4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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
13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14 * pages started 02.12.91, seems to work. - Linus.
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
20 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
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.
32 * 05.04.94 - Multi-page memory management added for v1.1.
33 * Idea by Alex Bligh (alex@cconcepts.co.uk)
35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
36 * (Gerhard.Wichert@pdb.siemens.de)
38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
41 #include <linux/kernel_stat.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>
73 #include <asm/mmu_context.h>
74 #include <asm/pgalloc.h>
75 #include <linux/uaccess.h>
77 #include <asm/tlbflush.h>
78 #include <asm/pgtable.h>
82 #ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
83 #warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
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);
92 EXPORT_SYMBOL(mem_map);
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
103 EXPORT_SYMBOL(high_memory);
106 * Randomize the address space (stacks, mmaps, brk, etc.).
108 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
109 * as ancient (libc5 based) binaries can segfault. )
111 int randomize_va_space __read_mostly =
112 #ifdef CONFIG_COMPAT_BRK
118 static int __init disable_randmaps(char *s)
120 randomize_va_space = 0;
123 __setup("norandmaps", disable_randmaps);
125 unsigned long zero_pfn __read_mostly;
126 EXPORT_SYMBOL(zero_pfn);
128 unsigned long highest_memmap_pfn __read_mostly;
131 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
133 static int __init init_zero_pfn(void)
135 zero_pfn = page_to_pfn(ZERO_PAGE(0));
138 core_initcall(init_zero_pfn);
141 #if defined(SPLIT_RSS_COUNTING)
143 void sync_mm_rss(struct mm_struct *mm)
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;
153 current->rss_stat.events = 0;
156 static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
158 struct task_struct *task = current;
160 if (likely(task->mm == mm))
161 task->rss_stat.count[member] += val;
163 add_mm_counter(mm, member, val);
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)
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)
172 if (unlikely(task != current))
174 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
175 sync_mm_rss(task->mm);
177 #else /* SPLIT_RSS_COUNTING */
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)
182 static void check_sync_rss_stat(struct task_struct *task)
186 #endif /* SPLIT_RSS_COUNTING */
188 #ifdef HAVE_GENERIC_MMU_GATHER
190 static bool tlb_next_batch(struct mmu_gather *tlb)
192 struct mmu_gather_batch *batch;
196 tlb->active = batch->next;
200 if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
203 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
210 batch->max = MAX_GATHER_BATCH;
212 tlb->active->next = batch;
218 void arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
219 unsigned long start, unsigned long end)
223 /* Is it from 0 to ~0? */
224 tlb->fullmm = !(start | (end+1));
225 tlb->need_flush_all = 0;
226 tlb->local.next = NULL;
228 tlb->local.max = ARRAY_SIZE(tlb->__pages);
229 tlb->active = &tlb->local;
230 tlb->batch_count = 0;
232 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
237 __tlb_reset_range(tlb);
240 static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
246 mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
247 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
248 tlb_table_flush(tlb);
250 __tlb_reset_range(tlb);
253 static void tlb_flush_mmu_free(struct mmu_gather *tlb)
255 struct mmu_gather_batch *batch;
257 for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
258 free_pages_and_swap_cache(batch->pages, batch->nr);
261 tlb->active = &tlb->local;
264 void tlb_flush_mmu(struct mmu_gather *tlb)
266 tlb_flush_mmu_tlbonly(tlb);
267 tlb_flush_mmu_free(tlb);
271 * Called at the end of the shootdown operation to free up any resources
272 * that were required.
274 void arch_tlb_finish_mmu(struct mmu_gather *tlb,
275 unsigned long start, unsigned long end, bool force)
277 struct mmu_gather_batch *batch, *next;
280 __tlb_adjust_range(tlb, start, end - start);
284 /* keep the page table cache within bounds */
287 for (batch = tlb->local.next; batch; batch = next) {
289 free_pages((unsigned long)batch, 0);
291 tlb->local.next = NULL;
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.
301 bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size)
303 struct mmu_gather_batch *batch;
305 VM_BUG_ON(!tlb->end);
306 VM_WARN_ON(tlb->page_size != page_size);
310 * Add the page and check if we are full. If so
313 batch->pages[batch->nr++] = page;
314 if (batch->nr == batch->max) {
315 if (!tlb_next_batch(tlb))
319 VM_BUG_ON_PAGE(batch->nr > batch->max, page);
324 #endif /* HAVE_GENERIC_MMU_GATHER */
326 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
329 * See the comment near struct mmu_table_batch.
332 static void tlb_remove_table_smp_sync(void *arg)
334 /* Simply deliver the interrupt */
337 static void tlb_remove_table_one(void *table)
340 * This isn't an RCU grace period and hence the page-tables cannot be
341 * assumed to be actually RCU-freed.
343 * It is however sufficient for software page-table walkers that rely on
344 * IRQ disabling. See the comment near struct mmu_table_batch.
346 smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
347 __tlb_remove_table(table);
350 static void tlb_remove_table_rcu(struct rcu_head *head)
352 struct mmu_table_batch *batch;
355 batch = container_of(head, struct mmu_table_batch, rcu);
357 for (i = 0; i < batch->nr; i++)
358 __tlb_remove_table(batch->tables[i]);
360 free_page((unsigned long)batch);
363 void tlb_table_flush(struct mmu_gather *tlb)
365 struct mmu_table_batch **batch = &tlb->batch;
368 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
373 void tlb_remove_table(struct mmu_gather *tlb, void *table)
375 struct mmu_table_batch **batch = &tlb->batch;
378 * When there's less then two users of this mm there cannot be a
379 * concurrent page-table walk.
381 if (atomic_read(&tlb->mm->mm_users) < 2) {
382 __tlb_remove_table(table);
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);
394 (*batch)->tables[(*batch)->nr++] = table;
395 if ((*batch)->nr == MAX_TABLE_BATCH)
396 tlb_table_flush(tlb);
399 #endif /* CONFIG_HAVE_RCU_TABLE_FREE */
402 * Called to initialize an (on-stack) mmu_gather structure for page-table
403 * tear-down from @mm. The @fullmm argument is used when @mm is without
404 * users and we're going to destroy the full address space (exit/execve).
406 void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
407 unsigned long start, unsigned long end)
409 arch_tlb_gather_mmu(tlb, mm, start, end);
410 inc_tlb_flush_pending(tlb->mm);
413 void tlb_finish_mmu(struct mmu_gather *tlb,
414 unsigned long start, unsigned long end)
417 * If there are parallel threads are doing PTE changes on same range
418 * under non-exclusive lock(e.g., mmap_sem read-side) but defer TLB
419 * flush by batching, a thread has stable TLB entry can fail to flush
420 * the TLB by observing pte_none|!pte_dirty, for example so flush TLB
421 * forcefully if we detect parallel PTE batching threads.
423 bool force = mm_tlb_flush_nested(tlb->mm);
425 arch_tlb_finish_mmu(tlb, start, end, force);
426 dec_tlb_flush_pending(tlb->mm);
430 * Note: this doesn't free the actual pages themselves. That
431 * has been handled earlier when unmapping all the memory regions.
433 static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
436 pgtable_t token = pmd_pgtable(*pmd);
438 pte_free_tlb(tlb, token, addr);
439 atomic_long_dec(&tlb->mm->nr_ptes);
442 static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
443 unsigned long addr, unsigned long end,
444 unsigned long floor, unsigned long ceiling)
451 pmd = pmd_offset(pud, addr);
453 next = pmd_addr_end(addr, end);
454 if (pmd_none_or_clear_bad(pmd))
456 free_pte_range(tlb, pmd, addr);
457 } while (pmd++, addr = next, addr != end);
467 if (end - 1 > ceiling - 1)
470 pmd = pmd_offset(pud, start);
472 pmd_free_tlb(tlb, pmd, start);
473 mm_dec_nr_pmds(tlb->mm);
476 static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
477 unsigned long addr, unsigned long end,
478 unsigned long floor, unsigned long ceiling)
485 pud = pud_offset(p4d, addr);
487 next = pud_addr_end(addr, end);
488 if (pud_none_or_clear_bad(pud))
490 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
491 } while (pud++, addr = next, addr != end);
501 if (end - 1 > ceiling - 1)
504 pud = pud_offset(p4d, start);
506 pud_free_tlb(tlb, pud, start);
509 static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
510 unsigned long addr, unsigned long end,
511 unsigned long floor, unsigned long ceiling)
518 p4d = p4d_offset(pgd, addr);
520 next = p4d_addr_end(addr, end);
521 if (p4d_none_or_clear_bad(p4d))
523 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
524 } while (p4d++, addr = next, addr != end);
530 ceiling &= PGDIR_MASK;
534 if (end - 1 > ceiling - 1)
537 p4d = p4d_offset(pgd, start);
539 p4d_free_tlb(tlb, p4d, start);
543 * This function frees user-level page tables of a process.
545 void free_pgd_range(struct mmu_gather *tlb,
546 unsigned long addr, unsigned long end,
547 unsigned long floor, unsigned long ceiling)
553 * The next few lines have given us lots of grief...
555 * Why are we testing PMD* at this top level? Because often
556 * there will be no work to do at all, and we'd prefer not to
557 * go all the way down to the bottom just to discover that.
559 * Why all these "- 1"s? Because 0 represents both the bottom
560 * of the address space and the top of it (using -1 for the
561 * top wouldn't help much: the masks would do the wrong thing).
562 * The rule is that addr 0 and floor 0 refer to the bottom of
563 * the address space, but end 0 and ceiling 0 refer to the top
564 * Comparisons need to use "end - 1" and "ceiling - 1" (though
565 * that end 0 case should be mythical).
567 * Wherever addr is brought up or ceiling brought down, we must
568 * be careful to reject "the opposite 0" before it confuses the
569 * subsequent tests. But what about where end is brought down
570 * by PMD_SIZE below? no, end can't go down to 0 there.
572 * Whereas we round start (addr) and ceiling down, by different
573 * masks at different levels, in order to test whether a table
574 * now has no other vmas using it, so can be freed, we don't
575 * bother to round floor or end up - the tests don't need that.
589 if (end - 1 > ceiling - 1)
594 * We add page table cache pages with PAGE_SIZE,
595 * (see pte_free_tlb()), flush the tlb if we need
597 tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
598 pgd = pgd_offset(tlb->mm, addr);
600 next = pgd_addr_end(addr, end);
601 if (pgd_none_or_clear_bad(pgd))
603 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
604 } while (pgd++, addr = next, addr != end);
607 void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
608 unsigned long floor, unsigned long ceiling)
611 struct vm_area_struct *next = vma->vm_next;
612 unsigned long addr = vma->vm_start;
615 * Hide vma from rmap and truncate_pagecache before freeing
618 unlink_anon_vmas(vma);
619 unlink_file_vma(vma);
621 if (is_vm_hugetlb_page(vma)) {
622 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
623 floor, next ? next->vm_start : ceiling);
626 * Optimization: gather nearby vmas into one call down
628 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
629 && !is_vm_hugetlb_page(next)) {
632 unlink_anon_vmas(vma);
633 unlink_file_vma(vma);
635 free_pgd_range(tlb, addr, vma->vm_end,
636 floor, next ? next->vm_start : ceiling);
642 int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
645 pgtable_t new = pte_alloc_one(mm, address);
650 * Ensure all pte setup (eg. pte page lock and page clearing) are
651 * visible before the pte is made visible to other CPUs by being
652 * put into page tables.
654 * The other side of the story is the pointer chasing in the page
655 * table walking code (when walking the page table without locking;
656 * ie. most of the time). Fortunately, these data accesses consist
657 * of a chain of data-dependent loads, meaning most CPUs (alpha
658 * being the notable exception) will already guarantee loads are
659 * seen in-order. See the alpha page table accessors for the
660 * smp_read_barrier_depends() barriers in page table walking code.
662 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
664 ptl = pmd_lock(mm, pmd);
665 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
666 atomic_long_inc(&mm->nr_ptes);
667 pmd_populate(mm, pmd, new);
676 int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
678 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
682 smp_wmb(); /* See comment in __pte_alloc */
684 spin_lock(&init_mm.page_table_lock);
685 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
686 pmd_populate_kernel(&init_mm, pmd, new);
689 spin_unlock(&init_mm.page_table_lock);
691 pte_free_kernel(&init_mm, new);
695 static inline void init_rss_vec(int *rss)
697 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
700 static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
704 if (current->mm == mm)
706 for (i = 0; i < NR_MM_COUNTERS; i++)
708 add_mm_counter(mm, i, rss[i]);
712 * This function is called to print an error when a bad pte
713 * is found. For example, we might have a PFN-mapped pte in
714 * a region that doesn't allow it.
716 * The calling function must still handle the error.
718 static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
719 pte_t pte, struct page *page)
721 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
722 p4d_t *p4d = p4d_offset(pgd, addr);
723 pud_t *pud = pud_offset(p4d, addr);
724 pmd_t *pmd = pmd_offset(pud, addr);
725 struct address_space *mapping;
727 static unsigned long resume;
728 static unsigned long nr_shown;
729 static unsigned long nr_unshown;
732 * Allow a burst of 60 reports, then keep quiet for that minute;
733 * or allow a steady drip of one report per second.
735 if (nr_shown == 60) {
736 if (time_before(jiffies, resume)) {
741 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
748 resume = jiffies + 60 * HZ;
750 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
751 index = linear_page_index(vma, addr);
753 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
755 (long long)pte_val(pte), (long long)pmd_val(*pmd));
757 dump_page(page, "bad pte");
758 pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
759 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
761 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
763 pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
765 vma->vm_ops ? vma->vm_ops->fault : NULL,
766 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
767 mapping ? mapping->a_ops->readpage : NULL);
769 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
773 * vm_normal_page -- This function gets the "struct page" associated with a pte.
775 * "Special" mappings do not wish to be associated with a "struct page" (either
776 * it doesn't exist, or it exists but they don't want to touch it). In this
777 * case, NULL is returned here. "Normal" mappings do have a struct page.
779 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
780 * pte bit, in which case this function is trivial. Secondly, an architecture
781 * may not have a spare pte bit, which requires a more complicated scheme,
784 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
785 * special mapping (even if there are underlying and valid "struct pages").
786 * COWed pages of a VM_PFNMAP are always normal.
788 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
789 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
790 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
791 * mapping will always honor the rule
793 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
795 * And for normal mappings this is false.
797 * This restricts such mappings to be a linear translation from virtual address
798 * to pfn. To get around this restriction, we allow arbitrary mappings so long
799 * as the vma is not a COW mapping; in that case, we know that all ptes are
800 * special (because none can have been COWed).
803 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
805 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
806 * page" backing, however the difference is that _all_ pages with a struct
807 * page (that is, those where pfn_valid is true) are refcounted and considered
808 * normal pages by the VM. The disadvantage is that pages are refcounted
809 * (which can be slower and simply not an option for some PFNMAP users). The
810 * advantage is that we don't have to follow the strict linearity rule of
811 * PFNMAP mappings in order to support COWable mappings.
814 #ifdef __HAVE_ARCH_PTE_SPECIAL
815 # define HAVE_PTE_SPECIAL 1
817 # define HAVE_PTE_SPECIAL 0
819 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
822 unsigned long pfn = pte_pfn(pte);
824 if (HAVE_PTE_SPECIAL) {
825 if (likely(!pte_special(pte)))
827 if (vma->vm_ops && vma->vm_ops->find_special_page)
828 return vma->vm_ops->find_special_page(vma, addr);
829 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
831 if (!is_zero_pfn(pfn))
832 print_bad_pte(vma, addr, pte, NULL);
836 /* !HAVE_PTE_SPECIAL case follows: */
838 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
839 if (vma->vm_flags & VM_MIXEDMAP) {
845 off = (addr - vma->vm_start) >> PAGE_SHIFT;
846 if (pfn == vma->vm_pgoff + off)
848 if (!is_cow_mapping(vma->vm_flags))
853 if (is_zero_pfn(pfn))
856 if (unlikely(pfn > highest_memmap_pfn)) {
857 print_bad_pte(vma, addr, pte, NULL);
862 * NOTE! We still have PageReserved() pages in the page tables.
863 * eg. VDSO mappings can cause them to exist.
866 return pfn_to_page(pfn);
869 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
870 struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
873 unsigned long pfn = pmd_pfn(pmd);
876 * There is no pmd_special() but there may be special pmds, e.g.
877 * in a direct-access (dax) mapping, so let's just replicate the
878 * !HAVE_PTE_SPECIAL case from vm_normal_page() here.
880 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
881 if (vma->vm_flags & VM_MIXEDMAP) {
887 off = (addr - vma->vm_start) >> PAGE_SHIFT;
888 if (pfn == vma->vm_pgoff + off)
890 if (!is_cow_mapping(vma->vm_flags))
895 if (is_zero_pfn(pfn))
897 if (unlikely(pfn > highest_memmap_pfn))
901 * NOTE! We still have PageReserved() pages in the page tables.
902 * eg. VDSO mappings can cause them to exist.
905 return pfn_to_page(pfn);
910 * copy one vm_area from one task to the other. Assumes the page tables
911 * already present in the new task to be cleared in the whole range
912 * covered by this vma.
915 static inline unsigned long
916 copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
917 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
918 unsigned long addr, int *rss)
920 unsigned long vm_flags = vma->vm_flags;
921 pte_t pte = *src_pte;
924 /* pte contains position in swap or file, so copy. */
925 if (unlikely(!pte_present(pte))) {
926 swp_entry_t entry = pte_to_swp_entry(pte);
928 if (likely(!non_swap_entry(entry))) {
929 if (swap_duplicate(entry) < 0)
932 /* make sure dst_mm is on swapoff's mmlist. */
933 if (unlikely(list_empty(&dst_mm->mmlist))) {
934 spin_lock(&mmlist_lock);
935 if (list_empty(&dst_mm->mmlist))
936 list_add(&dst_mm->mmlist,
938 spin_unlock(&mmlist_lock);
941 } else if (is_migration_entry(entry)) {
942 page = migration_entry_to_page(entry);
944 rss[mm_counter(page)]++;
946 if (is_write_migration_entry(entry) &&
947 is_cow_mapping(vm_flags)) {
949 * COW mappings require pages in both
950 * parent and child to be set to read.
952 make_migration_entry_read(&entry);
953 pte = swp_entry_to_pte(entry);
954 if (pte_swp_soft_dirty(*src_pte))
955 pte = pte_swp_mksoft_dirty(pte);
956 set_pte_at(src_mm, addr, src_pte, pte);
963 * If it's a COW mapping, write protect it both
964 * in the parent and the child
966 if (is_cow_mapping(vm_flags)) {
967 ptep_set_wrprotect(src_mm, addr, src_pte);
968 pte = pte_wrprotect(pte);
972 * If it's a shared mapping, mark it clean in
975 if (vm_flags & VM_SHARED)
976 pte = pte_mkclean(pte);
977 pte = pte_mkold(pte);
979 page = vm_normal_page(vma, addr, pte);
982 page_dup_rmap(page, false);
983 rss[mm_counter(page)]++;
987 set_pte_at(dst_mm, addr, dst_pte, pte);
991 static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
992 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
993 unsigned long addr, unsigned long end)
995 pte_t *orig_src_pte, *orig_dst_pte;
996 pte_t *src_pte, *dst_pte;
997 spinlock_t *src_ptl, *dst_ptl;
999 int rss[NR_MM_COUNTERS];
1000 swp_entry_t entry = (swp_entry_t){0};
1005 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
1008 src_pte = pte_offset_map(src_pmd, addr);
1009 src_ptl = pte_lockptr(src_mm, src_pmd);
1010 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1011 orig_src_pte = src_pte;
1012 orig_dst_pte = dst_pte;
1013 arch_enter_lazy_mmu_mode();
1017 * We are holding two locks at this point - either of them
1018 * could generate latencies in another task on another CPU.
1020 if (progress >= 32) {
1022 if (need_resched() ||
1023 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1026 if (pte_none(*src_pte)) {
1030 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
1035 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
1037 arch_leave_lazy_mmu_mode();
1038 spin_unlock(src_ptl);
1039 pte_unmap(orig_src_pte);
1040 add_mm_rss_vec(dst_mm, rss);
1041 pte_unmap_unlock(orig_dst_pte, dst_ptl);
1045 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
1054 static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1055 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
1056 unsigned long addr, unsigned long end)
1058 pmd_t *src_pmd, *dst_pmd;
1061 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1064 src_pmd = pmd_offset(src_pud, addr);
1066 next = pmd_addr_end(addr, end);
1067 if (pmd_trans_huge(*src_pmd) || pmd_devmap(*src_pmd)) {
1069 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
1070 err = copy_huge_pmd(dst_mm, src_mm,
1071 dst_pmd, src_pmd, addr, vma);
1078 if (pmd_none_or_clear_bad(src_pmd))
1080 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1083 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1087 static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1088 p4d_t *dst_p4d, p4d_t *src_p4d, struct vm_area_struct *vma,
1089 unsigned long addr, unsigned long end)
1091 pud_t *src_pud, *dst_pud;
1094 dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1097 src_pud = pud_offset(src_p4d, addr);
1099 next = pud_addr_end(addr, end);
1100 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1103 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma);
1104 err = copy_huge_pud(dst_mm, src_mm,
1105 dst_pud, src_pud, addr, vma);
1112 if (pud_none_or_clear_bad(src_pud))
1114 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1117 } while (dst_pud++, src_pud++, addr = next, addr != end);
1121 static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1122 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1123 unsigned long addr, unsigned long end)
1125 p4d_t *src_p4d, *dst_p4d;
1128 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1131 src_p4d = p4d_offset(src_pgd, addr);
1133 next = p4d_addr_end(addr, end);
1134 if (p4d_none_or_clear_bad(src_p4d))
1136 if (copy_pud_range(dst_mm, src_mm, dst_p4d, src_p4d,
1139 } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1143 int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1144 struct vm_area_struct *vma)
1146 pgd_t *src_pgd, *dst_pgd;
1148 unsigned long addr = vma->vm_start;
1149 unsigned long end = vma->vm_end;
1150 unsigned long mmun_start; /* For mmu_notifiers */
1151 unsigned long mmun_end; /* For mmu_notifiers */
1156 * Don't copy ptes where a page fault will fill them correctly.
1157 * Fork becomes much lighter when there are big shared or private
1158 * readonly mappings. The tradeoff is that copy_page_range is more
1159 * efficient than faulting.
1161 if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
1165 if (is_vm_hugetlb_page(vma))
1166 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1168 if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1170 * We do not free on error cases below as remove_vma
1171 * gets called on error from higher level routine
1173 ret = track_pfn_copy(vma);
1179 * We need to invalidate the secondary MMU mappings only when
1180 * there could be a permission downgrade on the ptes of the
1181 * parent mm. And a permission downgrade will only happen if
1182 * is_cow_mapping() returns true.
1184 is_cow = is_cow_mapping(vma->vm_flags);
1188 mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1192 dst_pgd = pgd_offset(dst_mm, addr);
1193 src_pgd = pgd_offset(src_mm, addr);
1195 next = pgd_addr_end(addr, end);
1196 if (pgd_none_or_clear_bad(src_pgd))
1198 if (unlikely(copy_p4d_range(dst_mm, src_mm, dst_pgd, src_pgd,
1199 vma, addr, next))) {
1203 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1206 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1210 static unsigned long zap_pte_range(struct mmu_gather *tlb,
1211 struct vm_area_struct *vma, pmd_t *pmd,
1212 unsigned long addr, unsigned long end,
1213 struct zap_details *details)
1215 struct mm_struct *mm = tlb->mm;
1216 int force_flush = 0;
1217 int rss[NR_MM_COUNTERS];
1223 tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
1226 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1228 flush_tlb_batched_pending(mm);
1229 arch_enter_lazy_mmu_mode();
1232 if (pte_none(ptent))
1235 if (pte_present(ptent)) {
1238 page = vm_normal_page(vma, addr, ptent);
1239 if (unlikely(details) && page) {
1241 * unmap_shared_mapping_pages() wants to
1242 * invalidate cache without truncating:
1243 * unmap shared but keep private pages.
1245 if (details->check_mapping &&
1246 details->check_mapping != page_rmapping(page))
1249 ptent = ptep_get_and_clear_full(mm, addr, pte,
1251 tlb_remove_tlb_entry(tlb, pte, addr);
1252 if (unlikely(!page))
1255 if (!PageAnon(page)) {
1256 if (pte_dirty(ptent)) {
1258 set_page_dirty(page);
1260 if (pte_young(ptent) &&
1261 likely(!(vma->vm_flags & VM_SEQ_READ)))
1262 mark_page_accessed(page);
1264 rss[mm_counter(page)]--;
1265 page_remove_rmap(page, false);
1266 if (unlikely(page_mapcount(page) < 0))
1267 print_bad_pte(vma, addr, ptent, page);
1268 if (unlikely(__tlb_remove_page(tlb, page))) {
1275 /* If details->check_mapping, we leave swap entries. */
1276 if (unlikely(details))
1279 entry = pte_to_swp_entry(ptent);
1280 if (!non_swap_entry(entry))
1282 else if (is_migration_entry(entry)) {
1285 page = migration_entry_to_page(entry);
1286 rss[mm_counter(page)]--;
1288 if (unlikely(!free_swap_and_cache(entry)))
1289 print_bad_pte(vma, addr, ptent, NULL);
1290 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1291 } while (pte++, addr += PAGE_SIZE, addr != end);
1293 add_mm_rss_vec(mm, rss);
1294 arch_leave_lazy_mmu_mode();
1296 /* Do the actual TLB flush before dropping ptl */
1298 tlb_flush_mmu_tlbonly(tlb);
1299 pte_unmap_unlock(start_pte, ptl);
1302 * If we forced a TLB flush (either due to running out of
1303 * batch buffers or because we needed to flush dirty TLB
1304 * entries before releasing the ptl), free the batched
1305 * memory too. Restart if we didn't do everything.
1309 tlb_flush_mmu_free(tlb);
1317 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1318 struct vm_area_struct *vma, pud_t *pud,
1319 unsigned long addr, unsigned long end,
1320 struct zap_details *details)
1325 pmd = pmd_offset(pud, addr);
1327 next = pmd_addr_end(addr, end);
1328 if (pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1329 if (next - addr != HPAGE_PMD_SIZE) {
1330 VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
1331 !rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1332 __split_huge_pmd(vma, pmd, addr, false, NULL);
1333 } else if (zap_huge_pmd(tlb, vma, pmd, addr))
1338 * Here there can be other concurrent MADV_DONTNEED or
1339 * trans huge page faults running, and if the pmd is
1340 * none or trans huge it can change under us. This is
1341 * because MADV_DONTNEED holds the mmap_sem in read
1344 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1346 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1349 } while (pmd++, addr = next, addr != end);
1354 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1355 struct vm_area_struct *vma, p4d_t *p4d,
1356 unsigned long addr, unsigned long end,
1357 struct zap_details *details)
1362 pud = pud_offset(p4d, addr);
1364 next = pud_addr_end(addr, end);
1365 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1366 if (next - addr != HPAGE_PUD_SIZE) {
1367 VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1368 split_huge_pud(vma, pud, addr);
1369 } else if (zap_huge_pud(tlb, vma, pud, addr))
1373 if (pud_none_or_clear_bad(pud))
1375 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1378 } while (pud++, addr = next, addr != end);
1383 static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1384 struct vm_area_struct *vma, pgd_t *pgd,
1385 unsigned long addr, unsigned long end,
1386 struct zap_details *details)
1391 p4d = p4d_offset(pgd, addr);
1393 next = p4d_addr_end(addr, end);
1394 if (p4d_none_or_clear_bad(p4d))
1396 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1397 } while (p4d++, addr = next, addr != end);
1402 void unmap_page_range(struct mmu_gather *tlb,
1403 struct vm_area_struct *vma,
1404 unsigned long addr, unsigned long end,
1405 struct zap_details *details)
1410 BUG_ON(addr >= end);
1411 tlb_start_vma(tlb, vma);
1412 pgd = pgd_offset(vma->vm_mm, addr);
1414 next = pgd_addr_end(addr, end);
1415 if (pgd_none_or_clear_bad(pgd))
1417 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1418 } while (pgd++, addr = next, addr != end);
1419 tlb_end_vma(tlb, vma);
1423 static void unmap_single_vma(struct mmu_gather *tlb,
1424 struct vm_area_struct *vma, unsigned long start_addr,
1425 unsigned long end_addr,
1426 struct zap_details *details)
1428 unsigned long start = max(vma->vm_start, start_addr);
1431 if (start >= vma->vm_end)
1433 end = min(vma->vm_end, end_addr);
1434 if (end <= vma->vm_start)
1438 uprobe_munmap(vma, start, end);
1440 if (unlikely(vma->vm_flags & VM_PFNMAP))
1441 untrack_pfn(vma, 0, 0);
1444 if (unlikely(is_vm_hugetlb_page(vma))) {
1446 * It is undesirable to test vma->vm_file as it
1447 * should be non-null for valid hugetlb area.
1448 * However, vm_file will be NULL in the error
1449 * cleanup path of mmap_region. When
1450 * hugetlbfs ->mmap method fails,
1451 * mmap_region() nullifies vma->vm_file
1452 * before calling this function to clean up.
1453 * Since no pte has actually been setup, it is
1454 * safe to do nothing in this case.
1457 i_mmap_lock_write(vma->vm_file->f_mapping);
1458 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1459 i_mmap_unlock_write(vma->vm_file->f_mapping);
1462 unmap_page_range(tlb, vma, start, end, details);
1467 * unmap_vmas - unmap a range of memory covered by a list of vma's
1468 * @tlb: address of the caller's struct mmu_gather
1469 * @vma: the starting vma
1470 * @start_addr: virtual address at which to start unmapping
1471 * @end_addr: virtual address at which to end unmapping
1473 * Unmap all pages in the vma list.
1475 * Only addresses between `start' and `end' will be unmapped.
1477 * The VMA list must be sorted in ascending virtual address order.
1479 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1480 * range after unmap_vmas() returns. So the only responsibility here is to
1481 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1482 * drops the lock and schedules.
1484 void unmap_vmas(struct mmu_gather *tlb,
1485 struct vm_area_struct *vma, unsigned long start_addr,
1486 unsigned long end_addr)
1488 struct mm_struct *mm = vma->vm_mm;
1490 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1491 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1492 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1493 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1497 * zap_page_range - remove user pages in a given range
1498 * @vma: vm_area_struct holding the applicable pages
1499 * @start: starting address of pages to zap
1500 * @size: number of bytes to zap
1502 * Caller must protect the VMA list
1504 void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1507 struct mm_struct *mm = vma->vm_mm;
1508 struct mmu_gather tlb;
1509 unsigned long end = start + size;
1512 tlb_gather_mmu(&tlb, mm, start, end);
1513 update_hiwater_rss(mm);
1514 mmu_notifier_invalidate_range_start(mm, start, end);
1515 for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1516 unmap_single_vma(&tlb, vma, start, end, NULL);
1517 mmu_notifier_invalidate_range_end(mm, start, end);
1518 tlb_finish_mmu(&tlb, start, end);
1522 * zap_page_range_single - remove user pages in a given range
1523 * @vma: vm_area_struct holding the applicable pages
1524 * @address: starting address of pages to zap
1525 * @size: number of bytes to zap
1526 * @details: details of shared cache invalidation
1528 * The range must fit into one VMA.
1530 static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1531 unsigned long size, struct zap_details *details)
1533 struct mm_struct *mm = vma->vm_mm;
1534 struct mmu_gather tlb;
1535 unsigned long end = address + size;
1538 tlb_gather_mmu(&tlb, mm, address, end);
1539 update_hiwater_rss(mm);
1540 mmu_notifier_invalidate_range_start(mm, address, end);
1541 unmap_single_vma(&tlb, vma, address, end, details);
1542 mmu_notifier_invalidate_range_end(mm, address, end);
1543 tlb_finish_mmu(&tlb, address, end);
1547 * zap_vma_ptes - remove ptes mapping the vma
1548 * @vma: vm_area_struct holding ptes to be zapped
1549 * @address: starting address of pages to zap
1550 * @size: number of bytes to zap
1552 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1554 * The entire address range must be fully contained within the vma.
1556 * Returns 0 if successful.
1558 int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1561 if (address < vma->vm_start || address + size > vma->vm_end ||
1562 !(vma->vm_flags & VM_PFNMAP))
1564 zap_page_range_single(vma, address, size, NULL);
1567 EXPORT_SYMBOL_GPL(zap_vma_ptes);
1569 pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1577 pgd = pgd_offset(mm, addr);
1578 p4d = p4d_alloc(mm, pgd, addr);
1581 pud = pud_alloc(mm, p4d, addr);
1584 pmd = pmd_alloc(mm, pud, addr);
1588 VM_BUG_ON(pmd_trans_huge(*pmd));
1589 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1593 * This is the old fallback for page remapping.
1595 * For historical reasons, it only allows reserved pages. Only
1596 * old drivers should use this, and they needed to mark their
1597 * pages reserved for the old functions anyway.
1599 static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1600 struct page *page, pgprot_t prot)
1602 struct mm_struct *mm = vma->vm_mm;
1611 flush_dcache_page(page);
1612 pte = get_locked_pte(mm, addr, &ptl);
1616 if (!pte_none(*pte))
1619 /* Ok, finally just insert the thing.. */
1621 inc_mm_counter_fast(mm, mm_counter_file(page));
1622 page_add_file_rmap(page, false);
1623 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1626 pte_unmap_unlock(pte, ptl);
1629 pte_unmap_unlock(pte, ptl);
1635 * vm_insert_page - insert single page into user vma
1636 * @vma: user vma to map to
1637 * @addr: target user address of this page
1638 * @page: source kernel page
1640 * This allows drivers to insert individual pages they've allocated
1643 * The page has to be a nice clean _individual_ kernel allocation.
1644 * If you allocate a compound page, you need to have marked it as
1645 * such (__GFP_COMP), or manually just split the page up yourself
1646 * (see split_page()).
1648 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1649 * took an arbitrary page protection parameter. This doesn't allow
1650 * that. Your vma protection will have to be set up correctly, which
1651 * means that if you want a shared writable mapping, you'd better
1652 * ask for a shared writable mapping!
1654 * The page does not need to be reserved.
1656 * Usually this function is called from f_op->mmap() handler
1657 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1658 * Caller must set VM_MIXEDMAP on vma if it wants to call this
1659 * function from other places, for example from page-fault handler.
1661 int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1664 if (addr < vma->vm_start || addr >= vma->vm_end)
1666 if (!page_count(page))
1668 if (!(vma->vm_flags & VM_MIXEDMAP)) {
1669 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1670 BUG_ON(vma->vm_flags & VM_PFNMAP);
1671 vma->vm_flags |= VM_MIXEDMAP;
1673 return insert_page(vma, addr, page, vma->vm_page_prot);
1675 EXPORT_SYMBOL(vm_insert_page);
1677 static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1678 pfn_t pfn, pgprot_t prot)
1680 struct mm_struct *mm = vma->vm_mm;
1686 pte = get_locked_pte(mm, addr, &ptl);
1690 if (!pte_none(*pte))
1693 /* Ok, finally just insert the thing.. */
1694 if (pfn_t_devmap(pfn))
1695 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
1697 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
1698 set_pte_at(mm, addr, pte, entry);
1699 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1703 pte_unmap_unlock(pte, ptl);
1709 * vm_insert_pfn - insert single pfn into user vma
1710 * @vma: user vma to map to
1711 * @addr: target user address of this page
1712 * @pfn: source kernel pfn
1714 * Similar to vm_insert_page, this allows drivers to insert individual pages
1715 * they've allocated into a user vma. Same comments apply.
1717 * This function should only be called from a vm_ops->fault handler, and
1718 * in that case the handler should return NULL.
1720 * vma cannot be a COW mapping.
1722 * As this is called only for pages that do not currently exist, we
1723 * do not need to flush old virtual caches or the TLB.
1725 int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1728 return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
1730 EXPORT_SYMBOL(vm_insert_pfn);
1733 * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1734 * @vma: user vma to map to
1735 * @addr: target user address of this page
1736 * @pfn: source kernel pfn
1737 * @pgprot: pgprot flags for the inserted page
1739 * This is exactly like vm_insert_pfn, except that it allows drivers to
1740 * to override pgprot on a per-page basis.
1742 * This only makes sense for IO mappings, and it makes no sense for
1743 * cow mappings. In general, using multiple vmas is preferable;
1744 * vm_insert_pfn_prot should only be used if using multiple VMAs is
1747 int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
1748 unsigned long pfn, pgprot_t pgprot)
1752 * Technically, architectures with pte_special can avoid all these
1753 * restrictions (same for remap_pfn_range). However we would like
1754 * consistency in testing and feature parity among all, so we should
1755 * try to keep these invariants in place for everybody.
1757 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1758 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1759 (VM_PFNMAP|VM_MIXEDMAP));
1760 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1761 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1763 if (addr < vma->vm_start || addr >= vma->vm_end)
1766 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
1768 ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot);
1772 EXPORT_SYMBOL(vm_insert_pfn_prot);
1774 int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1777 pgprot_t pgprot = vma->vm_page_prot;
1779 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
1781 if (addr < vma->vm_start || addr >= vma->vm_end)
1784 track_pfn_insert(vma, &pgprot, pfn);
1787 * If we don't have pte special, then we have to use the pfn_valid()
1788 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1789 * refcount the page if pfn_valid is true (hence insert_page rather
1790 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1791 * without pte special, it would there be refcounted as a normal page.
1793 if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
1797 * At this point we are committed to insert_page()
1798 * regardless of whether the caller specified flags that
1799 * result in pfn_t_has_page() == false.
1801 page = pfn_to_page(pfn_t_to_pfn(pfn));
1802 return insert_page(vma, addr, page, pgprot);
1804 return insert_pfn(vma, addr, pfn, pgprot);
1806 EXPORT_SYMBOL(vm_insert_mixed);
1809 * maps a range of physical memory into the requested pages. the old
1810 * mappings are removed. any references to nonexistent pages results
1811 * in null mappings (currently treated as "copy-on-access")
1813 static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1814 unsigned long addr, unsigned long end,
1815 unsigned long pfn, pgprot_t prot)
1820 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1823 arch_enter_lazy_mmu_mode();
1825 BUG_ON(!pte_none(*pte));
1826 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1828 } while (pte++, addr += PAGE_SIZE, addr != end);
1829 arch_leave_lazy_mmu_mode();
1830 pte_unmap_unlock(pte - 1, ptl);
1834 static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1835 unsigned long addr, unsigned long end,
1836 unsigned long pfn, pgprot_t prot)
1841 pfn -= addr >> PAGE_SHIFT;
1842 pmd = pmd_alloc(mm, pud, addr);
1845 VM_BUG_ON(pmd_trans_huge(*pmd));
1847 next = pmd_addr_end(addr, end);
1848 if (remap_pte_range(mm, pmd, addr, next,
1849 pfn + (addr >> PAGE_SHIFT), prot))
1851 } while (pmd++, addr = next, addr != end);
1855 static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
1856 unsigned long addr, unsigned long end,
1857 unsigned long pfn, pgprot_t prot)
1862 pfn -= addr >> PAGE_SHIFT;
1863 pud = pud_alloc(mm, p4d, addr);
1867 next = pud_addr_end(addr, end);
1868 if (remap_pmd_range(mm, pud, addr, next,
1869 pfn + (addr >> PAGE_SHIFT), prot))
1871 } while (pud++, addr = next, addr != end);
1875 static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
1876 unsigned long addr, unsigned long end,
1877 unsigned long pfn, pgprot_t prot)
1882 pfn -= addr >> PAGE_SHIFT;
1883 p4d = p4d_alloc(mm, pgd, addr);
1887 next = p4d_addr_end(addr, end);
1888 if (remap_pud_range(mm, p4d, addr, next,
1889 pfn + (addr >> PAGE_SHIFT), prot))
1891 } while (p4d++, addr = next, addr != end);
1896 * remap_pfn_range - remap kernel memory to userspace
1897 * @vma: user vma to map to
1898 * @addr: target user address to start at
1899 * @pfn: physical address of kernel memory
1900 * @size: size of map area
1901 * @prot: page protection flags for this mapping
1903 * Note: this is only safe if the mm semaphore is held when called.
1905 int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
1906 unsigned long pfn, unsigned long size, pgprot_t prot)
1910 unsigned long end = addr + PAGE_ALIGN(size);
1911 struct mm_struct *mm = vma->vm_mm;
1912 unsigned long remap_pfn = pfn;
1916 * Physically remapped pages are special. Tell the
1917 * rest of the world about it:
1918 * VM_IO tells people not to look at these pages
1919 * (accesses can have side effects).
1920 * VM_PFNMAP tells the core MM that the base pages are just
1921 * raw PFN mappings, and do not have a "struct page" associated
1924 * Disable vma merging and expanding with mremap().
1926 * Omit vma from core dump, even when VM_IO turned off.
1928 * There's a horrible special case to handle copy-on-write
1929 * behaviour that some programs depend on. We mark the "original"
1930 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
1931 * See vm_normal_page() for details.
1933 if (is_cow_mapping(vma->vm_flags)) {
1934 if (addr != vma->vm_start || end != vma->vm_end)
1936 vma->vm_pgoff = pfn;
1939 err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
1943 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
1945 BUG_ON(addr >= end);
1946 pfn -= addr >> PAGE_SHIFT;
1947 pgd = pgd_offset(mm, addr);
1948 flush_cache_range(vma, addr, end);
1950 next = pgd_addr_end(addr, end);
1951 err = remap_p4d_range(mm, pgd, addr, next,
1952 pfn + (addr >> PAGE_SHIFT), prot);
1955 } while (pgd++, addr = next, addr != end);
1958 untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
1962 EXPORT_SYMBOL(remap_pfn_range);
1965 * vm_iomap_memory - remap memory to userspace
1966 * @vma: user vma to map to
1967 * @start: start of area
1968 * @len: size of area
1970 * This is a simplified io_remap_pfn_range() for common driver use. The
1971 * driver just needs to give us the physical memory range to be mapped,
1972 * we'll figure out the rest from the vma information.
1974 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
1975 * whatever write-combining details or similar.
1977 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
1979 unsigned long vm_len, pfn, pages;
1981 /* Check that the physical memory area passed in looks valid */
1982 if (start + len < start)
1985 * You *really* shouldn't map things that aren't page-aligned,
1986 * but we've historically allowed it because IO memory might
1987 * just have smaller alignment.
1989 len += start & ~PAGE_MASK;
1990 pfn = start >> PAGE_SHIFT;
1991 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
1992 if (pfn + pages < pfn)
1995 /* We start the mapping 'vm_pgoff' pages into the area */
1996 if (vma->vm_pgoff > pages)
1998 pfn += vma->vm_pgoff;
1999 pages -= vma->vm_pgoff;
2001 /* Can we fit all of the mapping? */
2002 vm_len = vma->vm_end - vma->vm_start;
2003 if (vm_len >> PAGE_SHIFT > pages)
2006 /* Ok, let it rip */
2007 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2009 EXPORT_SYMBOL(vm_iomap_memory);
2011 static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2012 unsigned long addr, unsigned long end,
2013 pte_fn_t fn, void *data)
2018 spinlock_t *uninitialized_var(ptl);
2020 pte = (mm == &init_mm) ?
2021 pte_alloc_kernel(pmd, addr) :
2022 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2026 BUG_ON(pmd_huge(*pmd));
2028 arch_enter_lazy_mmu_mode();
2030 token = pmd_pgtable(*pmd);
2033 err = fn(pte++, token, addr, data);
2036 } while (addr += PAGE_SIZE, addr != end);
2038 arch_leave_lazy_mmu_mode();
2041 pte_unmap_unlock(pte-1, ptl);
2045 static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2046 unsigned long addr, unsigned long end,
2047 pte_fn_t fn, void *data)
2053 BUG_ON(pud_huge(*pud));
2055 pmd = pmd_alloc(mm, pud, addr);
2059 next = pmd_addr_end(addr, end);
2060 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2063 } while (pmd++, addr = next, addr != end);
2067 static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2068 unsigned long addr, unsigned long end,
2069 pte_fn_t fn, void *data)
2075 pud = pud_alloc(mm, p4d, addr);
2079 next = pud_addr_end(addr, end);
2080 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2083 } while (pud++, addr = next, addr != end);
2087 static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2088 unsigned long addr, unsigned long end,
2089 pte_fn_t fn, void *data)
2095 p4d = p4d_alloc(mm, pgd, addr);
2099 next = p4d_addr_end(addr, end);
2100 err = apply_to_pud_range(mm, p4d, addr, next, fn, data);
2103 } while (p4d++, addr = next, addr != end);
2108 * Scan a region of virtual memory, filling in page tables as necessary
2109 * and calling a provided function on each leaf page table.
2111 int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2112 unsigned long size, pte_fn_t fn, void *data)
2116 unsigned long end = addr + size;
2119 if (WARN_ON(addr >= end))
2122 pgd = pgd_offset(mm, addr);
2124 next = pgd_addr_end(addr, end);
2125 err = apply_to_p4d_range(mm, pgd, addr, next, fn, data);
2128 } while (pgd++, addr = next, addr != end);
2132 EXPORT_SYMBOL_GPL(apply_to_page_range);
2135 * handle_pte_fault chooses page fault handler according to an entry which was
2136 * read non-atomically. Before making any commitment, on those architectures
2137 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2138 * parts, do_swap_page must check under lock before unmapping the pte and
2139 * proceeding (but do_wp_page is only called after already making such a check;
2140 * and do_anonymous_page can safely check later on).
2142 static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2143 pte_t *page_table, pte_t orig_pte)
2146 #if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2147 if (sizeof(pte_t) > sizeof(unsigned long)) {
2148 spinlock_t *ptl = pte_lockptr(mm, pmd);
2150 same = pte_same(*page_table, orig_pte);
2154 pte_unmap(page_table);
2158 static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2160 debug_dma_assert_idle(src);
2163 * If the source page was a PFN mapping, we don't have
2164 * a "struct page" for it. We do a best-effort copy by
2165 * just copying from the original user address. If that
2166 * fails, we just zero-fill it. Live with it.
2168 if (unlikely(!src)) {
2169 void *kaddr = kmap_atomic(dst);
2170 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2173 * This really shouldn't fail, because the page is there
2174 * in the page tables. But it might just be unreadable,
2175 * in which case we just give up and fill the result with
2178 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2180 kunmap_atomic(kaddr);
2181 flush_dcache_page(dst);
2183 copy_user_highpage(dst, src, va, vma);
2186 static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2188 struct file *vm_file = vma->vm_file;
2191 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2194 * Special mappings (e.g. VDSO) do not have any file so fake
2195 * a default GFP_KERNEL for them.
2201 * Notify the address space that the page is about to become writable so that
2202 * it can prohibit this or wait for the page to get into an appropriate state.
2204 * We do this without the lock held, so that it can sleep if it needs to.
2206 static int do_page_mkwrite(struct vm_fault *vmf)
2209 struct page *page = vmf->page;
2210 unsigned int old_flags = vmf->flags;
2212 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2214 ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2215 /* Restore original flags so that caller is not surprised */
2216 vmf->flags = old_flags;
2217 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2219 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2221 if (!page->mapping) {
2223 return 0; /* retry */
2225 ret |= VM_FAULT_LOCKED;
2227 VM_BUG_ON_PAGE(!PageLocked(page), page);
2232 * Handle dirtying of a page in shared file mapping on a write fault.
2234 * The function expects the page to be locked and unlocks it.
2236 static void fault_dirty_shared_page(struct vm_area_struct *vma,
2239 struct address_space *mapping;
2241 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2243 dirtied = set_page_dirty(page);
2244 VM_BUG_ON_PAGE(PageAnon(page), page);
2246 * Take a local copy of the address_space - page.mapping may be zeroed
2247 * by truncate after unlock_page(). The address_space itself remains
2248 * pinned by vma->vm_file's reference. We rely on unlock_page()'s
2249 * release semantics to prevent the compiler from undoing this copying.
2251 mapping = page_rmapping(page);
2254 if ((dirtied || page_mkwrite) && mapping) {
2256 * Some device drivers do not set page.mapping
2257 * but still dirty their pages
2259 balance_dirty_pages_ratelimited(mapping);
2263 file_update_time(vma->vm_file);
2267 * Handle write page faults for pages that can be reused in the current vma
2269 * This can happen either due to the mapping being with the VM_SHARED flag,
2270 * or due to us being the last reference standing to the page. In either
2271 * case, all we need to do here is to mark the page as writable and update
2272 * any related book-keeping.
2274 static inline void wp_page_reuse(struct vm_fault *vmf)
2275 __releases(vmf->ptl)
2277 struct vm_area_struct *vma = vmf->vma;
2278 struct page *page = vmf->page;
2281 * Clear the pages cpupid information as the existing
2282 * information potentially belongs to a now completely
2283 * unrelated process.
2286 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2288 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2289 entry = pte_mkyoung(vmf->orig_pte);
2290 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2291 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
2292 update_mmu_cache(vma, vmf->address, vmf->pte);
2293 pte_unmap_unlock(vmf->pte, vmf->ptl);
2297 * Handle the case of a page which we actually need to copy to a new page.
2299 * Called with mmap_sem locked and the old page referenced, but
2300 * without the ptl held.
2302 * High level logic flow:
2304 * - Allocate a page, copy the content of the old page to the new one.
2305 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2306 * - Take the PTL. If the pte changed, bail out and release the allocated page
2307 * - If the pte is still the way we remember it, update the page table and all
2308 * relevant references. This includes dropping the reference the page-table
2309 * held to the old page, as well as updating the rmap.
2310 * - In any case, unlock the PTL and drop the reference we took to the old page.
2312 static int wp_page_copy(struct vm_fault *vmf)
2314 struct vm_area_struct *vma = vmf->vma;
2315 struct mm_struct *mm = vma->vm_mm;
2316 struct page *old_page = vmf->page;
2317 struct page *new_page = NULL;
2319 int page_copied = 0;
2320 const unsigned long mmun_start = vmf->address & PAGE_MASK;
2321 const unsigned long mmun_end = mmun_start + PAGE_SIZE;
2322 struct mem_cgroup *memcg;
2324 if (unlikely(anon_vma_prepare(vma)))
2327 if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
2328 new_page = alloc_zeroed_user_highpage_movable(vma,
2333 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2337 cow_user_page(new_page, old_page, vmf->address, vma);
2340 if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
2343 __SetPageUptodate(new_page);
2345 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2348 * Re-check the pte - we dropped the lock
2350 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
2351 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2353 if (!PageAnon(old_page)) {
2354 dec_mm_counter_fast(mm,
2355 mm_counter_file(old_page));
2356 inc_mm_counter_fast(mm, MM_ANONPAGES);
2359 inc_mm_counter_fast(mm, MM_ANONPAGES);
2361 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2362 entry = mk_pte(new_page, vma->vm_page_prot);
2363 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2365 * Clear the pte entry and flush it first, before updating the
2366 * pte with the new entry. This will avoid a race condition
2367 * seen in the presence of one thread doing SMC and another
2370 ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
2371 page_add_new_anon_rmap(new_page, vma, vmf->address, false);
2372 mem_cgroup_commit_charge(new_page, memcg, false, false);
2373 lru_cache_add_active_or_unevictable(new_page, vma);
2375 * We call the notify macro here because, when using secondary
2376 * mmu page tables (such as kvm shadow page tables), we want the
2377 * new page to be mapped directly into the secondary page table.
2379 set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
2380 update_mmu_cache(vma, vmf->address, vmf->pte);
2383 * Only after switching the pte to the new page may
2384 * we remove the mapcount here. Otherwise another
2385 * process may come and find the rmap count decremented
2386 * before the pte is switched to the new page, and
2387 * "reuse" the old page writing into it while our pte
2388 * here still points into it and can be read by other
2391 * The critical issue is to order this
2392 * page_remove_rmap with the ptp_clear_flush above.
2393 * Those stores are ordered by (if nothing else,)
2394 * the barrier present in the atomic_add_negative
2395 * in page_remove_rmap.
2397 * Then the TLB flush in ptep_clear_flush ensures that
2398 * no process can access the old page before the
2399 * decremented mapcount is visible. And the old page
2400 * cannot be reused until after the decremented
2401 * mapcount is visible. So transitively, TLBs to
2402 * old page will be flushed before it can be reused.
2404 page_remove_rmap(old_page, false);
2407 /* Free the old page.. */
2408 new_page = old_page;
2411 mem_cgroup_cancel_charge(new_page, memcg, false);
2417 pte_unmap_unlock(vmf->pte, vmf->ptl);
2418 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2421 * Don't let another task, with possibly unlocked vma,
2422 * keep the mlocked page.
2424 if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2425 lock_page(old_page); /* LRU manipulation */
2426 if (PageMlocked(old_page))
2427 munlock_vma_page(old_page);
2428 unlock_page(old_page);
2432 return page_copied ? VM_FAULT_WRITE : 0;
2438 return VM_FAULT_OOM;
2442 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
2443 * writeable once the page is prepared
2445 * @vmf: structure describing the fault
2447 * This function handles all that is needed to finish a write page fault in a
2448 * shared mapping due to PTE being read-only once the mapped page is prepared.
2449 * It handles locking of PTE and modifying it. The function returns
2450 * VM_FAULT_WRITE on success, 0 when PTE got changed before we acquired PTE
2453 * The function expects the page to be locked or other protection against
2454 * concurrent faults / writeback (such as DAX radix tree locks).
2456 int finish_mkwrite_fault(struct vm_fault *vmf)
2458 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
2459 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
2462 * We might have raced with another page fault while we released the
2463 * pte_offset_map_lock.
2465 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2466 pte_unmap_unlock(vmf->pte, vmf->ptl);
2467 return VM_FAULT_NOPAGE;
2474 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2477 static int wp_pfn_shared(struct vm_fault *vmf)
2479 struct vm_area_struct *vma = vmf->vma;
2481 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
2484 pte_unmap_unlock(vmf->pte, vmf->ptl);
2485 vmf->flags |= FAULT_FLAG_MKWRITE;
2486 ret = vma->vm_ops->pfn_mkwrite(vmf);
2487 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
2489 return finish_mkwrite_fault(vmf);
2492 return VM_FAULT_WRITE;
2495 static int wp_page_shared(struct vm_fault *vmf)
2496 __releases(vmf->ptl)
2498 struct vm_area_struct *vma = vmf->vma;
2500 get_page(vmf->page);
2502 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2505 pte_unmap_unlock(vmf->pte, vmf->ptl);
2506 tmp = do_page_mkwrite(vmf);
2507 if (unlikely(!tmp || (tmp &
2508 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2509 put_page(vmf->page);
2512 tmp = finish_mkwrite_fault(vmf);
2513 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2514 unlock_page(vmf->page);
2515 put_page(vmf->page);
2520 lock_page(vmf->page);
2522 fault_dirty_shared_page(vma, vmf->page);
2523 put_page(vmf->page);
2525 return VM_FAULT_WRITE;
2529 * This routine handles present pages, when users try to write
2530 * to a shared page. It is done by copying the page to a new address
2531 * and decrementing the shared-page counter for the old page.
2533 * Note that this routine assumes that the protection checks have been
2534 * done by the caller (the low-level page fault routine in most cases).
2535 * Thus we can safely just mark it writable once we've done any necessary
2538 * We also mark the page dirty at this point even though the page will
2539 * change only once the write actually happens. This avoids a few races,
2540 * and potentially makes it more efficient.
2542 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2543 * but allow concurrent faults), with pte both mapped and locked.
2544 * We return with mmap_sem still held, but pte unmapped and unlocked.
2546 static int do_wp_page(struct vm_fault *vmf)
2547 __releases(vmf->ptl)
2549 struct vm_area_struct *vma = vmf->vma;
2551 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
2554 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2557 * We should not cow pages in a shared writeable mapping.
2558 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2560 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2561 (VM_WRITE|VM_SHARED))
2562 return wp_pfn_shared(vmf);
2564 pte_unmap_unlock(vmf->pte, vmf->ptl);
2565 return wp_page_copy(vmf);
2569 * Take out anonymous pages first, anonymous shared vmas are
2570 * not dirty accountable.
2572 if (PageAnon(vmf->page) && !PageKsm(vmf->page)) {
2574 if (!trylock_page(vmf->page)) {
2575 get_page(vmf->page);
2576 pte_unmap_unlock(vmf->pte, vmf->ptl);
2577 lock_page(vmf->page);
2578 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2579 vmf->address, &vmf->ptl);
2580 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2581 unlock_page(vmf->page);
2582 pte_unmap_unlock(vmf->pte, vmf->ptl);
2583 put_page(vmf->page);
2586 put_page(vmf->page);
2588 if (reuse_swap_page(vmf->page, &total_mapcount)) {
2589 if (total_mapcount == 1) {
2591 * The page is all ours. Move it to
2592 * our anon_vma so the rmap code will
2593 * not search our parent or siblings.
2594 * Protected against the rmap code by
2597 page_move_anon_rmap(vmf->page, vma);
2599 unlock_page(vmf->page);
2601 return VM_FAULT_WRITE;
2603 unlock_page(vmf->page);
2604 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2605 (VM_WRITE|VM_SHARED))) {
2606 return wp_page_shared(vmf);
2610 * Ok, we need to copy. Oh, well..
2612 get_page(vmf->page);
2614 pte_unmap_unlock(vmf->pte, vmf->ptl);
2615 return wp_page_copy(vmf);
2618 static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2619 unsigned long start_addr, unsigned long end_addr,
2620 struct zap_details *details)
2622 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2625 static inline void unmap_mapping_range_tree(struct rb_root *root,
2626 struct zap_details *details)
2628 struct vm_area_struct *vma;
2629 pgoff_t vba, vea, zba, zea;
2631 vma_interval_tree_foreach(vma, root,
2632 details->first_index, details->last_index) {
2634 vba = vma->vm_pgoff;
2635 vea = vba + vma_pages(vma) - 1;
2636 zba = details->first_index;
2639 zea = details->last_index;
2643 unmap_mapping_range_vma(vma,
2644 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2645 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2651 * unmap_mapping_range - unmap the portion of all mmaps in the specified
2652 * address_space corresponding to the specified page range in the underlying
2655 * @mapping: the address space containing mmaps to be unmapped.
2656 * @holebegin: byte in first page to unmap, relative to the start of
2657 * the underlying file. This will be rounded down to a PAGE_SIZE
2658 * boundary. Note that this is different from truncate_pagecache(), which
2659 * must keep the partial page. In contrast, we must get rid of
2661 * @holelen: size of prospective hole in bytes. This will be rounded
2662 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2664 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2665 * but 0 when invalidating pagecache, don't throw away private data.
2667 void unmap_mapping_range(struct address_space *mapping,
2668 loff_t const holebegin, loff_t const holelen, int even_cows)
2670 struct zap_details details = { };
2671 pgoff_t hba = holebegin >> PAGE_SHIFT;
2672 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2674 /* Check for overflow. */
2675 if (sizeof(holelen) > sizeof(hlen)) {
2677 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2678 if (holeend & ~(long long)ULONG_MAX)
2679 hlen = ULONG_MAX - hba + 1;
2682 details.check_mapping = even_cows ? NULL : mapping;
2683 details.first_index = hba;
2684 details.last_index = hba + hlen - 1;
2685 if (details.last_index < details.first_index)
2686 details.last_index = ULONG_MAX;
2688 i_mmap_lock_write(mapping);
2689 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
2690 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2691 i_mmap_unlock_write(mapping);
2693 EXPORT_SYMBOL(unmap_mapping_range);
2696 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2697 * but allow concurrent faults), and pte mapped but not yet locked.
2698 * We return with pte unmapped and unlocked.
2700 * We return with the mmap_sem locked or unlocked in the same cases
2701 * as does filemap_fault().
2703 int do_swap_page(struct vm_fault *vmf)
2705 struct vm_area_struct *vma = vmf->vma;
2706 struct page *page, *swapcache;
2707 struct mem_cgroup *memcg;
2714 if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
2717 entry = pte_to_swp_entry(vmf->orig_pte);
2718 if (unlikely(non_swap_entry(entry))) {
2719 if (is_migration_entry(entry)) {
2720 migration_entry_wait(vma->vm_mm, vmf->pmd,
2722 } else if (is_hwpoison_entry(entry)) {
2723 ret = VM_FAULT_HWPOISON;
2725 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
2726 ret = VM_FAULT_SIGBUS;
2730 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2731 page = lookup_swap_cache(entry);
2733 page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, vma,
2737 * Back out if somebody else faulted in this pte
2738 * while we released the pte lock.
2740 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2741 vmf->address, &vmf->ptl);
2742 if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
2744 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2748 /* Had to read the page from swap area: Major fault */
2749 ret = VM_FAULT_MAJOR;
2750 count_vm_event(PGMAJFAULT);
2751 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
2752 } else if (PageHWPoison(page)) {
2754 * hwpoisoned dirty swapcache pages are kept for killing
2755 * owner processes (which may be unknown at hwpoison time)
2757 ret = VM_FAULT_HWPOISON;
2758 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2764 locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
2766 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2768 ret |= VM_FAULT_RETRY;
2773 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2774 * release the swapcache from under us. The page pin, and pte_same
2775 * test below, are not enough to exclude that. Even if it is still
2776 * swapcache, we need to check that the page's swap has not changed.
2778 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
2781 page = ksm_might_need_to_copy(page, vma, vmf->address);
2782 if (unlikely(!page)) {
2788 if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL,
2795 * Back out if somebody else already faulted in this pte.
2797 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
2799 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
2802 if (unlikely(!PageUptodate(page))) {
2803 ret = VM_FAULT_SIGBUS;
2808 * The page isn't present yet, go ahead with the fault.
2810 * Be careful about the sequence of operations here.
2811 * To get its accounting right, reuse_swap_page() must be called
2812 * while the page is counted on swap but not yet in mapcount i.e.
2813 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
2814 * must be called after the swap_free(), or it will never succeed.
2817 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2818 dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
2819 pte = mk_pte(page, vma->vm_page_prot);
2820 if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
2821 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
2822 vmf->flags &= ~FAULT_FLAG_WRITE;
2823 ret |= VM_FAULT_WRITE;
2824 exclusive = RMAP_EXCLUSIVE;
2826 flush_icache_page(vma, page);
2827 if (pte_swp_soft_dirty(vmf->orig_pte))
2828 pte = pte_mksoft_dirty(pte);
2829 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
2830 vmf->orig_pte = pte;
2831 if (page == swapcache) {
2832 do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
2833 mem_cgroup_commit_charge(page, memcg, true, false);
2834 activate_page(page);
2835 } else { /* ksm created a completely new copy */
2836 page_add_new_anon_rmap(page, vma, vmf->address, false);
2837 mem_cgroup_commit_charge(page, memcg, false, false);
2838 lru_cache_add_active_or_unevictable(page, vma);
2842 if (mem_cgroup_swap_full(page) ||
2843 (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
2844 try_to_free_swap(page);
2846 if (page != swapcache) {
2848 * Hold the lock to avoid the swap entry to be reused
2849 * until we take the PT lock for the pte_same() check
2850 * (to avoid false positives from pte_same). For
2851 * further safety release the lock after the swap_free
2852 * so that the swap count won't change under a
2853 * parallel locked swapcache.
2855 unlock_page(swapcache);
2856 put_page(swapcache);
2859 if (vmf->flags & FAULT_FLAG_WRITE) {
2860 ret |= do_wp_page(vmf);
2861 if (ret & VM_FAULT_ERROR)
2862 ret &= VM_FAULT_ERROR;
2866 /* No need to invalidate - it was non-present before */
2867 update_mmu_cache(vma, vmf->address, vmf->pte);
2869 pte_unmap_unlock(vmf->pte, vmf->ptl);
2873 mem_cgroup_cancel_charge(page, memcg, false);
2874 pte_unmap_unlock(vmf->pte, vmf->ptl);
2879 if (page != swapcache) {
2880 unlock_page(swapcache);
2881 put_page(swapcache);
2887 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2888 * but allow concurrent faults), and pte mapped but not yet locked.
2889 * We return with mmap_sem still held, but pte unmapped and unlocked.
2891 static int do_anonymous_page(struct vm_fault *vmf)
2893 struct vm_area_struct *vma = vmf->vma;
2894 struct mem_cgroup *memcg;
2898 /* File mapping without ->vm_ops ? */
2899 if (vma->vm_flags & VM_SHARED)
2900 return VM_FAULT_SIGBUS;
2903 * Use pte_alloc() instead of pte_alloc_map(). We can't run
2904 * pte_offset_map() on pmds where a huge pmd might be created
2905 * from a different thread.
2907 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
2908 * parallel threads are excluded by other means.
2910 * Here we only have down_read(mmap_sem).
2912 if (pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))
2913 return VM_FAULT_OOM;
2915 /* See the comment in pte_alloc_one_map() */
2916 if (unlikely(pmd_trans_unstable(vmf->pmd)))
2919 /* Use the zero-page for reads */
2920 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
2921 !mm_forbids_zeropage(vma->vm_mm)) {
2922 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
2923 vma->vm_page_prot));
2924 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2925 vmf->address, &vmf->ptl);
2926 if (!pte_none(*vmf->pte))
2928 /* Deliver the page fault to userland, check inside PT lock */
2929 if (userfaultfd_missing(vma)) {
2930 pte_unmap_unlock(vmf->pte, vmf->ptl);
2931 return handle_userfault(vmf, VM_UFFD_MISSING);
2936 /* Allocate our own private page. */
2937 if (unlikely(anon_vma_prepare(vma)))
2939 page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
2943 if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false))
2947 * The memory barrier inside __SetPageUptodate makes sure that
2948 * preceeding stores to the page contents become visible before
2949 * the set_pte_at() write.
2951 __SetPageUptodate(page);
2953 entry = mk_pte(page, vma->vm_page_prot);
2954 if (vma->vm_flags & VM_WRITE)
2955 entry = pte_mkwrite(pte_mkdirty(entry));
2957 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
2959 if (!pte_none(*vmf->pte))
2962 /* Deliver the page fault to userland, check inside PT lock */
2963 if (userfaultfd_missing(vma)) {
2964 pte_unmap_unlock(vmf->pte, vmf->ptl);
2965 mem_cgroup_cancel_charge(page, memcg, false);
2967 return handle_userfault(vmf, VM_UFFD_MISSING);
2970 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
2971 page_add_new_anon_rmap(page, vma, vmf->address, false);
2972 mem_cgroup_commit_charge(page, memcg, false, false);
2973 lru_cache_add_active_or_unevictable(page, vma);
2975 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
2977 /* No need to invalidate - it was non-present before */
2978 update_mmu_cache(vma, vmf->address, vmf->pte);
2980 pte_unmap_unlock(vmf->pte, vmf->ptl);
2983 mem_cgroup_cancel_charge(page, memcg, false);
2989 return VM_FAULT_OOM;
2993 * The mmap_sem must have been held on entry, and may have been
2994 * released depending on flags and vma->vm_ops->fault() return value.
2995 * See filemap_fault() and __lock_page_retry().
2997 static int __do_fault(struct vm_fault *vmf)
2999 struct vm_area_struct *vma = vmf->vma;
3002 ret = vma->vm_ops->fault(vmf);
3003 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
3004 VM_FAULT_DONE_COW)))
3007 if (unlikely(PageHWPoison(vmf->page))) {
3008 if (ret & VM_FAULT_LOCKED)
3009 unlock_page(vmf->page);
3010 put_page(vmf->page);
3012 return VM_FAULT_HWPOISON;
3015 if (unlikely(!(ret & VM_FAULT_LOCKED)))
3016 lock_page(vmf->page);
3018 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
3024 * The ordering of these checks is important for pmds with _PAGE_DEVMAP set.
3025 * If we check pmd_trans_unstable() first we will trip the bad_pmd() check
3026 * inside of pmd_none_or_trans_huge_or_clear_bad(). This will end up correctly
3027 * returning 1 but not before it spams dmesg with the pmd_clear_bad() output.
3029 static int pmd_devmap_trans_unstable(pmd_t *pmd)
3031 return pmd_devmap(*pmd) || pmd_trans_unstable(pmd);
3034 static int pte_alloc_one_map(struct vm_fault *vmf)
3036 struct vm_area_struct *vma = vmf->vma;
3038 if (!pmd_none(*vmf->pmd))
3040 if (vmf->prealloc_pte) {
3041 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3042 if (unlikely(!pmd_none(*vmf->pmd))) {
3043 spin_unlock(vmf->ptl);
3047 atomic_long_inc(&vma->vm_mm->nr_ptes);
3048 pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3049 spin_unlock(vmf->ptl);
3050 vmf->prealloc_pte = NULL;
3051 } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))) {
3052 return VM_FAULT_OOM;
3056 * If a huge pmd materialized under us just retry later. Use
3057 * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead of
3058 * pmd_trans_huge() to ensure the pmd didn't become pmd_trans_huge
3059 * under us and then back to pmd_none, as a result of MADV_DONTNEED
3060 * running immediately after a huge pmd fault in a different thread of
3061 * this mm, in turn leading to a misleading pmd_trans_huge() retval.
3062 * All we have to ensure is that it is a regular pmd that we can walk
3063 * with pte_offset_map() and we can do that through an atomic read in
3064 * C, which is what pmd_trans_unstable() provides.
3066 if (pmd_devmap_trans_unstable(vmf->pmd))
3067 return VM_FAULT_NOPAGE;
3070 * At this point we know that our vmf->pmd points to a page of ptes
3071 * and it cannot become pmd_none(), pmd_devmap() or pmd_trans_huge()
3072 * for the duration of the fault. If a racing MADV_DONTNEED runs and
3073 * we zap the ptes pointed to by our vmf->pmd, the vmf->ptl will still
3074 * be valid and we will re-check to make sure the vmf->pte isn't
3075 * pte_none() under vmf->ptl protection when we return to
3078 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3083 #ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3085 #define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
3086 static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
3087 unsigned long haddr)
3089 if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
3090 (vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK))
3092 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
3097 static void deposit_prealloc_pte(struct vm_fault *vmf)
3099 struct vm_area_struct *vma = vmf->vma;
3101 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3103 * We are going to consume the prealloc table,
3104 * count that as nr_ptes.
3106 atomic_long_inc(&vma->vm_mm->nr_ptes);
3107 vmf->prealloc_pte = NULL;
3110 static int do_set_pmd(struct vm_fault *vmf, struct page *page)
3112 struct vm_area_struct *vma = vmf->vma;
3113 bool write = vmf->flags & FAULT_FLAG_WRITE;
3114 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
3118 if (!transhuge_vma_suitable(vma, haddr))
3119 return VM_FAULT_FALLBACK;
3121 ret = VM_FAULT_FALLBACK;
3122 page = compound_head(page);
3125 * Archs like ppc64 need additonal space to store information
3126 * related to pte entry. Use the preallocated table for that.
3128 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
3129 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm, vmf->address);
3130 if (!vmf->prealloc_pte)
3131 return VM_FAULT_OOM;
3132 smp_wmb(); /* See comment in __pte_alloc() */
3135 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3136 if (unlikely(!pmd_none(*vmf->pmd)))
3139 for (i = 0; i < HPAGE_PMD_NR; i++)
3140 flush_icache_page(vma, page + i);
3142 entry = mk_huge_pmd(page, vma->vm_page_prot);
3144 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
3146 add_mm_counter(vma->vm_mm, MM_FILEPAGES, HPAGE_PMD_NR);
3147 page_add_file_rmap(page, true);
3149 * deposit and withdraw with pmd lock held
3151 if (arch_needs_pgtable_deposit())
3152 deposit_prealloc_pte(vmf);
3154 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
3156 update_mmu_cache_pmd(vma, haddr, vmf->pmd);
3158 /* fault is handled */
3160 count_vm_event(THP_FILE_MAPPED);
3162 spin_unlock(vmf->ptl);
3166 static int do_set_pmd(struct vm_fault *vmf, struct page *page)
3174 * alloc_set_pte - setup new PTE entry for given page and add reverse page
3175 * mapping. If needed, the fucntion allocates page table or use pre-allocated.
3177 * @vmf: fault environment
3178 * @memcg: memcg to charge page (only for private mappings)
3179 * @page: page to map
3181 * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on
3184 * Target users are page handler itself and implementations of
3185 * vm_ops->map_pages.
3187 int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
3190 struct vm_area_struct *vma = vmf->vma;
3191 bool write = vmf->flags & FAULT_FLAG_WRITE;
3195 if (pmd_none(*vmf->pmd) && PageTransCompound(page) &&
3196 IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
3198 VM_BUG_ON_PAGE(memcg, page);
3200 ret = do_set_pmd(vmf, page);
3201 if (ret != VM_FAULT_FALLBACK)
3206 ret = pte_alloc_one_map(vmf);
3211 /* Re-check under ptl */
3212 if (unlikely(!pte_none(*vmf->pte)))
3213 return VM_FAULT_NOPAGE;
3215 flush_icache_page(vma, page);
3216 entry = mk_pte(page, vma->vm_page_prot);
3218 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3219 /* copy-on-write page */
3220 if (write && !(vma->vm_flags & VM_SHARED)) {
3221 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3222 page_add_new_anon_rmap(page, vma, vmf->address, false);
3223 mem_cgroup_commit_charge(page, memcg, false, false);
3224 lru_cache_add_active_or_unevictable(page, vma);
3226 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
3227 page_add_file_rmap(page, false);
3229 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3231 /* no need to invalidate: a not-present page won't be cached */
3232 update_mmu_cache(vma, vmf->address, vmf->pte);
3239 * finish_fault - finish page fault once we have prepared the page to fault
3241 * @vmf: structure describing the fault
3243 * This function handles all that is needed to finish a page fault once the
3244 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
3245 * given page, adds reverse page mapping, handles memcg charges and LRU
3246 * addition. The function returns 0 on success, VM_FAULT_ code in case of
3249 * The function expects the page to be locked and on success it consumes a
3250 * reference of a page being mapped (for the PTE which maps it).
3252 int finish_fault(struct vm_fault *vmf)
3257 /* Did we COW the page? */
3258 if ((vmf->flags & FAULT_FLAG_WRITE) &&
3259 !(vmf->vma->vm_flags & VM_SHARED))
3260 page = vmf->cow_page;
3263 ret = alloc_set_pte(vmf, vmf->memcg, page);
3265 pte_unmap_unlock(vmf->pte, vmf->ptl);
3269 static unsigned long fault_around_bytes __read_mostly =
3270 rounddown_pow_of_two(65536);
3272 #ifdef CONFIG_DEBUG_FS
3273 static int fault_around_bytes_get(void *data, u64 *val)
3275 *val = fault_around_bytes;
3280 * fault_around_pages() and fault_around_mask() expects fault_around_bytes
3281 * rounded down to nearest page order. It's what do_fault_around() expects to
3284 static int fault_around_bytes_set(void *data, u64 val)
3286 if (val / PAGE_SIZE > PTRS_PER_PTE)
3288 if (val > PAGE_SIZE)
3289 fault_around_bytes = rounddown_pow_of_two(val);
3291 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
3294 DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
3295 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3297 static int __init fault_around_debugfs(void)
3301 ret = debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
3302 &fault_around_bytes_fops);
3304 pr_warn("Failed to create fault_around_bytes in debugfs");
3307 late_initcall(fault_around_debugfs);
3311 * do_fault_around() tries to map few pages around the fault address. The hope
3312 * is that the pages will be needed soon and this will lower the number of
3315 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3316 * not ready to be mapped: not up-to-date, locked, etc.
3318 * This function is called with the page table lock taken. In the split ptlock
3319 * case the page table lock only protects only those entries which belong to
3320 * the page table corresponding to the fault address.
3322 * This function doesn't cross the VMA boundaries, in order to call map_pages()
3325 * fault_around_pages() defines how many pages we'll try to map.
3326 * do_fault_around() expects it to return a power of two less than or equal to
3329 * The virtual address of the area that we map is naturally aligned to the
3330 * fault_around_pages() value (and therefore to page order). This way it's
3331 * easier to guarantee that we don't cross page table boundaries.
3333 static int do_fault_around(struct vm_fault *vmf)
3335 unsigned long address = vmf->address, nr_pages, mask;
3336 pgoff_t start_pgoff = vmf->pgoff;
3340 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3341 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
3343 vmf->address = max(address & mask, vmf->vma->vm_start);
3344 off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
3348 * end_pgoff is either end of page table or end of vma
3349 * or fault_around_pages() from start_pgoff, depending what is nearest.
3351 end_pgoff = start_pgoff -
3352 ((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3354 end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
3355 start_pgoff + nr_pages - 1);
3357 if (pmd_none(*vmf->pmd)) {
3358 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm,
3360 if (!vmf->prealloc_pte)
3362 smp_wmb(); /* See comment in __pte_alloc() */
3365 vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
3367 /* Huge page is mapped? Page fault is solved */
3368 if (pmd_trans_huge(*vmf->pmd)) {
3369 ret = VM_FAULT_NOPAGE;
3373 /* ->map_pages() haven't done anything useful. Cold page cache? */
3377 /* check if the page fault is solved */
3378 vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
3379 if (!pte_none(*vmf->pte))
3380 ret = VM_FAULT_NOPAGE;
3381 pte_unmap_unlock(vmf->pte, vmf->ptl);
3383 vmf->address = address;
3388 static int do_read_fault(struct vm_fault *vmf)
3390 struct vm_area_struct *vma = vmf->vma;
3394 * Let's call ->map_pages() first and use ->fault() as fallback
3395 * if page by the offset is not ready to be mapped (cold cache or
3398 if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3399 ret = do_fault_around(vmf);
3404 ret = __do_fault(vmf);
3405 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3408 ret |= finish_fault(vmf);
3409 unlock_page(vmf->page);
3410 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3411 put_page(vmf->page);
3415 static int do_cow_fault(struct vm_fault *vmf)
3417 struct vm_area_struct *vma = vmf->vma;
3420 if (unlikely(anon_vma_prepare(vma)))
3421 return VM_FAULT_OOM;
3423 vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
3425 return VM_FAULT_OOM;
3427 if (mem_cgroup_try_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
3428 &vmf->memcg, false)) {
3429 put_page(vmf->cow_page);
3430 return VM_FAULT_OOM;
3433 ret = __do_fault(vmf);
3434 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3436 if (ret & VM_FAULT_DONE_COW)
3439 copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
3440 __SetPageUptodate(vmf->cow_page);
3442 ret |= finish_fault(vmf);
3443 unlock_page(vmf->page);
3444 put_page(vmf->page);
3445 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3449 mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false);
3450 put_page(vmf->cow_page);
3454 static int do_shared_fault(struct vm_fault *vmf)
3456 struct vm_area_struct *vma = vmf->vma;
3459 ret = __do_fault(vmf);
3460 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3464 * Check if the backing address space wants to know that the page is
3465 * about to become writable
3467 if (vma->vm_ops->page_mkwrite) {
3468 unlock_page(vmf->page);
3469 tmp = do_page_mkwrite(vmf);
3470 if (unlikely(!tmp ||
3471 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3472 put_page(vmf->page);
3477 ret |= finish_fault(vmf);
3478 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3480 unlock_page(vmf->page);
3481 put_page(vmf->page);
3485 fault_dirty_shared_page(vma, vmf->page);
3490 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3491 * but allow concurrent faults).
3492 * The mmap_sem may have been released depending on flags and our
3493 * return value. See filemap_fault() and __lock_page_or_retry().
3495 static int do_fault(struct vm_fault *vmf)
3497 struct vm_area_struct *vma = vmf->vma;
3500 /* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
3501 if (!vma->vm_ops->fault)
3502 ret = VM_FAULT_SIGBUS;
3503 else if (!(vmf->flags & FAULT_FLAG_WRITE))
3504 ret = do_read_fault(vmf);
3505 else if (!(vma->vm_flags & VM_SHARED))
3506 ret = do_cow_fault(vmf);
3508 ret = do_shared_fault(vmf);
3510 /* preallocated pagetable is unused: free it */
3511 if (vmf->prealloc_pte) {
3512 pte_free(vma->vm_mm, vmf->prealloc_pte);
3513 vmf->prealloc_pte = NULL;
3518 static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3519 unsigned long addr, int page_nid,
3524 count_vm_numa_event(NUMA_HINT_FAULTS);
3525 if (page_nid == numa_node_id()) {
3526 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3527 *flags |= TNF_FAULT_LOCAL;
3530 return mpol_misplaced(page, vma, addr);
3533 static int do_numa_page(struct vm_fault *vmf)
3535 struct vm_area_struct *vma = vmf->vma;
3536 struct page *page = NULL;
3540 bool migrated = false;
3542 bool was_writable = pte_savedwrite(vmf->orig_pte);
3546 * The "pte" at this point cannot be used safely without
3547 * validation through pte_unmap_same(). It's of NUMA type but
3548 * the pfn may be screwed if the read is non atomic.
3550 vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
3551 spin_lock(vmf->ptl);
3552 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
3553 pte_unmap_unlock(vmf->pte, vmf->ptl);
3558 * Make it present again, Depending on how arch implementes non
3559 * accessible ptes, some can allow access by kernel mode.
3561 pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte);
3562 pte = pte_modify(pte, vma->vm_page_prot);
3563 pte = pte_mkyoung(pte);
3565 pte = pte_mkwrite(pte);
3566 ptep_modify_prot_commit(vma->vm_mm, vmf->address, vmf->pte, pte);
3567 update_mmu_cache(vma, vmf->address, vmf->pte);
3569 page = vm_normal_page(vma, vmf->address, pte);
3571 pte_unmap_unlock(vmf->pte, vmf->ptl);
3575 /* TODO: handle PTE-mapped THP */
3576 if (PageCompound(page)) {
3577 pte_unmap_unlock(vmf->pte, vmf->ptl);
3582 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
3583 * much anyway since they can be in shared cache state. This misses
3584 * the case where a mapping is writable but the process never writes
3585 * to it but pte_write gets cleared during protection updates and
3586 * pte_dirty has unpredictable behaviour between PTE scan updates,
3587 * background writeback, dirty balancing and application behaviour.
3589 if (!pte_write(pte))
3590 flags |= TNF_NO_GROUP;
3593 * Flag if the page is shared between multiple address spaces. This
3594 * is later used when determining whether to group tasks together
3596 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3597 flags |= TNF_SHARED;
3599 last_cpupid = page_cpupid_last(page);
3600 page_nid = page_to_nid(page);
3601 target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
3603 pte_unmap_unlock(vmf->pte, vmf->ptl);
3604 if (target_nid == -1) {
3609 /* Migrate to the requested node */
3610 migrated = migrate_misplaced_page(page, vma, target_nid);
3612 page_nid = target_nid;
3613 flags |= TNF_MIGRATED;
3615 flags |= TNF_MIGRATE_FAIL;
3619 task_numa_fault(last_cpupid, page_nid, 1, flags);
3623 static inline int create_huge_pmd(struct vm_fault *vmf)
3625 if (vma_is_anonymous(vmf->vma))
3626 return do_huge_pmd_anonymous_page(vmf);
3627 if (vmf->vma->vm_ops->huge_fault)
3628 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3629 return VM_FAULT_FALLBACK;
3632 static int wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
3634 if (vma_is_anonymous(vmf->vma))
3635 return do_huge_pmd_wp_page(vmf, orig_pmd);
3636 if (vmf->vma->vm_ops->huge_fault)
3637 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3639 /* COW handled on pte level: split pmd */
3640 VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);
3641 __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
3643 return VM_FAULT_FALLBACK;
3646 static inline bool vma_is_accessible(struct vm_area_struct *vma)
3648 return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
3651 static int create_huge_pud(struct vm_fault *vmf)
3653 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3654 /* No support for anonymous transparent PUD pages yet */
3655 if (vma_is_anonymous(vmf->vma))
3656 return VM_FAULT_FALLBACK;
3657 if (vmf->vma->vm_ops->huge_fault)
3658 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3659 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3660 return VM_FAULT_FALLBACK;
3663 static int wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
3665 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
3666 /* No support for anonymous transparent PUD pages yet */
3667 if (vma_is_anonymous(vmf->vma))
3668 return VM_FAULT_FALLBACK;
3669 if (vmf->vma->vm_ops->huge_fault)
3670 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3671 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3672 return VM_FAULT_FALLBACK;
3676 * These routines also need to handle stuff like marking pages dirty
3677 * and/or accessed for architectures that don't do it in hardware (most
3678 * RISC architectures). The early dirtying is also good on the i386.
3680 * There is also a hook called "update_mmu_cache()" that architectures
3681 * with external mmu caches can use to update those (ie the Sparc or
3682 * PowerPC hashed page tables that act as extended TLBs).
3684 * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
3685 * concurrent faults).
3687 * The mmap_sem may have been released depending on flags and our return value.
3688 * See filemap_fault() and __lock_page_or_retry().
3690 static int handle_pte_fault(struct vm_fault *vmf)
3694 if (unlikely(pmd_none(*vmf->pmd))) {
3696 * Leave __pte_alloc() until later: because vm_ops->fault may
3697 * want to allocate huge page, and if we expose page table
3698 * for an instant, it will be difficult to retract from
3699 * concurrent faults and from rmap lookups.
3703 /* See comment in pte_alloc_one_map() */
3704 if (pmd_devmap_trans_unstable(vmf->pmd))
3707 * A regular pmd is established and it can't morph into a huge
3708 * pmd from under us anymore at this point because we hold the
3709 * mmap_sem read mode and khugepaged takes it in write mode.
3710 * So now it's safe to run pte_offset_map().
3712 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
3713 vmf->orig_pte = *vmf->pte;
3716 * some architectures can have larger ptes than wordsize,
3717 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
3718 * CONFIG_32BIT=y, so READ_ONCE or ACCESS_ONCE cannot guarantee
3719 * atomic accesses. The code below just needs a consistent
3720 * view for the ifs and we later double check anyway with the
3721 * ptl lock held. So here a barrier will do.
3724 if (pte_none(vmf->orig_pte)) {
3725 pte_unmap(vmf->pte);
3731 if (vma_is_anonymous(vmf->vma))
3732 return do_anonymous_page(vmf);
3734 return do_fault(vmf);
3737 if (!pte_present(vmf->orig_pte))
3738 return do_swap_page(vmf);
3740 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
3741 return do_numa_page(vmf);
3743 vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
3744 spin_lock(vmf->ptl);
3745 entry = vmf->orig_pte;
3746 if (unlikely(!pte_same(*vmf->pte, entry)))
3748 if (vmf->flags & FAULT_FLAG_WRITE) {
3749 if (!pte_write(entry))
3750 return do_wp_page(vmf);
3751 entry = pte_mkdirty(entry);
3753 entry = pte_mkyoung(entry);
3754 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
3755 vmf->flags & FAULT_FLAG_WRITE)) {
3756 update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
3759 * This is needed only for protection faults but the arch code
3760 * is not yet telling us if this is a protection fault or not.
3761 * This still avoids useless tlb flushes for .text page faults
3764 if (vmf->flags & FAULT_FLAG_WRITE)
3765 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
3768 pte_unmap_unlock(vmf->pte, vmf->ptl);
3773 * By the time we get here, we already hold the mm semaphore
3775 * The mmap_sem may have been released depending on flags and our
3776 * return value. See filemap_fault() and __lock_page_or_retry().
3778 static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
3781 struct vm_fault vmf = {
3783 .address = address & PAGE_MASK,
3785 .pgoff = linear_page_index(vma, address),
3786 .gfp_mask = __get_fault_gfp_mask(vma),
3788 struct mm_struct *mm = vma->vm_mm;
3793 pgd = pgd_offset(mm, address);
3794 p4d = p4d_alloc(mm, pgd, address);
3796 return VM_FAULT_OOM;
3798 vmf.pud = pud_alloc(mm, p4d, address);
3800 return VM_FAULT_OOM;
3801 if (pud_none(*vmf.pud) && transparent_hugepage_enabled(vma)) {
3802 ret = create_huge_pud(&vmf);
3803 if (!(ret & VM_FAULT_FALLBACK))
3806 pud_t orig_pud = *vmf.pud;
3809 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
3810 unsigned int dirty = flags & FAULT_FLAG_WRITE;
3812 /* NUMA case for anonymous PUDs would go here */
3814 if (dirty && !pud_write(orig_pud)) {
3815 ret = wp_huge_pud(&vmf, orig_pud);
3816 if (!(ret & VM_FAULT_FALLBACK))
3819 huge_pud_set_accessed(&vmf, orig_pud);
3825 vmf.pmd = pmd_alloc(mm, vmf.pud, address);
3827 return VM_FAULT_OOM;
3828 if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) {
3829 ret = create_huge_pmd(&vmf);
3830 if (!(ret & VM_FAULT_FALLBACK))
3833 pmd_t orig_pmd = *vmf.pmd;
3836 if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
3837 if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
3838 return do_huge_pmd_numa_page(&vmf, orig_pmd);
3840 if ((vmf.flags & FAULT_FLAG_WRITE) &&
3841 !pmd_write(orig_pmd)) {
3842 ret = wp_huge_pmd(&vmf, orig_pmd);
3843 if (!(ret & VM_FAULT_FALLBACK))
3846 huge_pmd_set_accessed(&vmf, orig_pmd);
3852 return handle_pte_fault(&vmf);
3856 * By the time we get here, we already hold the mm semaphore
3858 * The mmap_sem may have been released depending on flags and our
3859 * return value. See filemap_fault() and __lock_page_or_retry().
3861 int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
3866 __set_current_state(TASK_RUNNING);
3868 count_vm_event(PGFAULT);
3869 count_memcg_event_mm(vma->vm_mm, PGFAULT);
3871 /* do counter updates before entering really critical section. */
3872 check_sync_rss_stat(current);
3875 * Enable the memcg OOM handling for faults triggered in user
3876 * space. Kernel faults are handled more gracefully.
3878 if (flags & FAULT_FLAG_USER)
3879 mem_cgroup_oom_enable();
3881 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
3882 flags & FAULT_FLAG_INSTRUCTION,
3883 flags & FAULT_FLAG_REMOTE))
3884 return VM_FAULT_SIGSEGV;
3886 if (unlikely(is_vm_hugetlb_page(vma)))
3887 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
3889 ret = __handle_mm_fault(vma, address, flags);
3891 if (flags & FAULT_FLAG_USER) {
3892 mem_cgroup_oom_disable();
3894 * The task may have entered a memcg OOM situation but
3895 * if the allocation error was handled gracefully (no
3896 * VM_FAULT_OOM), there is no need to kill anything.
3897 * Just clean up the OOM state peacefully.
3899 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
3900 mem_cgroup_oom_synchronize(false);
3904 * This mm has been already reaped by the oom reaper and so the
3905 * refault cannot be trusted in general. Anonymous refaults would
3906 * lose data and give a zero page instead e.g. This is especially
3907 * problem for use_mm() because regular tasks will just die and
3908 * the corrupted data will not be visible anywhere while kthread
3909 * will outlive the oom victim and potentially propagate the date
3912 if (unlikely((current->flags & PF_KTHREAD) && !(ret & VM_FAULT_ERROR)
3913 && test_bit(MMF_UNSTABLE, &vma->vm_mm->flags)))
3914 ret = VM_FAULT_SIGBUS;
3918 EXPORT_SYMBOL_GPL(handle_mm_fault);
3920 #ifndef __PAGETABLE_P4D_FOLDED
3922 * Allocate p4d page table.
3923 * We've already handled the fast-path in-line.
3925 int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3927 p4d_t *new = p4d_alloc_one(mm, address);
3931 smp_wmb(); /* See comment in __pte_alloc */
3933 spin_lock(&mm->page_table_lock);
3934 if (pgd_present(*pgd)) /* Another has populated it */
3937 pgd_populate(mm, pgd, new);
3938 spin_unlock(&mm->page_table_lock);
3941 #endif /* __PAGETABLE_P4D_FOLDED */
3943 #ifndef __PAGETABLE_PUD_FOLDED
3945 * Allocate page upper directory.
3946 * We've already handled the fast-path in-line.
3948 int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
3950 pud_t *new = pud_alloc_one(mm, address);
3954 smp_wmb(); /* See comment in __pte_alloc */
3956 spin_lock(&mm->page_table_lock);
3957 #ifndef __ARCH_HAS_5LEVEL_HACK
3958 if (p4d_present(*p4d)) /* Another has populated it */
3961 p4d_populate(mm, p4d, new);
3963 if (pgd_present(*p4d)) /* Another has populated it */
3966 pgd_populate(mm, p4d, new);
3967 #endif /* __ARCH_HAS_5LEVEL_HACK */
3968 spin_unlock(&mm->page_table_lock);
3971 #endif /* __PAGETABLE_PUD_FOLDED */
3973 #ifndef __PAGETABLE_PMD_FOLDED
3975 * Allocate page middle directory.
3976 * We've already handled the fast-path in-line.
3978 int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
3981 pmd_t *new = pmd_alloc_one(mm, address);
3985 smp_wmb(); /* See comment in __pte_alloc */
3987 ptl = pud_lock(mm, pud);
3988 #ifndef __ARCH_HAS_4LEVEL_HACK
3989 if (!pud_present(*pud)) {
3991 pud_populate(mm, pud, new);
3992 } else /* Another has populated it */
3995 if (!pgd_present(*pud)) {
3997 pgd_populate(mm, pud, new);
3998 } else /* Another has populated it */
4000 #endif /* __ARCH_HAS_4LEVEL_HACK */
4004 #endif /* __PAGETABLE_PMD_FOLDED */
4006 static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4007 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4015 pgd = pgd_offset(mm, address);
4016 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
4019 p4d = p4d_offset(pgd, address);
4020 if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
4023 pud = pud_offset(p4d, address);
4024 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
4027 pmd = pmd_offset(pud, address);
4028 VM_BUG_ON(pmd_trans_huge(*pmd));
4030 if (pmd_huge(*pmd)) {
4034 *ptlp = pmd_lock(mm, pmd);
4035 if (pmd_huge(*pmd)) {
4042 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
4045 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
4046 if (!pte_present(*ptep))
4051 pte_unmap_unlock(ptep, *ptlp);
4056 static inline int follow_pte(struct mm_struct *mm, unsigned long address,
4057 pte_t **ptepp, spinlock_t **ptlp)
4061 /* (void) is needed to make gcc happy */
4062 (void) __cond_lock(*ptlp,
4063 !(res = __follow_pte_pmd(mm, address, ptepp, NULL,
4068 int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4069 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4073 /* (void) is needed to make gcc happy */
4074 (void) __cond_lock(*ptlp,
4075 !(res = __follow_pte_pmd(mm, address, ptepp, pmdpp,
4079 EXPORT_SYMBOL(follow_pte_pmd);
4082 * follow_pfn - look up PFN at a user virtual address
4083 * @vma: memory mapping
4084 * @address: user virtual address
4085 * @pfn: location to store found PFN
4087 * Only IO mappings and raw PFN mappings are allowed.
4089 * Returns zero and the pfn at @pfn on success, -ve otherwise.
4091 int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4098 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4101 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4104 *pfn = pte_pfn(*ptep);
4105 pte_unmap_unlock(ptep, ptl);
4108 EXPORT_SYMBOL(follow_pfn);
4110 #ifdef CONFIG_HAVE_IOREMAP_PROT
4111 int follow_phys(struct vm_area_struct *vma,
4112 unsigned long address, unsigned int flags,
4113 unsigned long *prot, resource_size_t *phys)
4119 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4122 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4126 if ((flags & FOLL_WRITE) && !pte_write(pte))
4129 *prot = pgprot_val(pte_pgprot(pte));
4130 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4134 pte_unmap_unlock(ptep, ptl);
4139 int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4140 void *buf, int len, int write)
4142 resource_size_t phys_addr;
4143 unsigned long prot = 0;
4144 void __iomem *maddr;
4145 int offset = addr & (PAGE_SIZE-1);
4147 if (follow_phys(vma, addr, write, &prot, &phys_addr))
4150 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
4152 memcpy_toio(maddr + offset, buf, len);
4154 memcpy_fromio(buf, maddr + offset, len);
4159 EXPORT_SYMBOL_GPL(generic_access_phys);
4163 * Access another process' address space as given in mm. If non-NULL, use the
4164 * given task for page fault accounting.
4166 int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
4167 unsigned long addr, void *buf, int len, unsigned int gup_flags)
4169 struct vm_area_struct *vma;
4170 void *old_buf = buf;
4171 int write = gup_flags & FOLL_WRITE;
4173 down_read(&mm->mmap_sem);
4174 /* ignore errors, just check how much was successfully transferred */
4176 int bytes, ret, offset;
4178 struct page *page = NULL;
4180 ret = get_user_pages_remote(tsk, mm, addr, 1,
4181 gup_flags, &page, &vma, NULL);
4183 #ifndef CONFIG_HAVE_IOREMAP_PROT
4187 * Check if this is a VM_IO | VM_PFNMAP VMA, which
4188 * we can access using slightly different code.
4190 vma = find_vma(mm, addr);
4191 if (!vma || vma->vm_start > addr)
4193 if (vma->vm_ops && vma->vm_ops->access)
4194 ret = vma->vm_ops->access(vma, addr, buf,
4202 offset = addr & (PAGE_SIZE-1);
4203 if (bytes > PAGE_SIZE-offset)
4204 bytes = PAGE_SIZE-offset;
4208 copy_to_user_page(vma, page, addr,
4209 maddr + offset, buf, bytes);
4210 set_page_dirty_lock(page);
4212 copy_from_user_page(vma, page, addr,
4213 buf, maddr + offset, bytes);
4222 up_read(&mm->mmap_sem);
4224 return buf - old_buf;
4228 * access_remote_vm - access another process' address space
4229 * @mm: the mm_struct of the target address space
4230 * @addr: start address to access
4231 * @buf: source or destination buffer
4232 * @len: number of bytes to transfer
4233 * @gup_flags: flags modifying lookup behaviour
4235 * The caller must hold a reference on @mm.
4237 int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4238 void *buf, int len, unsigned int gup_flags)
4240 return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
4244 * Access another process' address space.
4245 * Source/target buffer must be kernel space,
4246 * Do not walk the page table directly, use get_user_pages
4248 int access_process_vm(struct task_struct *tsk, unsigned long addr,
4249 void *buf, int len, unsigned int gup_flags)
4251 struct mm_struct *mm;
4254 mm = get_task_mm(tsk);
4258 ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
4264 EXPORT_SYMBOL_GPL(access_process_vm);
4267 * Print the name of a VMA.
4269 void print_vma_addr(char *prefix, unsigned long ip)
4271 struct mm_struct *mm = current->mm;
4272 struct vm_area_struct *vma;
4275 * Do not print if we are in atomic
4276 * contexts (in exception stacks, etc.):
4278 if (preempt_count())
4281 down_read(&mm->mmap_sem);
4282 vma = find_vma(mm, ip);
4283 if (vma && vma->vm_file) {
4284 struct file *f = vma->vm_file;
4285 char *buf = (char *)__get_free_page(GFP_KERNEL);
4289 p = file_path(f, buf, PAGE_SIZE);
4292 printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4294 vma->vm_end - vma->vm_start);
4295 free_page((unsigned long)buf);
4298 up_read(&mm->mmap_sem);
4301 #if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4302 void __might_fault(const char *file, int line)
4305 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4306 * holding the mmap_sem, this is safe because kernel memory doesn't
4307 * get paged out, therefore we'll never actually fault, and the
4308 * below annotations will generate false positives.
4310 if (uaccess_kernel())
4312 if (pagefault_disabled())
4314 __might_sleep(file, line, 0);
4315 #if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4317 might_lock_read(¤t->mm->mmap_sem);
4320 EXPORT_SYMBOL(__might_fault);
4323 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4324 static void clear_gigantic_page(struct page *page,
4326 unsigned int pages_per_huge_page)
4329 struct page *p = page;
4332 for (i = 0; i < pages_per_huge_page;
4333 i++, p = mem_map_next(p, page, i)) {
4335 clear_user_highpage(p, addr + i * PAGE_SIZE);
4338 void clear_huge_page(struct page *page,
4339 unsigned long addr, unsigned int pages_per_huge_page)
4343 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4344 clear_gigantic_page(page, addr, pages_per_huge_page);
4349 for (i = 0; i < pages_per_huge_page; i++) {
4351 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4355 static void copy_user_gigantic_page(struct page *dst, struct page *src,
4357 struct vm_area_struct *vma,
4358 unsigned int pages_per_huge_page)
4361 struct page *dst_base = dst;
4362 struct page *src_base = src;
4364 for (i = 0; i < pages_per_huge_page; ) {
4366 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4369 dst = mem_map_next(dst, dst_base, i);
4370 src = mem_map_next(src, src_base, i);
4374 void copy_user_huge_page(struct page *dst, struct page *src,
4375 unsigned long addr, struct vm_area_struct *vma,
4376 unsigned int pages_per_huge_page)
4380 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4381 copy_user_gigantic_page(dst, src, addr, vma,
4382 pages_per_huge_page);
4387 for (i = 0; i < pages_per_huge_page; i++) {
4389 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
4393 long copy_huge_page_from_user(struct page *dst_page,
4394 const void __user *usr_src,
4395 unsigned int pages_per_huge_page,
4396 bool allow_pagefault)
4398 void *src = (void *)usr_src;
4400 unsigned long i, rc = 0;
4401 unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
4403 for (i = 0; i < pages_per_huge_page; i++) {
4404 if (allow_pagefault)
4405 page_kaddr = kmap(dst_page + i);
4407 page_kaddr = kmap_atomic(dst_page + i);
4408 rc = copy_from_user(page_kaddr,
4409 (const void __user *)(src + i * PAGE_SIZE),
4411 if (allow_pagefault)
4412 kunmap(dst_page + i);
4414 kunmap_atomic(page_kaddr);
4416 ret_val -= (PAGE_SIZE - rc);
4424 #endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4426 #if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4428 static struct kmem_cache *page_ptl_cachep;
4430 void __init ptlock_cache_init(void)
4432 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
4436 bool ptlock_alloc(struct page *page)
4440 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4447 void ptlock_free(struct page *page)
4449 kmem_cache_free(page_ptl_cachep, page->ptl);