4 * Copyright (C) 2008 ARM Limited
5 * Written by Catalin Marinas <catalin.marinas@arm.com>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21 * For more information on the algorithm and kmemleak usage, please see
22 * Documentation/kmemleak.txt.
27 * The following locks and mutexes are used by kmemleak:
29 * - kmemleak_lock (rwlock): protects the object_list modifications and
30 * accesses to the object_tree_root. The object_list is the main list
31 * holding the metadata (struct kmemleak_object) for the allocated memory
32 * blocks. The object_tree_root is a red black tree used to look-up
33 * metadata based on a pointer to the corresponding memory block. The
34 * kmemleak_object structures are added to the object_list and
35 * object_tree_root in the create_object() function called from the
36 * kmemleak_alloc() callback and removed in delete_object() called from the
37 * kmemleak_free() callback
38 * - kmemleak_object.lock (spinlock): protects a kmemleak_object. Accesses to
39 * the metadata (e.g. count) are protected by this lock. Note that some
40 * members of this structure may be protected by other means (atomic or
41 * kmemleak_lock). This lock is also held when scanning the corresponding
42 * memory block to avoid the kernel freeing it via the kmemleak_free()
43 * callback. This is less heavyweight than holding a global lock like
44 * kmemleak_lock during scanning
45 * - scan_mutex (mutex): ensures that only one thread may scan the memory for
46 * unreferenced objects at a time. The gray_list contains the objects which
47 * are already referenced or marked as false positives and need to be
48 * scanned. This list is only modified during a scanning episode when the
49 * scan_mutex is held. At the end of a scan, the gray_list is always empty.
50 * Note that the kmemleak_object.use_count is incremented when an object is
51 * added to the gray_list and therefore cannot be freed. This mutex also
52 * prevents multiple users of the "kmemleak" debugfs file together with
53 * modifications to the memory scanning parameters including the scan_thread
56 * Locks and mutexes are acquired/nested in the following order:
58 * scan_mutex [-> object->lock] -> kmemleak_lock -> other_object->lock (SINGLE_DEPTH_NESTING)
60 * No kmemleak_lock and object->lock nesting is allowed outside scan_mutex
63 * The kmemleak_object structures have a use_count incremented or decremented
64 * using the get_object()/put_object() functions. When the use_count becomes
65 * 0, this count can no longer be incremented and put_object() schedules the
66 * kmemleak_object freeing via an RCU callback. All calls to the get_object()
67 * function must be protected by rcu_read_lock() to avoid accessing a freed
71 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
73 #include <linux/init.h>
74 #include <linux/kernel.h>
75 #include <linux/list.h>
76 #include <linux/sched.h>
77 #include <linux/jiffies.h>
78 #include <linux/delay.h>
79 #include <linux/export.h>
80 #include <linux/kthread.h>
81 #include <linux/rbtree.h>
83 #include <linux/debugfs.h>
84 #include <linux/seq_file.h>
85 #include <linux/cpumask.h>
86 #include <linux/spinlock.h>
87 #include <linux/mutex.h>
88 #include <linux/rcupdate.h>
89 #include <linux/stacktrace.h>
90 #include <linux/cache.h>
91 #include <linux/percpu.h>
92 #include <linux/hardirq.h>
93 #include <linux/bootmem.h>
94 #include <linux/pfn.h>
95 #include <linux/mmzone.h>
96 #include <linux/slab.h>
97 #include <linux/thread_info.h>
98 #include <linux/err.h>
99 #include <linux/uaccess.h>
100 #include <linux/string.h>
101 #include <linux/nodemask.h>
102 #include <linux/mm.h>
103 #include <linux/workqueue.h>
104 #include <linux/crc32.h>
106 #include <asm/sections.h>
107 #include <asm/processor.h>
108 #include <linux/atomic.h>
110 #include <linux/kasan.h>
111 #include <linux/kmemcheck.h>
112 #include <linux/kmemleak.h>
113 #include <linux/memory_hotplug.h>
116 * Kmemleak configuration and common defines.
118 #define MAX_TRACE 16 /* stack trace length */
119 #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
120 #define SECS_FIRST_SCAN 60 /* delay before the first scan */
121 #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
122 #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
124 #define BYTES_PER_POINTER sizeof(void *)
126 /* GFP bitmask for kmemleak internal allocations */
127 #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
128 __GFP_NORETRY | __GFP_NOMEMALLOC | \
131 /* scanning area inside a memory block */
132 struct kmemleak_scan_area {
133 struct hlist_node node;
138 #define KMEMLEAK_GREY 0
139 #define KMEMLEAK_BLACK -1
142 * Structure holding the metadata for each allocated memory block.
143 * Modifications to such objects should be made while holding the
144 * object->lock. Insertions or deletions from object_list, gray_list or
145 * rb_node are already protected by the corresponding locks or mutex (see
146 * the notes on locking above). These objects are reference-counted
147 * (use_count) and freed using the RCU mechanism.
149 struct kmemleak_object {
151 unsigned long flags; /* object status flags */
152 struct list_head object_list;
153 struct list_head gray_list;
154 struct rb_node rb_node;
155 struct rcu_head rcu; /* object_list lockless traversal */
156 /* object usage count; object freed when use_count == 0 */
158 unsigned long pointer;
160 /* minimum number of a pointers found before it is considered leak */
162 /* the total number of pointers found pointing to this object */
164 /* checksum for detecting modified objects */
166 /* memory ranges to be scanned inside an object (empty for all) */
167 struct hlist_head area_list;
168 unsigned long trace[MAX_TRACE];
169 unsigned int trace_len;
170 unsigned long jiffies; /* creation timestamp */
171 pid_t pid; /* pid of the current task */
172 char comm[TASK_COMM_LEN]; /* executable name */
175 /* flag representing the memory block allocation status */
176 #define OBJECT_ALLOCATED (1 << 0)
177 /* flag set after the first reporting of an unreference object */
178 #define OBJECT_REPORTED (1 << 1)
179 /* flag set to not scan the object */
180 #define OBJECT_NO_SCAN (1 << 2)
182 /* number of bytes to print per line; must be 16 or 32 */
183 #define HEX_ROW_SIZE 16
184 /* number of bytes to print at a time (1, 2, 4, 8) */
185 #define HEX_GROUP_SIZE 1
186 /* include ASCII after the hex output */
188 /* max number of lines to be printed */
189 #define HEX_MAX_LINES 2
191 /* the list of all allocated objects */
192 static LIST_HEAD(object_list);
193 /* the list of gray-colored objects (see color_gray comment below) */
194 static LIST_HEAD(gray_list);
195 /* search tree for object boundaries */
196 static struct rb_root object_tree_root = RB_ROOT;
197 /* rw_lock protecting the access to object_list and object_tree_root */
198 static DEFINE_RWLOCK(kmemleak_lock);
200 /* allocation caches for kmemleak internal data */
201 static struct kmem_cache *object_cache;
202 static struct kmem_cache *scan_area_cache;
204 /* set if tracing memory operations is enabled */
205 static int kmemleak_enabled;
206 /* same as above but only for the kmemleak_free() callback */
207 static int kmemleak_free_enabled;
208 /* set in the late_initcall if there were no errors */
209 static int kmemleak_initialized;
210 /* enables or disables early logging of the memory operations */
211 static int kmemleak_early_log = 1;
212 /* set if a kmemleak warning was issued */
213 static int kmemleak_warning;
214 /* set if a fatal kmemleak error has occurred */
215 static int kmemleak_error;
217 /* minimum and maximum address that may be valid pointers */
218 static unsigned long min_addr = ULONG_MAX;
219 static unsigned long max_addr;
221 static struct task_struct *scan_thread;
222 /* used to avoid reporting of recently allocated objects */
223 static unsigned long jiffies_min_age;
224 static unsigned long jiffies_last_scan;
225 /* delay between automatic memory scannings */
226 static signed long jiffies_scan_wait;
227 /* enables or disables the task stacks scanning */
228 static int kmemleak_stack_scan = 1;
229 /* protects the memory scanning, parameters and debug/kmemleak file access */
230 static DEFINE_MUTEX(scan_mutex);
231 /* setting kmemleak=on, will set this var, skipping the disable */
232 static int kmemleak_skip_disable;
233 /* If there are leaks that can be reported */
234 static bool kmemleak_found_leaks;
237 * Early object allocation/freeing logging. Kmemleak is initialized after the
238 * kernel allocator. However, both the kernel allocator and kmemleak may
239 * allocate memory blocks which need to be tracked. Kmemleak defines an
240 * arbitrary buffer to hold the allocation/freeing information before it is
244 /* kmemleak operation type for early logging */
247 KMEMLEAK_ALLOC_PERCPU,
250 KMEMLEAK_FREE_PERCPU,
258 * Structure holding the information passed to kmemleak callbacks during the
262 int op_type; /* kmemleak operation type */
263 const void *ptr; /* allocated/freed memory block */
264 size_t size; /* memory block size */
265 int min_count; /* minimum reference count */
266 unsigned long trace[MAX_TRACE]; /* stack trace */
267 unsigned int trace_len; /* stack trace length */
270 /* early logging buffer and current position */
271 static struct early_log
272 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
273 static int crt_early_log __initdata;
275 static void kmemleak_disable(void);
278 * Print a warning and dump the stack trace.
280 #define kmemleak_warn(x...) do { \
283 kmemleak_warning = 1; \
287 * Macro invoked when a serious kmemleak condition occurred and cannot be
288 * recovered from. Kmemleak will be disabled and further allocation/freeing
289 * tracing no longer available.
291 #define kmemleak_stop(x...) do { \
293 kmemleak_disable(); \
297 * Printing of the objects hex dump to the seq file. The number of lines to be
298 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
299 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
300 * with the object->lock held.
302 static void hex_dump_object(struct seq_file *seq,
303 struct kmemleak_object *object)
305 const u8 *ptr = (const u8 *)object->pointer;
308 /* limit the number of lines to HEX_MAX_LINES */
309 len = min_t(size_t, object->size, HEX_MAX_LINES * HEX_ROW_SIZE);
311 seq_printf(seq, " hex dump (first %zu bytes):\n", len);
312 kasan_disable_current();
313 seq_hex_dump(seq, " ", DUMP_PREFIX_NONE, HEX_ROW_SIZE,
314 HEX_GROUP_SIZE, ptr, len, HEX_ASCII);
315 kasan_enable_current();
319 * Object colors, encoded with count and min_count:
320 * - white - orphan object, not enough references to it (count < min_count)
321 * - gray - not orphan, not marked as false positive (min_count == 0) or
322 * sufficient references to it (count >= min_count)
323 * - black - ignore, it doesn't contain references (e.g. text section)
324 * (min_count == -1). No function defined for this color.
325 * Newly created objects don't have any color assigned (object->count == -1)
326 * before the next memory scan when they become white.
328 static bool color_white(const struct kmemleak_object *object)
330 return object->count != KMEMLEAK_BLACK &&
331 object->count < object->min_count;
334 static bool color_gray(const struct kmemleak_object *object)
336 return object->min_count != KMEMLEAK_BLACK &&
337 object->count >= object->min_count;
341 * Objects are considered unreferenced only if their color is white, they have
342 * not be deleted and have a minimum age to avoid false positives caused by
343 * pointers temporarily stored in CPU registers.
345 static bool unreferenced_object(struct kmemleak_object *object)
347 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
348 time_before_eq(object->jiffies + jiffies_min_age,
353 * Printing of the unreferenced objects information to the seq file. The
354 * print_unreferenced function must be called with the object->lock held.
356 static void print_unreferenced(struct seq_file *seq,
357 struct kmemleak_object *object)
360 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
362 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
363 object->pointer, object->size);
364 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
365 object->comm, object->pid, object->jiffies,
366 msecs_age / 1000, msecs_age % 1000);
367 hex_dump_object(seq, object);
368 seq_printf(seq, " backtrace:\n");
370 for (i = 0; i < object->trace_len; i++) {
371 void *ptr = (void *)object->trace[i];
372 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
377 * Print the kmemleak_object information. This function is used mainly for
378 * debugging special cases when kmemleak operations. It must be called with
379 * the object->lock held.
381 static void dump_object_info(struct kmemleak_object *object)
383 struct stack_trace trace;
385 trace.nr_entries = object->trace_len;
386 trace.entries = object->trace;
388 pr_notice("Object 0x%08lx (size %zu):\n",
389 object->pointer, object->size);
390 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
391 object->comm, object->pid, object->jiffies);
392 pr_notice(" min_count = %d\n", object->min_count);
393 pr_notice(" count = %d\n", object->count);
394 pr_notice(" flags = 0x%lx\n", object->flags);
395 pr_notice(" checksum = %u\n", object->checksum);
396 pr_notice(" backtrace:\n");
397 print_stack_trace(&trace, 4);
401 * Look-up a memory block metadata (kmemleak_object) in the object search
402 * tree based on a pointer value. If alias is 0, only values pointing to the
403 * beginning of the memory block are allowed. The kmemleak_lock must be held
404 * when calling this function.
406 static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
408 struct rb_node *rb = object_tree_root.rb_node;
411 struct kmemleak_object *object =
412 rb_entry(rb, struct kmemleak_object, rb_node);
413 if (ptr < object->pointer)
414 rb = object->rb_node.rb_left;
415 else if (object->pointer + object->size <= ptr)
416 rb = object->rb_node.rb_right;
417 else if (object->pointer == ptr || alias)
420 kmemleak_warn("Found object by alias at 0x%08lx\n",
422 dump_object_info(object);
430 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
431 * that once an object's use_count reached 0, the RCU freeing was already
432 * registered and the object should no longer be used. This function must be
433 * called under the protection of rcu_read_lock().
435 static int get_object(struct kmemleak_object *object)
437 return atomic_inc_not_zero(&object->use_count);
441 * RCU callback to free a kmemleak_object.
443 static void free_object_rcu(struct rcu_head *rcu)
445 struct hlist_node *tmp;
446 struct kmemleak_scan_area *area;
447 struct kmemleak_object *object =
448 container_of(rcu, struct kmemleak_object, rcu);
451 * Once use_count is 0 (guaranteed by put_object), there is no other
452 * code accessing this object, hence no need for locking.
454 hlist_for_each_entry_safe(area, tmp, &object->area_list, node) {
455 hlist_del(&area->node);
456 kmem_cache_free(scan_area_cache, area);
458 kmem_cache_free(object_cache, object);
462 * Decrement the object use_count. Once the count is 0, free the object using
463 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
464 * delete_object() path, the delayed RCU freeing ensures that there is no
465 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
468 static void put_object(struct kmemleak_object *object)
470 if (!atomic_dec_and_test(&object->use_count))
473 /* should only get here after delete_object was called */
474 WARN_ON(object->flags & OBJECT_ALLOCATED);
476 call_rcu(&object->rcu, free_object_rcu);
480 * Look up an object in the object search tree and increase its use_count.
482 static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
485 struct kmemleak_object *object;
488 read_lock_irqsave(&kmemleak_lock, flags);
489 object = lookup_object(ptr, alias);
490 read_unlock_irqrestore(&kmemleak_lock, flags);
492 /* check whether the object is still available */
493 if (object && !get_object(object))
501 * Look up an object in the object search tree and remove it from both
502 * object_tree_root and object_list. The returned object's use_count should be
503 * at least 1, as initially set by create_object().
505 static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int alias)
508 struct kmemleak_object *object;
510 write_lock_irqsave(&kmemleak_lock, flags);
511 object = lookup_object(ptr, alias);
513 rb_erase(&object->rb_node, &object_tree_root);
514 list_del_rcu(&object->object_list);
516 write_unlock_irqrestore(&kmemleak_lock, flags);
522 * Save stack trace to the given array of MAX_TRACE size.
524 static int __save_stack_trace(unsigned long *trace)
526 struct stack_trace stack_trace;
528 stack_trace.max_entries = MAX_TRACE;
529 stack_trace.nr_entries = 0;
530 stack_trace.entries = trace;
531 stack_trace.skip = 2;
532 save_stack_trace(&stack_trace);
534 return stack_trace.nr_entries;
538 * Create the metadata (struct kmemleak_object) corresponding to an allocated
539 * memory block and add it to the object_list and object_tree_root.
541 static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
542 int min_count, gfp_t gfp)
545 struct kmemleak_object *object, *parent;
546 struct rb_node **link, *rb_parent;
548 object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
550 pr_warn("Cannot allocate a kmemleak_object structure\n");
555 INIT_LIST_HEAD(&object->object_list);
556 INIT_LIST_HEAD(&object->gray_list);
557 INIT_HLIST_HEAD(&object->area_list);
558 spin_lock_init(&object->lock);
559 atomic_set(&object->use_count, 1);
560 object->flags = OBJECT_ALLOCATED;
561 object->pointer = ptr;
563 object->min_count = min_count;
564 object->count = 0; /* white color initially */
565 object->jiffies = jiffies;
566 object->checksum = 0;
568 /* task information */
571 strncpy(object->comm, "hardirq", sizeof(object->comm));
572 } else if (in_softirq()) {
574 strncpy(object->comm, "softirq", sizeof(object->comm));
576 object->pid = current->pid;
578 * There is a small chance of a race with set_task_comm(),
579 * however using get_task_comm() here may cause locking
580 * dependency issues with current->alloc_lock. In the worst
581 * case, the command line is not correct.
583 strncpy(object->comm, current->comm, sizeof(object->comm));
586 /* kernel backtrace */
587 object->trace_len = __save_stack_trace(object->trace);
589 write_lock_irqsave(&kmemleak_lock, flags);
591 min_addr = min(min_addr, ptr);
592 max_addr = max(max_addr, ptr + size);
593 link = &object_tree_root.rb_node;
597 parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
598 if (ptr + size <= parent->pointer)
599 link = &parent->rb_node.rb_left;
600 else if (parent->pointer + parent->size <= ptr)
601 link = &parent->rb_node.rb_right;
603 kmemleak_stop("Cannot insert 0x%lx into the object search tree (overlaps existing)\n",
606 * No need for parent->lock here since "parent" cannot
607 * be freed while the kmemleak_lock is held.
609 dump_object_info(parent);
610 kmem_cache_free(object_cache, object);
615 rb_link_node(&object->rb_node, rb_parent, link);
616 rb_insert_color(&object->rb_node, &object_tree_root);
618 list_add_tail_rcu(&object->object_list, &object_list);
620 write_unlock_irqrestore(&kmemleak_lock, flags);
625 * Mark the object as not allocated and schedule RCU freeing via put_object().
627 static void __delete_object(struct kmemleak_object *object)
631 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
632 WARN_ON(atomic_read(&object->use_count) < 1);
635 * Locking here also ensures that the corresponding memory block
636 * cannot be freed when it is being scanned.
638 spin_lock_irqsave(&object->lock, flags);
639 object->flags &= ~OBJECT_ALLOCATED;
640 spin_unlock_irqrestore(&object->lock, flags);
645 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
648 static void delete_object_full(unsigned long ptr)
650 struct kmemleak_object *object;
652 object = find_and_remove_object(ptr, 0);
655 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
660 __delete_object(object);
664 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
665 * delete it. If the memory block is partially freed, the function may create
666 * additional metadata for the remaining parts of the block.
668 static void delete_object_part(unsigned long ptr, size_t size)
670 struct kmemleak_object *object;
671 unsigned long start, end;
673 object = find_and_remove_object(ptr, 1);
676 kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n",
683 * Create one or two objects that may result from the memory block
684 * split. Note that partial freeing is only done by free_bootmem() and
685 * this happens before kmemleak_init() is called. The path below is
686 * only executed during early log recording in kmemleak_init(), so
687 * GFP_KERNEL is enough.
689 start = object->pointer;
690 end = object->pointer + object->size;
692 create_object(start, ptr - start, object->min_count,
694 if (ptr + size < end)
695 create_object(ptr + size, end - ptr - size, object->min_count,
698 __delete_object(object);
701 static void __paint_it(struct kmemleak_object *object, int color)
703 object->min_count = color;
704 if (color == KMEMLEAK_BLACK)
705 object->flags |= OBJECT_NO_SCAN;
708 static void paint_it(struct kmemleak_object *object, int color)
712 spin_lock_irqsave(&object->lock, flags);
713 __paint_it(object, color);
714 spin_unlock_irqrestore(&object->lock, flags);
717 static void paint_ptr(unsigned long ptr, int color)
719 struct kmemleak_object *object;
721 object = find_and_get_object(ptr, 0);
723 kmemleak_warn("Trying to color unknown object at 0x%08lx as %s\n",
725 (color == KMEMLEAK_GREY) ? "Grey" :
726 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
729 paint_it(object, color);
734 * Mark an object permanently as gray-colored so that it can no longer be
735 * reported as a leak. This is used in general to mark a false positive.
737 static void make_gray_object(unsigned long ptr)
739 paint_ptr(ptr, KMEMLEAK_GREY);
743 * Mark the object as black-colored so that it is ignored from scans and
746 static void make_black_object(unsigned long ptr)
748 paint_ptr(ptr, KMEMLEAK_BLACK);
752 * Add a scanning area to the object. If at least one such area is added,
753 * kmemleak will only scan these ranges rather than the whole memory block.
755 static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
758 struct kmemleak_object *object;
759 struct kmemleak_scan_area *area;
761 object = find_and_get_object(ptr, 1);
763 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
768 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
770 pr_warn("Cannot allocate a scan area\n");
774 spin_lock_irqsave(&object->lock, flags);
775 if (size == SIZE_MAX) {
776 size = object->pointer + object->size - ptr;
777 } else if (ptr + size > object->pointer + object->size) {
778 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
779 dump_object_info(object);
780 kmem_cache_free(scan_area_cache, area);
784 INIT_HLIST_NODE(&area->node);
788 hlist_add_head(&area->node, &object->area_list);
790 spin_unlock_irqrestore(&object->lock, flags);
796 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
797 * pointer. Such object will not be scanned by kmemleak but references to it
800 static void object_no_scan(unsigned long ptr)
803 struct kmemleak_object *object;
805 object = find_and_get_object(ptr, 0);
807 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
811 spin_lock_irqsave(&object->lock, flags);
812 object->flags |= OBJECT_NO_SCAN;
813 spin_unlock_irqrestore(&object->lock, flags);
818 * Log an early kmemleak_* call to the early_log buffer. These calls will be
819 * processed later once kmemleak is fully initialized.
821 static void __init log_early(int op_type, const void *ptr, size_t size,
825 struct early_log *log;
827 if (kmemleak_error) {
828 /* kmemleak stopped recording, just count the requests */
833 if (crt_early_log >= ARRAY_SIZE(early_log)) {
840 * There is no need for locking since the kernel is still in UP mode
841 * at this stage. Disabling the IRQs is enough.
843 local_irq_save(flags);
844 log = &early_log[crt_early_log];
845 log->op_type = op_type;
848 log->min_count = min_count;
849 log->trace_len = __save_stack_trace(log->trace);
851 local_irq_restore(flags);
855 * Log an early allocated block and populate the stack trace.
857 static void early_alloc(struct early_log *log)
859 struct kmemleak_object *object;
863 if (!kmemleak_enabled || !log->ptr || IS_ERR(log->ptr))
867 * RCU locking needed to ensure object is not freed via put_object().
870 object = create_object((unsigned long)log->ptr, log->size,
871 log->min_count, GFP_ATOMIC);
874 spin_lock_irqsave(&object->lock, flags);
875 for (i = 0; i < log->trace_len; i++)
876 object->trace[i] = log->trace[i];
877 object->trace_len = log->trace_len;
878 spin_unlock_irqrestore(&object->lock, flags);
884 * Log an early allocated block and populate the stack trace.
886 static void early_alloc_percpu(struct early_log *log)
889 const void __percpu *ptr = log->ptr;
891 for_each_possible_cpu(cpu) {
892 log->ptr = per_cpu_ptr(ptr, cpu);
898 * kmemleak_alloc - register a newly allocated object
899 * @ptr: pointer to beginning of the object
900 * @size: size of the object
901 * @min_count: minimum number of references to this object. If during memory
902 * scanning a number of references less than @min_count is found,
903 * the object is reported as a memory leak. If @min_count is 0,
904 * the object is never reported as a leak. If @min_count is -1,
905 * the object is ignored (not scanned and not reported as a leak)
906 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
908 * This function is called from the kernel allocators when a new object
909 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
911 void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
914 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
916 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
917 create_object((unsigned long)ptr, size, min_count, gfp);
918 else if (kmemleak_early_log)
919 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
921 EXPORT_SYMBOL_GPL(kmemleak_alloc);
924 * kmemleak_alloc_percpu - register a newly allocated __percpu object
925 * @ptr: __percpu pointer to beginning of the object
926 * @size: size of the object
927 * @gfp: flags used for kmemleak internal memory allocations
929 * This function is called from the kernel percpu allocator when a new object
930 * (memory block) is allocated (alloc_percpu).
932 void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size,
937 pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
940 * Percpu allocations are only scanned and not reported as leaks
941 * (min_count is set to 0).
943 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
944 for_each_possible_cpu(cpu)
945 create_object((unsigned long)per_cpu_ptr(ptr, cpu),
947 else if (kmemleak_early_log)
948 log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
950 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
953 * kmemleak_free - unregister a previously registered object
954 * @ptr: pointer to beginning of the object
956 * This function is called from the kernel allocators when an object (memory
957 * block) is freed (kmem_cache_free, kfree, vfree etc.).
959 void __ref kmemleak_free(const void *ptr)
961 pr_debug("%s(0x%p)\n", __func__, ptr);
963 if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
964 delete_object_full((unsigned long)ptr);
965 else if (kmemleak_early_log)
966 log_early(KMEMLEAK_FREE, ptr, 0, 0);
968 EXPORT_SYMBOL_GPL(kmemleak_free);
971 * kmemleak_free_part - partially unregister a previously registered object
972 * @ptr: pointer to the beginning or inside the object. This also
973 * represents the start of the range to be freed
974 * @size: size to be unregistered
976 * This function is called when only a part of a memory block is freed
977 * (usually from the bootmem allocator).
979 void __ref kmemleak_free_part(const void *ptr, size_t size)
981 pr_debug("%s(0x%p)\n", __func__, ptr);
983 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
984 delete_object_part((unsigned long)ptr, size);
985 else if (kmemleak_early_log)
986 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
988 EXPORT_SYMBOL_GPL(kmemleak_free_part);
991 * kmemleak_free_percpu - unregister a previously registered __percpu object
992 * @ptr: __percpu pointer to beginning of the object
994 * This function is called from the kernel percpu allocator when an object
995 * (memory block) is freed (free_percpu).
997 void __ref kmemleak_free_percpu(const void __percpu *ptr)
1001 pr_debug("%s(0x%p)\n", __func__, ptr);
1003 if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
1004 for_each_possible_cpu(cpu)
1005 delete_object_full((unsigned long)per_cpu_ptr(ptr,
1007 else if (kmemleak_early_log)
1008 log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
1010 EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
1013 * kmemleak_update_trace - update object allocation stack trace
1014 * @ptr: pointer to beginning of the object
1016 * Override the object allocation stack trace for cases where the actual
1017 * allocation place is not always useful.
1019 void __ref kmemleak_update_trace(const void *ptr)
1021 struct kmemleak_object *object;
1022 unsigned long flags;
1024 pr_debug("%s(0x%p)\n", __func__, ptr);
1026 if (!kmemleak_enabled || IS_ERR_OR_NULL(ptr))
1029 object = find_and_get_object((unsigned long)ptr, 1);
1032 kmemleak_warn("Updating stack trace for unknown object at %p\n",
1038 spin_lock_irqsave(&object->lock, flags);
1039 object->trace_len = __save_stack_trace(object->trace);
1040 spin_unlock_irqrestore(&object->lock, flags);
1044 EXPORT_SYMBOL(kmemleak_update_trace);
1047 * kmemleak_not_leak - mark an allocated object as false positive
1048 * @ptr: pointer to beginning of the object
1050 * Calling this function on an object will cause the memory block to no longer
1051 * be reported as leak and always be scanned.
1053 void __ref kmemleak_not_leak(const void *ptr)
1055 pr_debug("%s(0x%p)\n", __func__, ptr);
1057 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1058 make_gray_object((unsigned long)ptr);
1059 else if (kmemleak_early_log)
1060 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
1062 EXPORT_SYMBOL(kmemleak_not_leak);
1065 * kmemleak_ignore - ignore an allocated object
1066 * @ptr: pointer to beginning of the object
1068 * Calling this function on an object will cause the memory block to be
1069 * ignored (not scanned and not reported as a leak). This is usually done when
1070 * it is known that the corresponding block is not a leak and does not contain
1071 * any references to other allocated memory blocks.
1073 void __ref kmemleak_ignore(const void *ptr)
1075 pr_debug("%s(0x%p)\n", __func__, ptr);
1077 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1078 make_black_object((unsigned long)ptr);
1079 else if (kmemleak_early_log)
1080 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
1082 EXPORT_SYMBOL(kmemleak_ignore);
1085 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1086 * @ptr: pointer to beginning or inside the object. This also
1087 * represents the start of the scan area
1088 * @size: size of the scan area
1089 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1091 * This function is used when it is known that only certain parts of an object
1092 * contain references to other objects. Kmemleak will only scan these areas
1093 * reducing the number false negatives.
1095 void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
1097 pr_debug("%s(0x%p)\n", __func__, ptr);
1099 if (kmemleak_enabled && ptr && size && !IS_ERR(ptr))
1100 add_scan_area((unsigned long)ptr, size, gfp);
1101 else if (kmemleak_early_log)
1102 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
1104 EXPORT_SYMBOL(kmemleak_scan_area);
1107 * kmemleak_no_scan - do not scan an allocated object
1108 * @ptr: pointer to beginning of the object
1110 * This function notifies kmemleak not to scan the given memory block. Useful
1111 * in situations where it is known that the given object does not contain any
1112 * references to other objects. Kmemleak will not scan such objects reducing
1113 * the number of false negatives.
1115 void __ref kmemleak_no_scan(const void *ptr)
1117 pr_debug("%s(0x%p)\n", __func__, ptr);
1119 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1120 object_no_scan((unsigned long)ptr);
1121 else if (kmemleak_early_log)
1122 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
1124 EXPORT_SYMBOL(kmemleak_no_scan);
1127 * kmemleak_alloc_phys - similar to kmemleak_alloc but taking a physical
1130 void __ref kmemleak_alloc_phys(phys_addr_t phys, size_t size, int min_count,
1133 if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1134 kmemleak_alloc(__va(phys), size, min_count, gfp);
1136 EXPORT_SYMBOL(kmemleak_alloc_phys);
1139 * kmemleak_free_part_phys - similar to kmemleak_free_part but taking a
1140 * physical address argument
1142 void __ref kmemleak_free_part_phys(phys_addr_t phys, size_t size)
1144 if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1145 kmemleak_free_part(__va(phys), size);
1147 EXPORT_SYMBOL(kmemleak_free_part_phys);
1150 * kmemleak_not_leak_phys - similar to kmemleak_not_leak but taking a physical
1153 void __ref kmemleak_not_leak_phys(phys_addr_t phys)
1155 if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1156 kmemleak_not_leak(__va(phys));
1158 EXPORT_SYMBOL(kmemleak_not_leak_phys);
1161 * kmemleak_ignore_phys - similar to kmemleak_ignore but taking a physical
1164 void __ref kmemleak_ignore_phys(phys_addr_t phys)
1166 if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1167 kmemleak_ignore(__va(phys));
1169 EXPORT_SYMBOL(kmemleak_ignore_phys);
1172 * Update an object's checksum and return true if it was modified.
1174 static bool update_checksum(struct kmemleak_object *object)
1176 u32 old_csum = object->checksum;
1178 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
1181 kasan_disable_current();
1182 object->checksum = crc32(0, (void *)object->pointer, object->size);
1183 kasan_enable_current();
1185 return object->checksum != old_csum;
1189 * Memory scanning is a long process and it needs to be interruptable. This
1190 * function checks whether such interrupt condition occurred.
1192 static int scan_should_stop(void)
1194 if (!kmemleak_enabled)
1198 * This function may be called from either process or kthread context,
1199 * hence the need to check for both stop conditions.
1202 return signal_pending(current);
1204 return kthread_should_stop();
1210 * Scan a memory block (exclusive range) for valid pointers and add those
1211 * found to the gray list.
1213 static void scan_block(void *_start, void *_end,
1214 struct kmemleak_object *scanned)
1217 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1218 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1219 unsigned long flags;
1221 read_lock_irqsave(&kmemleak_lock, flags);
1222 for (ptr = start; ptr < end; ptr++) {
1223 struct kmemleak_object *object;
1224 unsigned long pointer;
1226 if (scan_should_stop())
1229 /* don't scan uninitialized memory */
1230 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1234 kasan_disable_current();
1236 kasan_enable_current();
1238 if (pointer < min_addr || pointer >= max_addr)
1242 * No need for get_object() here since we hold kmemleak_lock.
1243 * object->use_count cannot be dropped to 0 while the object
1244 * is still present in object_tree_root and object_list
1245 * (with updates protected by kmemleak_lock).
1247 object = lookup_object(pointer, 1);
1250 if (object == scanned)
1251 /* self referenced, ignore */
1255 * Avoid the lockdep recursive warning on object->lock being
1256 * previously acquired in scan_object(). These locks are
1257 * enclosed by scan_mutex.
1259 spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
1260 if (!color_white(object)) {
1261 /* non-orphan, ignored or new */
1262 spin_unlock(&object->lock);
1267 * Increase the object's reference count (number of pointers
1268 * to the memory block). If this count reaches the required
1269 * minimum, the object's color will become gray and it will be
1270 * added to the gray_list.
1273 if (color_gray(object)) {
1274 /* put_object() called when removing from gray_list */
1275 WARN_ON(!get_object(object));
1276 list_add_tail(&object->gray_list, &gray_list);
1278 spin_unlock(&object->lock);
1280 read_unlock_irqrestore(&kmemleak_lock, flags);
1284 * Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency.
1286 static void scan_large_block(void *start, void *end)
1290 while (start < end) {
1291 next = min(start + MAX_SCAN_SIZE, end);
1292 scan_block(start, next, NULL);
1299 * Scan a memory block corresponding to a kmemleak_object. A condition is
1300 * that object->use_count >= 1.
1302 static void scan_object(struct kmemleak_object *object)
1304 struct kmemleak_scan_area *area;
1305 unsigned long flags;
1308 * Once the object->lock is acquired, the corresponding memory block
1309 * cannot be freed (the same lock is acquired in delete_object).
1311 spin_lock_irqsave(&object->lock, flags);
1312 if (object->flags & OBJECT_NO_SCAN)
1314 if (!(object->flags & OBJECT_ALLOCATED))
1315 /* already freed object */
1317 if (hlist_empty(&object->area_list)) {
1318 void *start = (void *)object->pointer;
1319 void *end = (void *)(object->pointer + object->size);
1323 next = min(start + MAX_SCAN_SIZE, end);
1324 scan_block(start, next, object);
1330 spin_unlock_irqrestore(&object->lock, flags);
1332 spin_lock_irqsave(&object->lock, flags);
1333 } while (object->flags & OBJECT_ALLOCATED);
1335 hlist_for_each_entry(area, &object->area_list, node)
1336 scan_block((void *)area->start,
1337 (void *)(area->start + area->size),
1340 spin_unlock_irqrestore(&object->lock, flags);
1344 * Scan the objects already referenced (gray objects). More objects will be
1345 * referenced and, if there are no memory leaks, all the objects are scanned.
1347 static void scan_gray_list(void)
1349 struct kmemleak_object *object, *tmp;
1352 * The list traversal is safe for both tail additions and removals
1353 * from inside the loop. The kmemleak objects cannot be freed from
1354 * outside the loop because their use_count was incremented.
1356 object = list_entry(gray_list.next, typeof(*object), gray_list);
1357 while (&object->gray_list != &gray_list) {
1360 /* may add new objects to the list */
1361 if (!scan_should_stop())
1362 scan_object(object);
1364 tmp = list_entry(object->gray_list.next, typeof(*object),
1367 /* remove the object from the list and release it */
1368 list_del(&object->gray_list);
1373 WARN_ON(!list_empty(&gray_list));
1377 * Scan data sections and all the referenced memory blocks allocated via the
1378 * kernel's standard allocators. This function must be called with the
1381 static void kmemleak_scan(void)
1383 unsigned long flags;
1384 struct kmemleak_object *object;
1388 jiffies_last_scan = jiffies;
1390 /* prepare the kmemleak_object's */
1392 list_for_each_entry_rcu(object, &object_list, object_list) {
1393 spin_lock_irqsave(&object->lock, flags);
1396 * With a few exceptions there should be a maximum of
1397 * 1 reference to any object at this point.
1399 if (atomic_read(&object->use_count) > 1) {
1400 pr_debug("object->use_count = %d\n",
1401 atomic_read(&object->use_count));
1402 dump_object_info(object);
1405 /* reset the reference count (whiten the object) */
1407 if (color_gray(object) && get_object(object))
1408 list_add_tail(&object->gray_list, &gray_list);
1410 spin_unlock_irqrestore(&object->lock, flags);
1414 /* data/bss scanning */
1415 scan_large_block(_sdata, _edata);
1416 scan_large_block(__bss_start, __bss_stop);
1417 scan_large_block(__start_data_ro_after_init, __end_data_ro_after_init);
1420 /* per-cpu sections scanning */
1421 for_each_possible_cpu(i)
1422 scan_large_block(__per_cpu_start + per_cpu_offset(i),
1423 __per_cpu_end + per_cpu_offset(i));
1427 * Struct page scanning for each node.
1430 for_each_online_node(i) {
1431 unsigned long start_pfn = node_start_pfn(i);
1432 unsigned long end_pfn = node_end_pfn(i);
1435 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1438 if (!pfn_valid(pfn))
1440 page = pfn_to_page(pfn);
1441 /* only scan if page is in use */
1442 if (page_count(page) == 0)
1444 scan_block(page, page + 1, NULL);
1450 * Scanning the task stacks (may introduce false negatives).
1452 if (kmemleak_stack_scan) {
1453 struct task_struct *p, *g;
1455 read_lock(&tasklist_lock);
1456 do_each_thread(g, p) {
1457 void *stack = try_get_task_stack(p);
1459 scan_block(stack, stack + THREAD_SIZE, NULL);
1462 } while_each_thread(g, p);
1463 read_unlock(&tasklist_lock);
1467 * Scan the objects already referenced from the sections scanned
1473 * Check for new or unreferenced objects modified since the previous
1474 * scan and color them gray until the next scan.
1477 list_for_each_entry_rcu(object, &object_list, object_list) {
1478 spin_lock_irqsave(&object->lock, flags);
1479 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1480 && update_checksum(object) && get_object(object)) {
1481 /* color it gray temporarily */
1482 object->count = object->min_count;
1483 list_add_tail(&object->gray_list, &gray_list);
1485 spin_unlock_irqrestore(&object->lock, flags);
1490 * Re-scan the gray list for modified unreferenced objects.
1495 * If scanning was stopped do not report any new unreferenced objects.
1497 if (scan_should_stop())
1501 * Scanning result reporting.
1504 list_for_each_entry_rcu(object, &object_list, object_list) {
1505 spin_lock_irqsave(&object->lock, flags);
1506 if (unreferenced_object(object) &&
1507 !(object->flags & OBJECT_REPORTED)) {
1508 object->flags |= OBJECT_REPORTED;
1511 spin_unlock_irqrestore(&object->lock, flags);
1516 kmemleak_found_leaks = true;
1518 pr_info("%d new suspected memory leaks (see /sys/kernel/debug/kmemleak)\n",
1525 * Thread function performing automatic memory scanning. Unreferenced objects
1526 * at the end of a memory scan are reported but only the first time.
1528 static int kmemleak_scan_thread(void *arg)
1530 static int first_run = 1;
1532 pr_info("Automatic memory scanning thread started\n");
1533 set_user_nice(current, 10);
1536 * Wait before the first scan to allow the system to fully initialize.
1539 signed long timeout = msecs_to_jiffies(SECS_FIRST_SCAN * 1000);
1541 while (timeout && !kthread_should_stop())
1542 timeout = schedule_timeout_interruptible(timeout);
1545 while (!kthread_should_stop()) {
1546 signed long timeout = jiffies_scan_wait;
1548 mutex_lock(&scan_mutex);
1550 mutex_unlock(&scan_mutex);
1552 /* wait before the next scan */
1553 while (timeout && !kthread_should_stop())
1554 timeout = schedule_timeout_interruptible(timeout);
1557 pr_info("Automatic memory scanning thread ended\n");
1563 * Start the automatic memory scanning thread. This function must be called
1564 * with the scan_mutex held.
1566 static void start_scan_thread(void)
1570 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1571 if (IS_ERR(scan_thread)) {
1572 pr_warn("Failed to create the scan thread\n");
1578 * Stop the automatic memory scanning thread. This function must be called
1579 * with the scan_mutex held.
1581 static void stop_scan_thread(void)
1584 kthread_stop(scan_thread);
1590 * Iterate over the object_list and return the first valid object at or after
1591 * the required position with its use_count incremented. The function triggers
1592 * a memory scanning when the pos argument points to the first position.
1594 static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1596 struct kmemleak_object *object;
1600 err = mutex_lock_interruptible(&scan_mutex);
1602 return ERR_PTR(err);
1605 list_for_each_entry_rcu(object, &object_list, object_list) {
1608 if (get_object(object))
1617 * Return the next object in the object_list. The function decrements the
1618 * use_count of the previous object and increases that of the next one.
1620 static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1622 struct kmemleak_object *prev_obj = v;
1623 struct kmemleak_object *next_obj = NULL;
1624 struct kmemleak_object *obj = prev_obj;
1628 list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
1629 if (get_object(obj)) {
1635 put_object(prev_obj);
1640 * Decrement the use_count of the last object required, if any.
1642 static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1646 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1647 * waiting was interrupted, so only release it if !IS_ERR.
1650 mutex_unlock(&scan_mutex);
1657 * Print the information for an unreferenced object to the seq file.
1659 static int kmemleak_seq_show(struct seq_file *seq, void *v)
1661 struct kmemleak_object *object = v;
1662 unsigned long flags;
1664 spin_lock_irqsave(&object->lock, flags);
1665 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
1666 print_unreferenced(seq, object);
1667 spin_unlock_irqrestore(&object->lock, flags);
1671 static const struct seq_operations kmemleak_seq_ops = {
1672 .start = kmemleak_seq_start,
1673 .next = kmemleak_seq_next,
1674 .stop = kmemleak_seq_stop,
1675 .show = kmemleak_seq_show,
1678 static int kmemleak_open(struct inode *inode, struct file *file)
1680 return seq_open(file, &kmemleak_seq_ops);
1683 static int dump_str_object_info(const char *str)
1685 unsigned long flags;
1686 struct kmemleak_object *object;
1689 if (kstrtoul(str, 0, &addr))
1691 object = find_and_get_object(addr, 0);
1693 pr_info("Unknown object at 0x%08lx\n", addr);
1697 spin_lock_irqsave(&object->lock, flags);
1698 dump_object_info(object);
1699 spin_unlock_irqrestore(&object->lock, flags);
1706 * We use grey instead of black to ensure we can do future scans on the same
1707 * objects. If we did not do future scans these black objects could
1708 * potentially contain references to newly allocated objects in the future and
1709 * we'd end up with false positives.
1711 static void kmemleak_clear(void)
1713 struct kmemleak_object *object;
1714 unsigned long flags;
1717 list_for_each_entry_rcu(object, &object_list, object_list) {
1718 spin_lock_irqsave(&object->lock, flags);
1719 if ((object->flags & OBJECT_REPORTED) &&
1720 unreferenced_object(object))
1721 __paint_it(object, KMEMLEAK_GREY);
1722 spin_unlock_irqrestore(&object->lock, flags);
1726 kmemleak_found_leaks = false;
1729 static void __kmemleak_do_cleanup(void);
1732 * File write operation to configure kmemleak at run-time. The following
1733 * commands can be written to the /sys/kernel/debug/kmemleak file:
1734 * off - disable kmemleak (irreversible)
1735 * stack=on - enable the task stacks scanning
1736 * stack=off - disable the tasks stacks scanning
1737 * scan=on - start the automatic memory scanning thread
1738 * scan=off - stop the automatic memory scanning thread
1739 * scan=... - set the automatic memory scanning period in seconds (0 to
1741 * scan - trigger a memory scan
1742 * clear - mark all current reported unreferenced kmemleak objects as
1743 * grey to ignore printing them, or free all kmemleak objects
1744 * if kmemleak has been disabled.
1745 * dump=... - dump information about the object found at the given address
1747 static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1748 size_t size, loff_t *ppos)
1754 buf_size = min(size, (sizeof(buf) - 1));
1755 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1759 ret = mutex_lock_interruptible(&scan_mutex);
1763 if (strncmp(buf, "clear", 5) == 0) {
1764 if (kmemleak_enabled)
1767 __kmemleak_do_cleanup();
1771 if (!kmemleak_enabled) {
1776 if (strncmp(buf, "off", 3) == 0)
1778 else if (strncmp(buf, "stack=on", 8) == 0)
1779 kmemleak_stack_scan = 1;
1780 else if (strncmp(buf, "stack=off", 9) == 0)
1781 kmemleak_stack_scan = 0;
1782 else if (strncmp(buf, "scan=on", 7) == 0)
1783 start_scan_thread();
1784 else if (strncmp(buf, "scan=off", 8) == 0)
1786 else if (strncmp(buf, "scan=", 5) == 0) {
1789 ret = kstrtoul(buf + 5, 0, &secs);
1794 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1795 start_scan_thread();
1797 } else if (strncmp(buf, "scan", 4) == 0)
1799 else if (strncmp(buf, "dump=", 5) == 0)
1800 ret = dump_str_object_info(buf + 5);
1805 mutex_unlock(&scan_mutex);
1809 /* ignore the rest of the buffer, only one command at a time */
1814 static const struct file_operations kmemleak_fops = {
1815 .owner = THIS_MODULE,
1816 .open = kmemleak_open,
1818 .write = kmemleak_write,
1819 .llseek = seq_lseek,
1820 .release = seq_release,
1823 static void __kmemleak_do_cleanup(void)
1825 struct kmemleak_object *object;
1828 list_for_each_entry_rcu(object, &object_list, object_list)
1829 delete_object_full(object->pointer);
1834 * Stop the memory scanning thread and free the kmemleak internal objects if
1835 * no previous scan thread (otherwise, kmemleak may still have some useful
1836 * information on memory leaks).
1838 static void kmemleak_do_cleanup(struct work_struct *work)
1843 * Once the scan thread has stopped, it is safe to no longer track
1844 * object freeing. Ordering of the scan thread stopping and the memory
1845 * accesses below is guaranteed by the kthread_stop() function.
1847 kmemleak_free_enabled = 0;
1849 if (!kmemleak_found_leaks)
1850 __kmemleak_do_cleanup();
1852 pr_info("Kmemleak disabled without freeing internal data. Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\".\n");
1855 static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
1858 * Disable kmemleak. No memory allocation/freeing will be traced once this
1859 * function is called. Disabling kmemleak is an irreversible operation.
1861 static void kmemleak_disable(void)
1863 /* atomically check whether it was already invoked */
1864 if (cmpxchg(&kmemleak_error, 0, 1))
1867 /* stop any memory operation tracing */
1868 kmemleak_enabled = 0;
1870 /* check whether it is too early for a kernel thread */
1871 if (kmemleak_initialized)
1872 schedule_work(&cleanup_work);
1874 kmemleak_free_enabled = 0;
1876 pr_info("Kernel memory leak detector disabled\n");
1880 * Allow boot-time kmemleak disabling (enabled by default).
1882 static int kmemleak_boot_config(char *str)
1886 if (strcmp(str, "off") == 0)
1888 else if (strcmp(str, "on") == 0)
1889 kmemleak_skip_disable = 1;
1894 early_param("kmemleak", kmemleak_boot_config);
1896 static void __init print_log_trace(struct early_log *log)
1898 struct stack_trace trace;
1900 trace.nr_entries = log->trace_len;
1901 trace.entries = log->trace;
1903 pr_notice("Early log backtrace:\n");
1904 print_stack_trace(&trace, 2);
1908 * Kmemleak initialization.
1910 void __init kmemleak_init(void)
1913 unsigned long flags;
1915 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1916 if (!kmemleak_skip_disable) {
1917 kmemleak_early_log = 0;
1923 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1924 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1926 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1927 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1929 if (crt_early_log > ARRAY_SIZE(early_log))
1930 pr_warn("Early log buffer exceeded (%d), please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n",
1933 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1934 local_irq_save(flags);
1935 kmemleak_early_log = 0;
1936 if (kmemleak_error) {
1937 local_irq_restore(flags);
1940 kmemleak_enabled = 1;
1941 kmemleak_free_enabled = 1;
1943 local_irq_restore(flags);
1946 * This is the point where tracking allocations is safe. Automatic
1947 * scanning is started during the late initcall. Add the early logged
1948 * callbacks to the kmemleak infrastructure.
1950 for (i = 0; i < crt_early_log; i++) {
1951 struct early_log *log = &early_log[i];
1953 switch (log->op_type) {
1954 case KMEMLEAK_ALLOC:
1957 case KMEMLEAK_ALLOC_PERCPU:
1958 early_alloc_percpu(log);
1961 kmemleak_free(log->ptr);
1963 case KMEMLEAK_FREE_PART:
1964 kmemleak_free_part(log->ptr, log->size);
1966 case KMEMLEAK_FREE_PERCPU:
1967 kmemleak_free_percpu(log->ptr);
1969 case KMEMLEAK_NOT_LEAK:
1970 kmemleak_not_leak(log->ptr);
1972 case KMEMLEAK_IGNORE:
1973 kmemleak_ignore(log->ptr);
1975 case KMEMLEAK_SCAN_AREA:
1976 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
1978 case KMEMLEAK_NO_SCAN:
1979 kmemleak_no_scan(log->ptr);
1982 kmemleak_warn("Unknown early log operation: %d\n",
1986 if (kmemleak_warning) {
1987 print_log_trace(log);
1988 kmemleak_warning = 0;
1994 * Late initialization function.
1996 static int __init kmemleak_late_init(void)
1998 struct dentry *dentry;
2000 kmemleak_initialized = 1;
2002 if (kmemleak_error) {
2004 * Some error occurred and kmemleak was disabled. There is a
2005 * small chance that kmemleak_disable() was called immediately
2006 * after setting kmemleak_initialized and we may end up with
2007 * two clean-up threads but serialized by scan_mutex.
2009 schedule_work(&cleanup_work);
2013 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
2016 pr_warn("Failed to create the debugfs kmemleak file\n");
2017 mutex_lock(&scan_mutex);
2018 start_scan_thread();
2019 mutex_unlock(&scan_mutex);
2021 pr_info("Kernel memory leak detector initialized\n");
2025 late_initcall(kmemleak_late_init);