346         if (!vmf->pte)
3347                 goto out;
3348
3349         /* check if the page fault is solved */
3350         vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
3351         if (!pte_none(*vmf->pte))
3352                 ret = VM_FAULT_NOPAGE;
3353         pte_unmap_unlock(vmf->pte, vmf->ptl);
3354 out:
3355         vmf->address = address;
3356         vmf->pte = NULL;
3357         return ret;
3358 }
3359
3360 static int do_read_fault(struct vm_fault *vmf)
3361 {
3362         struct vm_area_struct *vma = vmf->vma;
3363         int ret = 0;
3364
3365         /*
3366          * Let's call ->map_pages() first and use ->fault() as fallback
3367          * if page by the offset is not ready to be mapped (cold cache or
3368          * something).
3369          */
3370         if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3371                 ret = do_fault_around(vmf);
3372                 if (ret)
3373                         return ret;
3374         }
3375
3376         ret = __do_fault(vmf);
3377         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3378                 return ret;
3379
3380         ret |= finish_fault(vmf);
3381         unlock_page(vmf->page);
3382         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3383                 put_page(vmf->page);
3384         return ret;
3385 }
3386
3387 static int do_cow_fault(struct vm_fault *vmf)
3388 {
3389         struct vm_area_struct *vma = vmf->vma;
3390         int ret;
3391
3392         if (unlikely(anon_vma_prepare(vma)))
3393                 return VM_FAULT_OOM;
3394
3395         vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
3396         if (!vmf->cow_page)
3397                 return VM_FAULT_OOM;
3398
3399         if (mem_cgroup_try_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
3400                                 &vmf->memcg, false)) {
3401                 put_page(vmf->cow_page);
3402                 return VM_FAULT_OOM;
3403         }
3404
3405         ret = __do_fault(vmf);
3406         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3407                 goto uncharge_out;
3408         if (ret & VM_FAULT_DONE_COW)
3409                 return ret;
3410
3411         copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
3412         __SetPageUptodate(vmf->cow_page);
3413
3414         ret |= finish_fault(vmf);
3415         unlock_page(vmf->page);
3416         put_page(vmf->page);
3417         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3418                 goto uncharge_out;
3419         return ret;
3420 uncharge_out:
3421         mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false);
3422         put_page(vmf->cow_page);
3423         return ret;
3424 }
3425
3426 static int do_shared_fault(struct vm_fault *vmf)
3427 {
3428         struct vm_area_struct *vma = vmf->vma;
3429         int ret, tmp;
3430
3431         ret = __do_fault(vmf);
3432         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3433                 return ret;
3434
3435         /*
3436          * Check if the backing address space wants to know that the page is
3437          * about to become writable
3438          */
3439         if (vma->vm_ops->page_mkwrite) {
3440                 unlock_page(vmf->page);
3441                 tmp = do_page_mkwrite(vmf);
3442                 if (unlikely(!tmp ||
3443                                 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3444                         put_page(vmf->page);
3445                         return tmp;
3446                 }
3447         }
3448
3449         ret |= finish_fault(vmf);
3450         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3451                                         VM_FAULT_RETRY))) {
3452                 unlock_page(vmf->page);
3453                 put_page(vmf->page);
3454                 return ret;
3455         }
3456
3457         fault_dirty_shared_page(vma, vmf->page);
3458         return ret;
3459 }
3460
3461 /*
3462  * We enter with non-exclusive mmap_sem (to exclude vma changes,
3463  * but allow concurrent faults).
3464  * The mmap_sem may have been released depending on flags and our
3465  * return value.  See filemap_fault() and __lock_page_or_retry().
3466  */
3467 static int do_fault(struct vm_fault *vmf)
3468 {
3469         struct vm_area_struct *vma = vmf->vma;
3470         int ret;
3471
3472         /* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
3473         if (!vma->vm_ops->fault)
3474                 ret = VM_FAULT_SIGBUS;
3475         else if (!(vmf->flags & FAULT_FLAG_WRITE))
3476                 ret = do_read_fault(vmf);
3477         else if (!(vma->vm_flags & VM_SHARED))
3478                 ret = do_cow_fault(vmf);
3479         else
3480                 ret = do_shared_fault(vmf);
3481
3482         /* preallocated pagetable is unused: free it */
3483         if (vmf->prealloc_pte) {
3484                 pte_free(vma->vm_mm, vmf->prealloc_pte);
3485                 vmf->prealloc_pte = NULL;
3486         }
3487         return ret;
3488 }
3489
3490 static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3491                                 unsigned long addr, int page_nid,
3492                                 int *flags)
3493 {
3494         get_page(page);
3495
3496         count_vm_numa_event(NUMA_HINT_FAULTS);
3497         if (page_nid == numa_node_id()) {
3498                 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3499                 *flags |= TNF_FAULT_LOCAL;
3500         }
3501
3502         return mpol_misplaced(page, vma, addr);
3503 }
3504
3505 static int do_numa_page(struct vm_fault *vmf)
3506 {
3507         struct vm_area_struct *vma = vmf->vma;
3508         struct page *page = NULL;
3509         int page_nid = -1;
3510         int last_cpupid;
3511         int target_nid;
3512         bool migrated = false;
3513         pte_t pte;
3514         bool was_writable = pte_savedwrite(vmf->orig_pte);
3515         int flags = 0;
3516
3517         /*
3518          * The "pte" at this point cannot be used safely without
3519          * validation through pte_unmap_same(). It's of NUMA type but
3520          * the pfn may be screwed if the read is non atomic.
3521          */
3522         vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
3523         spin_lock(vmf->ptl);
3524         if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
3525                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3526                 goto out;
3527         }
3528
3529         /*
3530          * Make it present again, Depending on how arch implementes non
3531          * accessible ptes, some can allow access by kernel mode.
3532          */
3533         pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte);
3534         pte = pte_modify(pte, vma->vm_page_prot);
3535         pte = pte_mkyoung(pte);
3536         if (was_writable)
3537                 pte = pte_mkwrite(pte);
3538         ptep_modify_prot_commit(vma->vm_mm, vmf->address, vmf->pte, pte);
3539         update_mmu_cache(vma, vmf->address, vmf->pte);
3540
3541         page = vm_normal_page(vma, vmf->address, pte);
3542         if (!page) {
3543                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3544                 return 0;
3545         }
3546
3547         /* TODO: handle PTE-mapped THP */
3548         if (PageCompound(page)) {
3549                 pte_unmap_unlock(vmf->pte, vmf->ptl);
3550                 return 0;
3551         }
3552
3553         /*
3554          * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
3555          * much anyway since they can be in shared cache state. This misses
3556          * the case where a mapping is writable but the process never writes
3557          * to it but pte_write gets cleared during protection updates and
3558          * pte_dirty has unpredictable behaviour between PTE scan updates,
3559          * background writeback, dirty balancing and application behaviour.
3560          */
3561         if (!pte_write(pte))
3562                 flags |= TNF_NO_GROUP;
3563
3564         /*
3565          * Flag if the page is shared between multiple address spaces. This
3566          * is later used when determining whether to group tasks together
3567          */
3568         if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3569                 flags |= TNF_SHARED;
3570
3571         last_cpupid = page_cpupid_last(page);
3572         page_nid = page_to_nid(page);
3573         target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
3574                         &flags);
3575         pte_unmap_unlock(vmf->pte, vmf->ptl);
3576         if (target_nid == -1) {
3577                 put_page(page);
3578                 goto out;
3579         }
3580
3581         /* Migrate to the requested node */
3582         migrated = migrate_misplaced_page(page, vma, target_nid);
3583         if (migrated) {
3584                 page_nid = target_nid;
3585                 flags |= TNF_MIGRATED;
3586         } else
3587                 flags |= TNF_MIGRATE_FAIL;
3588
3589 out:
3590         if (page_nid != -1)
3591                 task_numa_fault(last_cpupid, page_nid, 1, flags);
3592         return 0;
3593 }
3594
3595 static inline int create_huge_pmd(struct vm_fault *vmf)
3596 {
3597         if (vma_is_anonymous(vmf->vma))
3598                 return do_huge_pmd_anonymous_page(vmf);
3599         if (vmf->vma->vm_ops->huge_fault)
3600                 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3601         return VM_FAULT_FALLBACK;
3602 }
3603
3604 static int wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
3605 {
3606         if (vma_is_anonymous(vmf->vma))
3607                 return do_huge_pmd_wp_page(vmf, orig_pmd);
3608         if (vmf->vma->vm_ops->huge_fault)
3609                 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3610
3611         /* COW handled on pte level: split pmd */
3612         VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);
3613         __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
3614
3615         return VM_FAULT_FALLBACK;
3616 }
3617
3618 static inline bool vma_is_accessible(struct vm_area_struct *vma)
3619 {
3620         return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
3621 }
3622
3623 static int create_huge_pud(struct vm_fault *vmf)
3624 {
3625 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3626         /* No support for anonymous transparent PUD pages yet */
3627         if (vma_is_anonymous(vmf->vma))
3628                 return VM_FAULT_FALLBACK;
3629         if (vmf->vma->vm_ops->huge_fault)
3630                 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3631 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3632         return VM_FAULT_FALLBACK;
3633 }
3634
3635 static int wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
3636 {
3637 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3638         /* No support for anonymous transparent PUD pages yet */
3639         if (vma_is_anonymous(vmf->vma))
3640                 return VM_FAULT_FALLBACK;
3641         if (vmf->vma->vm_ops->huge_fault)
3642                 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3643 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3644         return VM_FAULT_FALLBACK;
3645 }
3646
3647 /*
3648  * These routines also need to handle stuff like marking pages dirty
3649  * and/or accessed for architectures that don't do it in hardware (most
3650  * RISC architectures).  The early dirtying is also good on the i386.
3651  *
3652  * There is also a hook called "update_mmu_cache()" that architectures
3653  * with external mmu caches can use to update those (ie the Sparc or
3654  * PowerPC hashed page tables that act as extended TLBs).
3655  *
3656  * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
3657  * concurrent faults).
3658  *
3659  * The mmap_sem may have been released depending on flags and our return value.
3660  * See filemap_fault() and __lock_page_or_retry().
3661  */
3662 static int handle_pte_fault(struct vm_fault *vmf)
3663 {
3664         pte_t entry;
3665
3666         if (unlikely(pmd_none(*vmf->pmd))) {
3667                 /*
3668                  * Leave __pte_alloc() until later: because vm_ops->fault may
3669                  * want to allocate huge page, and if we expose page table
3670                  * for an instant, it will be difficult to retract from
3671                  * concurrent faults and from rmap lookups.
3672                  */
3673                 vmf->pte = NULL;
3674         } else {
3675                 /* See comment in pte_alloc_one_map() */
3676                 if (pmd_devmap_trans_unstable(vmf->pmd))
3677                         return 0;
3678                 /*
3679                  * A regular pmd is established and it can't morph into a huge
3680                  * pmd from under us anymore at this point because we hold the
3681                  * mmap_sem read mode and khugepaged takes it in write mode.
3682                  * So now it's safe to run pte_offset_map().
3683                  */
3684                 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
3685                 vmf->orig_pte = *vmf->pte;
3686
3687                 /*
3688                  * some architectures can have larger ptes than wordsize,
3689                  * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
3690                  * CONFIG_32BIT=y, so READ_ONCE or ACCESS_ONCE cannot guarantee
3691                  * atomic accesses.  The code below just needs a consistent
3692                  * view for the ifs and we later double check anyway with the
3693                  * ptl lock held. So here a barrier will do.
3694                  */
3695                 barrier();
3696                 if (pte_none(vmf->orig_pte)) {
3697                         pte_unmap(vmf->pte);
3698                         vmf->pte = NULL;
3699                 }
3700         }
3701
3702         if (!vmf->pte) {
3703                 if (vma_is_anonymous(vmf->vma))
3704                         return do_anonymous_page(vmf);
3705                 else
3706                         return do_fault(vmf);
3707         }
3708
3709         if (!pte_present(vmf->orig_pte))
3710                 return do_swap_page(vmf);
3711
3712         if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
3713                 return do_numa_page(vmf);
3714
3715         vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
3716         spin_lock(vmf->ptl);
3717         entry = vmf->orig_pte;
3718         if (unlikely(!pte_same(*vmf->pte, entry)))
3719                 goto unlock;
3720         if (vmf->flags & FAULT_FLAG_WRITE) {
3721                 if (!pte_write(entry))
3722                         return do_wp_page(vmf);
3723                 entry = pte_mkdirty(entry);
3724         }
3725         entry = pte_mkyoung(entry);
3726         if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
3727                                 vmf->flags & FAULT_FLAG_WRITE)) {
3728                 update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
3729         } else {
3730                 /*
3731                  * This is needed only for protection faults but the arch code
3732                  * is not yet telling us if this is a protection fault or not.
3733                  * This still avoids useless tlb flushes for .text page faults
3734                  * with threads.
3735                  */
3736                 if (vmf->flags & FAULT_FLAG_WRITE)
3737                         flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
3738         }
3739 unlock:
3740         pte_unmap_unlock(vmf->pte, vmf->ptl);
3741         return 0;
3742 }
3743
3744 /*
3745  * By the time we get here, we already hold the mm semaphore
3746  *
3747  * The mmap_sem may have been released depending on flags and our
3748  * return value.  See filemap_fault() and __lock_page_or_retry().
3749  */
3750 static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
3751                 unsigned int flags)
3752 {
3753         struct vm_fault vmf = {
3754                 .vma = vma,
3755                 .address = address & PAGE_MASK,
3756                 .flags = flags,
3757                 .pgoff = linear_page_index(vma, address),
3758                 .gfp_mask = __get_fault_gfp_mask(vma),
3759         };
3760         struct mm_struct *mm = vma->vm_mm;
3761         pgd_t *pgd;
3762         p4d_t *p4d;
3763         int ret;
3764
3765         pgd = pgd_offset(mm, address);
3766         p4d = p4d_alloc(mm, pgd, address);
3767         if (!p4d)
3768                 return VM_FAULT_OOM;
3769
3770         vmf.pud = pud_alloc(mm, p4d, address);
3771         if (!vmf.pud)
3772                 return VM_FAULT_OOM;
3773         if (pud_none(*vmf.pud) && transparent_hugepage_enabled(vma)) {
3774                 ret = create_huge_pud(&vmf);
3775                 if (!(ret & VM_FAULT_FALLBACK))
3776                         return ret;
3777         } else {
3778                 pud_t orig_pud = *vmf.pud;
3779
3780                 barrier();
3781                 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
3782                         unsigned int dirty = flags & FAULT_FLAG_WRITE;
3783
3784                         /* NUMA case for anonymous PUDs would go here */
3785
3786                         if (dirty && !pud_write(orig_pud)) {
3787                                 ret = wp_huge_pud(&vmf, orig_pud);
3788                                 if (!(ret & VM_FAULT_FALLBACK))
3789                                         return ret;
3790                         } else {
3791                                 huge_pud_set_accessed(&vmf, orig_pud);
3792                                 return 0;
3793                         }
3794                 }
3795         }
3796
3797         vmf.pmd = pmd_alloc(mm, vmf.pud, address);
3798         if (!vmf.pmd)
3799                 return VM_FAULT_OOM;
3800         if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) {
3801                 ret = create_huge_pmd(&vmf);
3802                 if (!(ret & VM_FAULT_FALLBACK))
3803                         return ret;
3804         } else {
3805                 pmd_t orig_pmd = *vmf.pmd;
3806
3807                 barrier();
3808                 if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
3809                         if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
3810                                 return do_huge_pmd_numa_page(&vmf, orig_pmd);
3811
3812                         if ((vmf.flags & FAULT_FLAG_WRITE) &&
3813                                         !pmd_write(orig_pmd)) {
3814                                 ret = wp_huge_pmd(&vmf, orig_pmd);
3815                                 if (!(ret & VM_FAULT_FALLBACK))
3816                                         return ret;
3817                         } else {
3818                                 huge_pmd_set_accessed(&vmf, orig_pmd);
3819                                 return 0;
3820                         }
3821                 }
3822         }
3823
3824         return handle_pte_fault(&vmf);
3825 }
3826
3827 /*
3828  * By the time we get here, we already hold the mm semaphore
3829  *
3830  * The mmap_sem may have been released depending on flags and our
3831  * return value.  See filemap_fault() and __lock_page_or_retry().
3832  */
3833 int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
3834                 unsigned int flags)
3835 {
3836         int ret;
3837
3838         __set_current_state(TASK_RUNNING);
3839
3840         count_vm_event(PGFAULT);
3841         count_memcg_event_mm(vma->vm_mm, PGFAULT);
3842
3843         /* do counter updates before entering really critical section. */
3844         check_sync_rss_stat(current);
3845
3846         /*
3847          * Enable the memcg OOM handling for faults triggered in user
3848          * space.  Kernel faults are handled more gracefully.
3849          */
3850         if (flags & FAULT_FLAG_USER)
3851                 mem_cgroup_oom_enable();
3852
3853         if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
3854                                             flags & FAULT_FLAG_INSTRUCTION,
3855                                             flags & FAULT_FLAG_REMOTE))
3856                 return VM_FAULT_SIGSEGV;
3857
3858         if (unlikely(is_vm_hugetlb_page(vma)))
3859                 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
3860         else
3861                 ret = __handle_mm_fault(vma, address, flags);
3862
3863         if (flags & FAULT_FLAG_USER) {
3864                 mem_cgroup_oom_disable();
3865                 /*
3866                  * The task may have entered a memcg OOM situation but
3867                  * if the allocation error was handled gracefully (no
3868                  * VM_FAULT_OOM), there is no need to kill anything.
3869                  * Just clean up the OOM state peacefully.
3870                  */
3871                 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
3872                         mem_cgroup_oom_synchronize(false);
3873         }
3874
3875         /*
3876          * This mm has been already reaped by the oom reaper and so the
3877          * refault cannot be trusted in general. Anonymous refaults would
3878          * lose data and give a zero page instead e.g. This is especially
3879          * problem for use_mm() because regular tasks will just die and
3880          * the corrupted data will not be visible anywhere while kthread
3881          * will outlive the oom victim and potentially propagate the date
3882          * further.
3883          */
3884         if (unlikely((current->flags & PF_KTHREAD) && !(ret & VM_FAULT_ERROR)
3885                                 && test_bit(MMF_UNSTABLE, &vma->vm_mm->flags)))
3886                 ret = VM_FAULT_SIGBUS;
3887
3888         return ret;
3889 }
3890 EXPORT_SYMBOL_GPL(handle_mm_fault);
3891
3892 #ifndef __PAGETABLE_P4D_FOLDED
3893 /*
3894  * Allocate p4d page table.
3895  * We've already handled the fast-path in-line.
3896  */
3897 int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3898 {
3899         p4d_t *new = p4d_alloc_one(mm, address);
3900         if (!new)
3901                 return -ENOMEM;
3902
3903         smp_wmb(); /* See comment in __pte_alloc */
3904
3905         spin_lock(&mm->page_table_lock);
3906         if (pgd_present(*pgd))          /* Another has populated it */
3907                 p4d_free(mm, new);
3908         else
3909                 pgd_populate(mm, pgd, new);
3910         spin_unlock(&mm->page_table_lock);
3911         return 0;
3912 }
3913 #endif /* __PAGETABLE_P4D_FOLDED */
3914
3915 #ifndef __PAGETABLE_PUD_FOLDED
3916 /*
3917  * Allocate page upper directory.
3918  * We've already handled the fast-path in-line.
3919  */
3920 int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
3921 {
3922         pud_t *new = pud_alloc_one(mm, address);
3923         if (!new)
3924                 return -ENOMEM;
3925
3926         smp_wmb(); /* See comment in __pte_alloc */
3927
3928         spin_lock(&mm->page_table_lock);
3929 #ifndef __ARCH_HAS_5LEVEL_HACK
3930         if (p4d_present(*p4d))          /* Another has populated it */
3931                 pud_free(mm, new);
3932         else
3933                 p4d_populate(mm, p4d, new);
3934 #else
3935         if (pgd_present(*p4d))          /* Another has populated it */
3936                 pud_free(mm, new);
3937         else
3938                 pgd_populate(mm, p4d, new);
3939 #endif /* __ARCH_HAS_5LEVEL_HACK */
3940         spin_unlock(&mm->page_table_lock);
3941         return 0;
3942 }
3943 #endif /* __PAGETABLE_PUD_FOLDED */
3944
3945 #ifndef __PAGETABLE_PMD_FOLDED
3946 /*
3947  * Allocate page middle directory.
3948  * We've already handled the fast-path in-line.
3949  */
3950 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3951 {
3952         spinlock_t *ptl;
3953         pmd_t *new = pmd_alloc_one(mm, address);
3954         if (!new)
3955                 return -ENOMEM;
3956
3957         smp_wmb(); /* See comment in __pte_alloc */
3958
3959         ptl = pud_lock(mm, pud);
3960 #ifndef __ARCH_HAS_4LEVEL_HACK
3961         if (!pud_present(*pud)) {
3962                 mm_inc_nr_pmds(mm);
3963                 pud_populate(mm, pud, new);
3964         } else  /* Another has populated it */
3965                 pmd_free(mm, new);
3966 #else
3967         if (!pgd_present(*pud)) {
3968                 mm_inc_nr_pmds(mm);
3969                 pgd_populate(mm, pud, new);
3970         } else /* Another has populated it */
3971                 pmd_free(mm, new);
3972 #endif /* __ARCH_HAS_4LEVEL_HACK */
3973         spin_unlock(ptl);
3974         return 0;
3975 }
3976 #endif /* __PAGETABLE_PMD_FOLDED */
3977
3978 static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
3979                 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
3980 {
3981         pgd_t *pgd;
3982         p4d_t *p4d;
3983         pud_t *pud;
3984         pmd_t *pmd;
3985         pte_t *ptep;
3986
3987         pgd = pgd_offset(mm, address);
3988         if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
3989                 goto out;
3990
3991         p4d = p4d_offset(pgd, address);
3992         if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
3993                 goto out;
3994
3995         pud = pud_offset(p4d, address);
3996         if (pud_none(*pud) || unlikely(pud_bad(*pud)))
3997                 goto out;
3998
3999         pmd = pmd_offset(pud, address);
4000         VM_BUG_ON(pmd_trans_huge(*pmd));
4001
4002         if (pmd_huge(*pmd)) {
4003                 if (!pmdpp)
4004                         goto out;
4005
4006                 *ptlp = pmd_lock(mm, pmd);
4007                 if (pmd_huge(*pmd)) {
4008                         *pmdpp = pmd;
4009                         return 0;
4010                 }
4011                 spin_unlock(*ptlp);
4012         }
4013
4014         if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
4015                 goto out;
4016
4017         ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
4018         if (!pte_present(*ptep))
4019                 goto unlock;
4020         *ptepp = ptep;
4021         return 0;
4022 unlock:
4023         pte_unmap_unlock(ptep, *ptlp);
4024 out:
4025         return -EINVAL;
4026 }
4027
4028 static inline int follow_pte(struct mm_struct *mm, unsigned long address,
4029                              pte_t **ptepp, spinlock_t **ptlp)
4030 {
4031         int res;
4032
4033         /* (void) is needed to make gcc happy */
4034         (void) __cond_lock(*ptlp,
4035                            !(res = __follow_pte_pmd(mm, address, ptepp, NULL,
4036                                            ptlp)));
4037         return res;
4038 }
4039
4040 int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4041                              pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4042 {
4043         int res;
4044
4045         /* (void) is needed to make gcc happy */
4046         (void) __cond_lock(*ptlp,
4047                            !(res = __follow_pte_pmd(mm, address, ptepp, pmdpp,
4048                                            ptlp)));
4049         return res;
4050 }
4051 EXPORT_SYMBOL(follow_pte_pmd);
4052
4053 /**
4054  * follow_pfn - look up PFN at a user virtual address
4055  * @vma: memory mapping
4056  * @address: user virtual address
4057  * @pfn: location to store found PFN
4058  *
4059  * Only IO mappings and raw PFN mappings are allowed.
4060  *
4061  * Returns zero and the pfn at @pfn on success, -ve otherwise.
4062  */
4063 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4064         unsigned long *pfn)
4065 {
4066         int ret = -EINVAL;
4067         spinlock_t *ptl;
4068         pte_t *ptep;
4069
4070         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4071                 return ret;
4072
4073         ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4074         if (ret)
4075                 return ret;
4076         *pfn = pte_pfn(*ptep);
4077         pte_unmap_unlock(ptep, ptl);
4078         return 0;
4079 }
4080 EXPORT_SYMBOL(follow_pfn);
4081
4082 #ifdef CONFIG_HAVE_IOREMAP_PROT
4083 int follow_phys(struct vm_area_struct *vma,
4084                 unsigned long address, unsigned int flags,
4085                 unsigned long *prot, resource_size_t *phys)
4086 {
4087         int ret = -EINVAL;
4088         pte_t *ptep, pte;
4089         spinlock_t *ptl;
4090
4091         if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4092                 goto out;
4093
4094         if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4095                 goto out;
4096         pte = *ptep;
4097
4098         if ((flags & FOLL_WRITE) && !pte_write(pte))
4099                 goto unlock;
4100
4101         *prot = pgprot_val(pte_pgprot(pte));
4102         *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4103
4104         ret = 0;
4105 unlock:
4106         pte_unmap_unlock(ptep, ptl);
4107 out:
4108         return ret;
4109 }
4110
4111 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4112                         void *buf, int len, int write)
4113 {
4114         resource_size_t phys_addr;
4115         unsigned long prot = 0;
4116         void __iomem *maddr;
4117         int offset = addr & (PAGE_SIZE-1);
4118
4119         if (follow_phys(vma, addr, write, &prot, &phys_addr))
4120                 return -EINVAL;
4121
4122         maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
4123         if (write)
4124                 memcpy_toio(maddr + offset, buf, len);
4125         else
4126                 memcpy_fromio(buf, maddr + offset, len);
4127         iounmap(maddr);
4128
4129         return len;
4130 }
4131 EXPORT_SYMBOL_GPL(generic_access_phys);
4132 #endif
4133
4134 /*
4135  * Access another process' address space as given in mm.  If non-NULL, use the
4136  * given task for page fault accounting.
4137  */
4138 int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
4139                 unsigned long addr, void *buf, int len, unsigned int gup_flags)
4140 {
4141         struct vm_area_struct *vma;
4142         void *old_buf = buf;
4143         int write = gup_flags & FOLL_WRITE;
4144
4145         down_read(&mm->mmap_sem);
4146         /* ignore errors, just check how much was successfully transferred */
4147         while (len) {
4148                 int bytes, ret, offset;
4149                 void *maddr;
4150                 struct page *page = NULL;
4151
4152                 ret = get_user_pages_remote(tsk, mm, addr, 1,
4153                                 gup_flags, &page, &vma, NULL);
4154                 if (ret <= 0) {
4155 #ifndef CONFIG_HAVE_IOREMAP_PROT
4156                         break;
4157 #else
4158                         /*
4159                          * Check if this is a VM_IO | VM_PFNMAP VMA, which
4160                          * we can access using slightly different code.
4161                          */
4162                         vma = find_vma(mm, addr);
4163                         if (!vma || vma->vm_start > addr)
4164                                 break;
4165                         if (vma->vm_ops && vma->vm_ops->access)
4166                                 ret = vma->vm_ops->access(vma, addr, buf,
4167                                                           len, write);
4168                         if (ret <= 0)
4169                                 break;
4170                         bytes = ret;
4171 #endif
4172                 } else {
4173                         bytes = len;
4174                         offset = addr & (PAGE_SIZE-1);
4175                         if (bytes > PAGE_SIZE-offset)
4176                                 bytes = PAGE_SIZE-offset;
4177
4178                         maddr = kmap(page);
4179                         if (write) {
4180                                 copy_to_user_page(vma, page, addr,
4181                                                   maddr + offset, buf, bytes);
4182                                 set_page_dirty_lock(page);
4183                         } else {
4184                                 copy_from_user_page(vma, page, addr,
4185                                                     buf, maddr + offset, bytes);
4186                         }
4187                         kunmap(page);
4188                         put_page(page);
4189                 }
4190                 len -= bytes;
4191                 buf += bytes;
4192                 addr += bytes;
4193         }
4194         up_read(&mm->mmap_sem);
4195
4196         return buf - old_buf;
4197 }
4198
4199 /**
4200  * access_remote_vm - access another process' address space
4201  * @mm:         the mm_struct of the target address space
4202  * @addr:       start address to access
4203  * @buf:        source or destination buffer
4204  * @len:        number of bytes to transfer
4205  * @gup_flags:  flags modifying lookup behaviour
4206  *
4207  * The caller must hold a reference on @mm.
4208  */
4209 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4210                 void *buf, int len, unsigned int gup_flags)
4211 {
4212         return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
4213 }
4214
4215 /*
4216  * Access another process' address space.
4217  * Source/target buffer must be kernel space,
4218  * Do not walk the page table directly, use get_user_pages
4219  */
4220 int access_process_vm(struct task_struct *tsk, unsigned long addr,
4221                 void *buf, int len, unsigned int gup_flags)
4222 {
4223         struct mm_struct *mm;
4224         int ret;
4225
4226         mm = get_task_mm(tsk);
4227         if (!mm)
4228                 return 0;
4229
4230         ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
4231
4232         mmput(mm);
4233
4234         return ret;
4235 }
4236 EXPORT_SYMBOL_GPL(access_process_vm);
4237
4238 /*
4239  * Print the name of a VMA.
4240  */
4241 void print_vma_addr(char *prefix, unsigned long ip)
4242 {
4243         struct mm_struct *mm = current->mm;
4244         struct vm_area_struct *vma;
4245
4246         /*
4247          * Do not print if we are in atomic
4248          * contexts (in exception stacks, etc.):
4249          */
4250         if (preempt_count())
4251                 return;
4252
4253         down_read(&mm->mmap_sem);
4254         vma = find_vma(mm, ip);
4255         if (vma && vma->vm_file) {
4256                 struct file *f = vma->vm_file;
4257                 char *buf = (char *)__get_free_page(GFP_KERNEL);
4258                 if (buf) {
4259                         char *p;
4260
4261                         p = file_path(f, buf, PAGE_SIZE);
4262                         if (IS_ERR(p))
4263                                 p = "?";
4264                         printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4265                                         vma->vm_start,
4266                                         vma->vm_end - vma->vm_start);
4267                         free_page((unsigned long)buf);
4268                 }
4269         }
4270         up_read(&mm->mmap_sem);
4271 }
4272
4273 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4274 void __might_fault(const char *file, int line)
4275 {
4276         /*
4277          * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4278          * holding the mmap_sem, this is safe because kernel memory doesn't
4279          * get paged out, therefore we'll never actually fault, and the
4280          * below annotations will generate false positives.
4281          */
4282         if (uaccess_kernel())
4283                 return;
4284         if (pagefault_disabled())
4285                 return;
4286         __might_sleep(file, line, 0);
4287 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4288         if (current->mm)
4289                 might_lock_read(&current->mm->mmap_sem);
4290 #endif
4291 }
4292 EXPORT_SYMBOL(__might_fault);
4293 #endif
4294
4295 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4296 static void clear_gigantic_page(struct page *page,
4297                                 unsigned long addr,
4298                                 unsigned int pages_per_huge_page)
4299 {
4300         int i;
4301         struct page *p = page;
4302
4303         might_sleep();
4304         for (i = 0; i < pages_per_huge_page;
4305              i++, p = mem_map_next(p, page, i)) {
4306                 cond_resched();
4307                 clear_user_highpage(p, addr + i * PAGE_SIZE);
4308         }
4309 }
4310 void clear_huge_page(struct page *page,
4311                      unsigned long addr, unsigned int pages_per_huge_page)
4312 {
4313         int i;
4314
4315         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4316                 clear_gigantic_page(page, addr, pages_per_huge_page);
4317                 return;
4318         }
4319
4320         might_sleep();
4321         for (i = 0; i < pages_per_huge_page; i++) {
4322                 cond_resched();
4323                 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4324         }
4325 }
4326
4327 static void copy_user_gigantic_page(struct page *dst, struct page *src,
4328                                     unsigned long addr,
4329                                     struct vm_area_struct *vma,
4330                                     unsigned int pages_per_huge_page)
4331 {
4332         int i;
4333         struct page *dst_base = dst;
4334         struct page *src_base = src;
4335
4336         for (i = 0; i < pages_per_huge_page; ) {
4337                 cond_resched();
4338                 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4339
4340                 i++;
4341                 dst = mem_map_next(dst, dst_base, i);
4342                 src = mem_map_next(src, src_base, i);
4343         }
4344 }
4345
4346 void copy_user_huge_page(struct page *dst, struct page *src,
4347                          unsigned long addr, struct vm_area_struct *vma,
4348                          unsigned int pages_per_huge_page)
4349 {
4350         int i;
4351
4352         if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4353                 copy_user_gigantic_page(dst, src, addr, vma,
4354                                         pages_per_huge_page);
4355                 return;
4356         }
4357
4358         might_sleep();
4359         for (i = 0; i < pages_per_huge_page; i++) {
4360                 cond_resched();
4361                 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
4362         }
4363 }
4364
4365 long copy_huge_page_from_user(struct page *dst_page,
4366                                 const void __user *usr_src,
4367                                 unsigned int pages_per_huge_page,
4368                                 bool allow_pagefault)
4369 {
4370         void *src = (void *)usr_src;
4371         void *page_kaddr;
4372         unsigned long i, rc = 0;
4373         unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
4374
4375         for (i = 0; i < pages_per_huge_page; i++) {
4376                 if (allow_pagefault)
4377                         page_kaddr = kmap(dst_page + i);
4378                 else
4379                         page_kaddr = kmap_atomic(dst_page + i);
4380                 rc = copy_from_user(page_kaddr,
4381                                 (const void __user *)(src + i * PAGE_SIZE),
4382                                 PAGE_SIZE);
4383                 if (allow_pagefault)
4384                         kunmap(dst_page + i);
4385                 else
4386                         kunmap_atomic(page_kaddr);
4387
4388                 ret_val -= (PAGE_SIZE - rc);
4389                 if (rc)
4390                         break;
4391
4392                 cond_resched();
4393         }
4394         return ret_val;
4395 }
4396 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4397
4398 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4399
4400 static struct kmem_cache *page_ptl_cachep;
4401
4402 void __init ptlock_cache_init(void)
4403 {
4404         page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
4405                         SLAB_PANIC, NULL);
4406 }
4407
4408 bool ptlock_alloc(struct page *page)
4409 {
4410         spinlock_t *ptl;
4411
4412         ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4413         if (!ptl)
4414                 return false;
4415         page->ptl = ptl;
4416         return true;
4417 }
4418
4419 void ptlock_free(struct page *page)
4420 {
4421         kmem_cache_free(page_ptl_cachep, page->ptl);
4422 }
4423 #endif