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/dev-tools/kmemleak.rst.
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/signal.h>
77 #include <linux/sched/task.h>
78 #include <linux/jiffies.h>
79 #include <linux/delay.h>
80 #include <linux/export.h>
81 #include <linux/kthread.h>
82 #include <linux/rbtree.h>
84 #include <linux/debugfs.h>
85 #include <linux/seq_file.h>
86 #include <linux/cpumask.h>
87 #include <linux/spinlock.h>
88 #include <linux/mutex.h>
89 #include <linux/rcupdate.h>
90 #include <linux/stacktrace.h>
91 #include <linux/cache.h>
92 #include <linux/percpu.h>
93 #include <linux/hardirq.h>
94 #include <linux/bootmem.h>
95 #include <linux/pfn.h>
96 #include <linux/mmzone.h>
97 #include <linux/slab.h>
98 #include <linux/thread_info.h>
99 #include <linux/err.h>
100 #include <linux/uaccess.h>
101 #include <linux/string.h>
102 #include <linux/nodemask.h>
103 #include <linux/mm.h>
104 #include <linux/workqueue.h>
105 #include <linux/crc32.h>
107 #include <asm/sections.h>
108 #include <asm/processor.h>
109 #include <linux/atomic.h>
111 #include <linux/kasan.h>
112 #include <linux/kmemcheck.h>
113 #include <linux/kmemleak.h>
114 #include <linux/memory_hotplug.h>
117 * Kmemleak configuration and common defines.
119 #define MAX_TRACE 16 /* stack trace length */
120 #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
121 #define SECS_FIRST_SCAN 60 /* delay before the first scan */
122 #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
123 #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
125 #define BYTES_PER_POINTER sizeof(void *)
127 /* GFP bitmask for kmemleak internal allocations */
128 #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
129 __GFP_NORETRY | __GFP_NOMEMALLOC | \
132 /* scanning area inside a memory block */
133 struct kmemleak_scan_area {
134 struct hlist_node node;
139 #define KMEMLEAK_GREY 0
140 #define KMEMLEAK_BLACK -1
143 * Structure holding the metadata for each allocated memory block.
144 * Modifications to such objects should be made while holding the
145 * object->lock. Insertions or deletions from object_list, gray_list or
146 * rb_node are already protected by the corresponding locks or mutex (see
147 * the notes on locking above). These objects are reference-counted
148 * (use_count) and freed using the RCU mechanism.
150 struct kmemleak_object {
152 unsigned long flags; /* object status flags */
153 struct list_head object_list;
154 struct list_head gray_list;
155 struct rb_node rb_node;
156 struct rcu_head rcu; /* object_list lockless traversal */
157 /* object usage count; object freed when use_count == 0 */
159 unsigned long pointer;
161 /* minimum number of a pointers found before it is considered leak */
163 /* the total number of pointers found pointing to this object */
165 /* checksum for detecting modified objects */
167 /* memory ranges to be scanned inside an object (empty for all) */
168 struct hlist_head area_list;
169 unsigned long trace[MAX_TRACE];
170 unsigned int trace_len;
171 unsigned long jiffies; /* creation timestamp */
172 pid_t pid; /* pid of the current task */
173 char comm[TASK_COMM_LEN]; /* executable name */
176 /* flag representing the memory block allocation status */
177 #define OBJECT_ALLOCATED (1 << 0)
178 /* flag set after the first reporting of an unreference object */
179 #define OBJECT_REPORTED (1 << 1)
180 /* flag set to not scan the object */
181 #define OBJECT_NO_SCAN (1 << 2)
183 /* number of bytes to print per line; must be 16 or 32 */
184 #define HEX_ROW_SIZE 16
185 /* number of bytes to print at a time (1, 2, 4, 8) */
186 #define HEX_GROUP_SIZE 1
187 /* include ASCII after the hex output */
189 /* max number of lines to be printed */
190 #define HEX_MAX_LINES 2
192 /* the list of all allocated objects */
193 static LIST_HEAD(object_list);
194 /* the list of gray-colored objects (see color_gray comment below) */
195 static LIST_HEAD(gray_list);
196 /* search tree for object boundaries */
197 static struct rb_root object_tree_root = RB_ROOT;
198 /* rw_lock protecting the access to object_list and object_tree_root */
199 static DEFINE_RWLOCK(kmemleak_lock);
201 /* allocation caches for kmemleak internal data */
202 static struct kmem_cache *object_cache;
203 static struct kmem_cache *scan_area_cache;
205 /* set if tracing memory operations is enabled */
206 static int kmemleak_enabled;
207 /* same as above but only for the kmemleak_free() callback */
208 static int kmemleak_free_enabled;
209 /* set in the late_initcall if there were no errors */
210 static int kmemleak_initialized;
211 /* enables or disables early logging of the memory operations */
212 static int kmemleak_early_log = 1;
213 /* set if a kmemleak warning was issued */
214 static int kmemleak_warning;
215 /* set if a fatal kmemleak error has occurred */
216 static int kmemleak_error;
218 /* minimum and maximum address that may be valid pointers */
219 static unsigned long min_addr = ULONG_MAX;
220 static unsigned long max_addr;
222 static struct task_struct *scan_thread;
223 /* used to avoid reporting of recently allocated objects */
224 static unsigned long jiffies_min_age;
225 static unsigned long jiffies_last_scan;
226 /* delay between automatic memory scannings */
227 static signed long jiffies_scan_wait;
228 /* enables or disables the task stacks scanning */
229 static int kmemleak_stack_scan = 1;
230 /* protects the memory scanning, parameters and debug/kmemleak file access */
231 static DEFINE_MUTEX(scan_mutex);
232 /* setting kmemleak=on, will set this var, skipping the disable */
233 static int kmemleak_skip_disable;
234 /* If there are leaks that can be reported */
235 static bool kmemleak_found_leaks;
238 * Early object allocation/freeing logging. Kmemleak is initialized after the
239 * kernel allocator. However, both the kernel allocator and kmemleak may
240 * allocate memory blocks which need to be tracked. Kmemleak defines an
241 * arbitrary buffer to hold the allocation/freeing information before it is
245 /* kmemleak operation type for early logging */
248 KMEMLEAK_ALLOC_PERCPU,
251 KMEMLEAK_FREE_PERCPU,
259 * Structure holding the information passed to kmemleak callbacks during the
263 int op_type; /* kmemleak operation type */
264 const void *ptr; /* allocated/freed memory block */
265 size_t size; /* memory block size */
266 int min_count; /* minimum reference count */
267 unsigned long trace[MAX_TRACE]; /* stack trace */
268 unsigned int trace_len; /* stack trace length */
271 /* early logging buffer and current position */
272 static struct early_log
273 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
274 static int crt_early_log __initdata;
276 static void kmemleak_disable(void);
279 * Print a warning and dump the stack trace.
281 #define kmemleak_warn(x...) do { \
284 kmemleak_warning = 1; \
288 * Macro invoked when a serious kmemleak condition occurred and cannot be
289 * recovered from. Kmemleak will be disabled and further allocation/freeing
290 * tracing no longer available.
292 #define kmemleak_stop(x...) do { \
294 kmemleak_disable(); \
298 * Printing of the objects hex dump to the seq file. The number of lines to be
299 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
300 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
301 * with the object->lock held.
303 static void hex_dump_object(struct seq_file *seq,
304 struct kmemleak_object *object)
306 const u8 *ptr = (const u8 *)object->pointer;
309 /* limit the number of lines to HEX_MAX_LINES */
310 len = min_t(size_t, object->size, HEX_MAX_LINES * HEX_ROW_SIZE);
312 seq_printf(seq, " hex dump (first %zu bytes):\n", len);
313 kasan_disable_current();
314 seq_hex_dump(seq, " ", DUMP_PREFIX_NONE, HEX_ROW_SIZE,
315 HEX_GROUP_SIZE, ptr, len, HEX_ASCII);
316 kasan_enable_current();
320 * Object colors, encoded with count and min_count:
321 * - white - orphan object, not enough references to it (count < min_count)
322 * - gray - not orphan, not marked as false positive (min_count == 0) or
323 * sufficient references to it (count >= min_count)
324 * - black - ignore, it doesn't contain references (e.g. text section)
325 * (min_count == -1). No function defined for this color.
326 * Newly created objects don't have any color assigned (object->count == -1)
327 * before the next memory scan when they become white.
329 static bool color_white(const struct kmemleak_object *object)
331 return object->count != KMEMLEAK_BLACK &&
332 object->count < object->min_count;
335 static bool color_gray(const struct kmemleak_object *object)
337 return object->min_count != KMEMLEAK_BLACK &&
338 object->count >= object->min_count;
342 * Objects are considered unreferenced only if their color is white, they have
343 * not be deleted and have a minimum age to avoid false positives caused by
344 * pointers temporarily stored in CPU registers.
346 static bool unreferenced_object(struct kmemleak_object *object)
348 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
349 time_before_eq(object->jiffies + jiffies_min_age,
354 * Printing of the unreferenced objects information to the seq file. The
355 * print_unreferenced function must be called with the object->lock held.
357 static void print_unreferenced(struct seq_file *seq,
358 struct kmemleak_object *object)
361 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
363 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
364 object->pointer, object->size);
365 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
366 object->comm, object->pid, object->jiffies,
367 msecs_age / 1000, msecs_age % 1000);
368 hex_dump_object(seq, object);
369 seq_printf(seq, " backtrace:\n");
371 for (i = 0; i < object->trace_len; i++) {
372 void *ptr = (void *)object->trace[i];
373 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
378 * Print the kmemleak_object information. This function is used mainly for
379 * debugging special cases when kmemleak operations. It must be called with
380 * the object->lock held.
382 static void dump_object_info(struct kmemleak_object *object)
384 struct stack_trace trace;
386 trace.nr_entries = object->trace_len;
387 trace.entries = object->trace;
389 pr_notice("Object 0x%08lx (size %zu):\n",
390 object->pointer, object->size);
391 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
392 object->comm, object->pid, object->jiffies);
393 pr_notice(" min_count = %d\n", object->min_count);
394 pr_notice(" count = %d\n", object->count);
395 pr_notice(" flags = 0x%lx\n", object->flags);
396 pr_notice(" checksum = %u\n", object->checksum);
397 pr_notice(" backtrace:\n");
398 print_stack_trace(&trace, 4);
402 * Look-up a memory block metadata (kmemleak_object) in the object search
403 * tree based on a pointer value. If alias is 0, only values pointing to the
404 * beginning of the memory block are allowed. The kmemleak_lock must be held
405 * when calling this function.
407 static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
409 struct rb_node *rb = object_tree_root.rb_node;
412 struct kmemleak_object *object =
413 rb_entry(rb, struct kmemleak_object, rb_node);
414 if (ptr < object->pointer)
415 rb = object->rb_node.rb_left;
416 else if (object->pointer + object->size <= ptr)
417 rb = object->rb_node.rb_right;
418 else if (object->pointer == ptr || alias)
421 kmemleak_warn("Found object by alias at 0x%08lx\n",
423 dump_object_info(object);
431 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
432 * that once an object's use_count reached 0, the RCU freeing was already
433 * registered and the object should no longer be used. This function must be
434 * called under the protection of rcu_read_lock().
436 static int get_object(struct kmemleak_object *object)
438 return atomic_inc_not_zero(&object->use_count);
442 * RCU callback to free a kmemleak_object.
444 static void free_object_rcu(struct rcu_head *rcu)
446 struct hlist_node *tmp;
447 struct kmemleak_scan_area *area;
448 struct kmemleak_object *object =
449 container_of(rcu, struct kmemleak_object, rcu);
452 * Once use_count is 0 (guaranteed by put_object), there is no other
453 * code accessing this object, hence no need for locking.
455 hlist_for_each_entry_safe(area, tmp, &object->area_list, node) {
456 hlist_del(&area->node);
457 kmem_cache_free(scan_area_cache, area);
459 kmem_cache_free(object_cache, object);
463 * Decrement the object use_count. Once the count is 0, free the object using
464 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
465 * delete_object() path, the delayed RCU freeing ensures that there is no
466 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
469 static void put_object(struct kmemleak_object *object)
471 if (!atomic_dec_and_test(&object->use_count))
474 /* should only get here after delete_object was called */
475 WARN_ON(object->flags & OBJECT_ALLOCATED);
477 call_rcu(&object->rcu, free_object_rcu);
481 * Look up an object in the object search tree and increase its use_count.
483 static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
486 struct kmemleak_object *object;
489 read_lock_irqsave(&kmemleak_lock, flags);
490 object = lookup_object(ptr, alias);
491 read_unlock_irqrestore(&kmemleak_lock, flags);
493 /* check whether the object is still available */
494 if (object && !get_object(object))
502 * Look up an object in the object search tree and remove it from both
503 * object_tree_root and object_list. The returned object's use_count should be
504 * at least 1, as initially set by create_object().
506 static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int alias)
509 struct kmemleak_object *object;
511 write_lock_irqsave(&kmemleak_lock, flags);
512 object = lookup_object(ptr, alias);
514 rb_erase(&object->rb_node, &object_tree_root);
515 list_del_rcu(&object->object_list);
517 write_unlock_irqrestore(&kmemleak_lock, flags);
523 * Save stack trace to the given array of MAX_TRACE size.
525 static int __save_stack_trace(unsigned long *trace)
527 struct stack_trace stack_trace;
529 stack_trace.max_entries = MAX_TRACE;
530 stack_trace.nr_entries = 0;
531 stack_trace.entries = trace;
532 stack_trace.skip = 2;
533 save_stack_trace(&stack_trace);
535 return stack_trace.nr_entries;
539 * Create the metadata (struct kmemleak_object) corresponding to an allocated
540 * memory block and add it to the object_list and object_tree_root.
542 static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
543 int min_count, gfp_t gfp)
546 struct kmemleak_object *object, *parent;
547 struct rb_node **link, *rb_parent;
549 object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
551 pr_warn("Cannot allocate a kmemleak_object structure\n");
556 INIT_LIST_HEAD(&object->object_list);
557 INIT_LIST_HEAD(&object->gray_list);
558 INIT_HLIST_HEAD(&object->area_list);
559 spin_lock_init(&object->lock);
560 atomic_set(&object->use_count, 1);
561 object->flags = OBJECT_ALLOCATED;
562 object->pointer = ptr;
564 object->min_count = min_count;
565 object->count = 0; /* white color initially */
566 object->jiffies = jiffies;
567 object->checksum = 0;
569 /* task information */
572 strncpy(object->comm, "hardirq", sizeof(object->comm));
573 } else if (in_softirq()) {
575 strncpy(object->comm, "softirq", sizeof(object->comm));
577 object->pid = current->pid;
579 * There is a small chance of a race with set_task_comm(),
580 * however using get_task_comm() here may cause locking
581 * dependency issues with current->alloc_lock. In the worst
582 * case, the command line is not correct.
584 strncpy(object->comm, current->comm, sizeof(object->comm));
587 /* kernel backtrace */
588 object->trace_len = __save_stack_trace(object->trace);
590 write_lock_irqsave(&kmemleak_lock, flags);
592 min_addr = min(min_addr, ptr);
593 max_addr = max(max_addr, ptr + size);
594 link = &object_tree_root.rb_node;
598 parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
599 if (ptr + size <= parent->pointer)
600 link = &parent->rb_node.rb_left;
601 else if (parent->pointer + parent->size <= ptr)
602 link = &parent->rb_node.rb_right;
604 kmemleak_stop("Cannot insert 0x%lx into the object search tree (overlaps existing)\n",
607 * No need for parent->lock here since "parent" cannot
608 * be freed while the kmemleak_lock is held.
610 dump_object_info(parent);
611 kmem_cache_free(object_cache, object);
616 rb_link_node(&object->rb_node, rb_parent, link);
617 rb_insert_color(&object->rb_node, &object_tree_root);
619 list_add_tail_rcu(&object->object_list, &object_list);
621 write_unlock_irqrestore(&kmemleak_lock, flags);
626 * Mark the object as not allocated and schedule RCU freeing via put_object().
628 static void __delete_object(struct kmemleak_object *object)
632 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
633 WARN_ON(atomic_read(&object->use_count) < 1);
636 * Locking here also ensures that the corresponding memory block
637 * cannot be freed when it is being scanned.
639 spin_lock_irqsave(&object->lock, flags);
640 object->flags &= ~OBJECT_ALLOCATED;
641 spin_unlock_irqrestore(&object->lock, flags);
646 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
649 static void delete_object_full(unsigned long ptr)
651 struct kmemleak_object *object;
653 object = find_and_remove_object(ptr, 0);
656 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
661 __delete_object(object);
665 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
666 * delete it. If the memory block is partially freed, the function may create
667 * additional metadata for the remaining parts of the block.
669 static void delete_object_part(unsigned long ptr, size_t size)
671 struct kmemleak_object *object;
672 unsigned long start, end;
674 object = find_and_remove_object(ptr, 1);
677 kmemleak_warn("Partially freeing unknown object at 0x%08lx (size %zu)\n",
684 * Create one or two objects that may result from the memory block
685 * split. Note that partial freeing is only done by free_bootmem() and
686 * this happens before kmemleak_init() is called. The path below is
687 * only executed during early log recording in kmemleak_init(), so
688 * GFP_KERNEL is enough.
690 start = object->pointer;
691 end = object->pointer + object->size;
693 create_object(start, ptr - start, object->min_count,
695 if (ptr + size < end)
696 create_object(ptr + size, end - ptr - size, object->min_count,
699 __delete_object(object);
702 static void __paint_it(struct kmemleak_object *object, int color)
704 object->min_count = color;
705 if (color == KMEMLEAK_BLACK)
706 object->flags |= OBJECT_NO_SCAN;
709 static void paint_it(struct kmemleak_object *object, int color)
713 spin_lock_irqsave(&object->lock, flags);
714 __paint_it(object, color);
715 spin_unlock_irqrestore(&object->lock, flags);
718 static void paint_ptr(unsigned long ptr, int color)
720 struct kmemleak_object *object;
722 object = find_and_get_object(ptr, 0);
724 kmemleak_warn("Trying to color unknown object at 0x%08lx as %s\n",
726 (color == KMEMLEAK_GREY) ? "Grey" :
727 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
730 paint_it(object, color);
735 * Mark an object permanently as gray-colored so that it can no longer be
736 * reported as a leak. This is used in general to mark a false positive.
738 static void make_gray_object(unsigned long ptr)
740 paint_ptr(ptr, KMEMLEAK_GREY);
744 * Mark the object as black-colored so that it is ignored from scans and
747 static void make_black_object(unsigned long ptr)
749 paint_ptr(ptr, KMEMLEAK_BLACK);
753 * Add a scanning area to the object. If at least one such area is added,
754 * kmemleak will only scan these ranges rather than the whole memory block.
756 static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
759 struct kmemleak_object *object;
760 struct kmemleak_scan_area *area;
762 object = find_and_get_object(ptr, 1);
764 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
769 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
771 pr_warn("Cannot allocate a scan area\n");
775 spin_lock_irqsave(&object->lock, flags);
776 if (size == SIZE_MAX) {
777 size = object->pointer + object->size - ptr;
778 } else if (ptr + size > object->pointer + object->size) {
779 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
780 dump_object_info(object);
781 kmem_cache_free(scan_area_cache, area);
785 INIT_HLIST_NODE(&area->node);
789 hlist_add_head(&area->node, &object->area_list);
791 spin_unlock_irqrestore(&object->lock, flags);
797 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
798 * pointer. Such object will not be scanned by kmemleak but references to it
801 static void object_no_scan(unsigned long ptr)
804 struct kmemleak_object *object;
806 object = find_and_get_object(ptr, 0);
808 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
812 spin_lock_irqsave(&object->lock, flags);
813 object->flags |= OBJECT_NO_SCAN;
814 spin_unlock_irqrestore(&object->lock, flags);
819 * Log an early kmemleak_* call to the early_log buffer. These calls will be
820 * processed later once kmemleak is fully initialized.
822 static void __init log_early(int op_type, const void *ptr, size_t size,
826 struct early_log *log;
828 if (kmemleak_error) {
829 /* kmemleak stopped recording, just count the requests */
834 if (crt_early_log >= ARRAY_SIZE(early_log)) {
841 * There is no need for locking since the kernel is still in UP mode
842 * at this stage. Disabling the IRQs is enough.
844 local_irq_save(flags);
845 log = &early_log[crt_early_log];
846 log->op_type = op_type;
849 log->min_count = min_count;
850 log->trace_len = __save_stack_trace(log->trace);
852 local_irq_restore(flags);
856 * Log an early allocated block and populate the stack trace.
858 static void early_alloc(struct early_log *log)
860 struct kmemleak_object *object;
864 if (!kmemleak_enabled || !log->ptr || IS_ERR(log->ptr))
868 * RCU locking needed to ensure object is not freed via put_object().
871 object = create_object((unsigned long)log->ptr, log->size,
872 log->min_count, GFP_ATOMIC);
875 spin_lock_irqsave(&object->lock, flags);
876 for (i = 0; i < log->trace_len; i++)
877 object->trace[i] = log->trace[i];
878 object->trace_len = log->trace_len;
879 spin_unlock_irqrestore(&object->lock, flags);
885 * Log an early allocated block and populate the stack trace.
887 static void early_alloc_percpu(struct early_log *log)
890 const void __percpu *ptr = log->ptr;
892 for_each_possible_cpu(cpu) {
893 log->ptr = per_cpu_ptr(ptr, cpu);
899 * kmemleak_alloc - register a newly allocated object
900 * @ptr: pointer to beginning of the object
901 * @size: size of the object
902 * @min_count: minimum number of references to this object. If during memory
903 * scanning a number of references less than @min_count is found,
904 * the object is reported as a memory leak. If @min_count is 0,
905 * the object is never reported as a leak. If @min_count is -1,
906 * the object is ignored (not scanned and not reported as a leak)
907 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
909 * This function is called from the kernel allocators when a new object
910 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
912 void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
915 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
917 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
918 create_object((unsigned long)ptr, size, min_count, gfp);
919 else if (kmemleak_early_log)
920 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
922 EXPORT_SYMBOL_GPL(kmemleak_alloc);
925 * kmemleak_alloc_percpu - register a newly allocated __percpu object
926 * @ptr: __percpu pointer to beginning of the object
927 * @size: size of the object
928 * @gfp: flags used for kmemleak internal memory allocations
930 * This function is called from the kernel percpu allocator when a new object
931 * (memory block) is allocated (alloc_percpu).
933 void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size,
938 pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
941 * Percpu allocations are only scanned and not reported as leaks
942 * (min_count is set to 0).
944 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
945 for_each_possible_cpu(cpu)
946 create_object((unsigned long)per_cpu_ptr(ptr, cpu),
948 else if (kmemleak_early_log)
949 log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
951 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
954 * kmemleak_free - unregister a previously registered object
955 * @ptr: pointer to beginning of the object
957 * This function is called from the kernel allocators when an object (memory
958 * block) is freed (kmem_cache_free, kfree, vfree etc.).
960 void __ref kmemleak_free(const void *ptr)
962 pr_debug("%s(0x%p)\n", __func__, ptr);
964 if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
965 delete_object_full((unsigned long)ptr);
966 else if (kmemleak_early_log)
967 log_early(KMEMLEAK_FREE, ptr, 0, 0);
969 EXPORT_SYMBOL_GPL(kmemleak_free);
972 * kmemleak_free_part - partially unregister a previously registered object
973 * @ptr: pointer to the beginning or inside the object. This also
974 * represents the start of the range to be freed
975 * @size: size to be unregistered
977 * This function is called when only a part of a memory block is freed
978 * (usually from the bootmem allocator).
980 void __ref kmemleak_free_part(const void *ptr, size_t size)
982 pr_debug("%s(0x%p)\n", __func__, ptr);
984 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
985 delete_object_part((unsigned long)ptr, size);
986 else if (kmemleak_early_log)
987 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
989 EXPORT_SYMBOL_GPL(kmemleak_free_part);
992 * kmemleak_free_percpu - unregister a previously registered __percpu object
993 * @ptr: __percpu pointer to beginning of the object
995 * This function is called from the kernel percpu allocator when an object
996 * (memory block) is freed (free_percpu).
998 void __ref kmemleak_free_percpu(const void __percpu *ptr)
1002 pr_debug("%s(0x%p)\n", __func__, ptr);
1004 if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
1005 for_each_possible_cpu(cpu)
1006 delete_object_full((unsigned long)per_cpu_ptr(ptr,
1008 else if (kmemleak_early_log)
1009 log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
1011 EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
1014 * kmemleak_update_trace - update object allocation stack trace
1015 * @ptr: pointer to beginning of the object
1017 * Override the object allocation stack trace for cases where the actual
1018 * allocation place is not always useful.
1020 void __ref kmemleak_update_trace(const void *ptr)
1022 struct kmemleak_object *object;
1023 unsigned long flags;
1025 pr_debug("%s(0x%p)\n", __func__, ptr);
1027 if (!kmemleak_enabled || IS_ERR_OR_NULL(ptr))
1030 object = find_and_get_object((unsigned long)ptr, 1);
1033 kmemleak_warn("Updating stack trace for unknown object at %p\n",
1039 spin_lock_irqsave(&object->lock, flags);
1040 object->trace_len = __save_stack_trace(object->trace);
1041 spin_unlock_irqrestore(&object->lock, flags);
1045 EXPORT_SYMBOL(kmemleak_update_trace);
1048 * kmemleak_not_leak - mark an allocated object as false positive
1049 * @ptr: pointer to beginning of the object
1051 * Calling this function on an object will cause the memory block to no longer
1052 * be reported as leak and always be scanned.
1054 void __ref kmemleak_not_leak(const void *ptr)
1056 pr_debug("%s(0x%p)\n", __func__, ptr);
1058 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1059 make_gray_object((unsigned long)ptr);
1060 else if (kmemleak_early_log)
1061 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
1063 EXPORT_SYMBOL(kmemleak_not_leak);
1066 * kmemleak_ignore - ignore an allocated object
1067 * @ptr: pointer to beginning of the object
1069 * Calling this function on an object will cause the memory block to be
1070 * ignored (not scanned and not reported as a leak). This is usually done when
1071 * it is known that the corresponding block is not a leak and does not contain
1072 * any references to other allocated memory blocks.
1074 void __ref kmemleak_ignore(const void *ptr)
1076 pr_debug("%s(0x%p)\n", __func__, ptr);
1078 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1079 make_black_object((unsigned long)ptr);
1080 else if (kmemleak_early_log)
1081 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
1083 EXPORT_SYMBOL(kmemleak_ignore);
1086 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1087 * @ptr: pointer to beginning or inside the object. This also
1088 * represents the start of the scan area
1089 * @size: size of the scan area
1090 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1092 * This function is used when it is known that only certain parts of an object
1093 * contain references to other objects. Kmemleak will only scan these areas
1094 * reducing the number false negatives.
1096 void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
1098 pr_debug("%s(0x%p)\n", __func__, ptr);
1100 if (kmemleak_enabled && ptr && size && !IS_ERR(ptr))
1101 add_scan_area((unsigned long)ptr, size, gfp);
1102 else if (kmemleak_early_log)
1103 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
1105 EXPORT_SYMBOL(kmemleak_scan_area);
1108 * kmemleak_no_scan - do not scan an allocated object
1109 * @ptr: pointer to beginning of the object
1111 * This function notifies kmemleak not to scan the given memory block. Useful
1112 * in situations where it is known that the given object does not contain any
1113 * references to other objects. Kmemleak will not scan such objects reducing
1114 * the number of false negatives.
1116 void __ref kmemleak_no_scan(const void *ptr)
1118 pr_debug("%s(0x%p)\n", __func__, ptr);
1120 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1121 object_no_scan((unsigned long)ptr);
1122 else if (kmemleak_early_log)
1123 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
1125 EXPORT_SYMBOL(kmemleak_no_scan);
1128 * kmemleak_alloc_phys - similar to kmemleak_alloc but taking a physical
1131 void __ref kmemleak_alloc_phys(phys_addr_t phys, size_t size, int min_count,
1134 if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1135 kmemleak_alloc(__va(phys), size, min_count, gfp);
1137 EXPORT_SYMBOL(kmemleak_alloc_phys);
1140 * kmemleak_free_part_phys - similar to kmemleak_free_part but taking a
1141 * physical address argument
1143 void __ref kmemleak_free_part_phys(phys_addr_t phys, size_t size)
1145 if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1146 kmemleak_free_part(__va(phys), size);
1148 EXPORT_SYMBOL(kmemleak_free_part_phys);
1151 * kmemleak_not_leak_phys - similar to kmemleak_not_leak but taking a physical
1154 void __ref kmemleak_not_leak_phys(phys_addr_t phys)
1156 if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1157 kmemleak_not_leak(__va(phys));
1159 EXPORT_SYMBOL(kmemleak_not_leak_phys);
1162 * kmemleak_ignore_phys - similar to kmemleak_ignore but taking a physical
1165 void __ref kmemleak_ignore_phys(phys_addr_t phys)
1167 if (!IS_ENABLED(CONFIG_HIGHMEM) || PHYS_PFN(phys) < max_low_pfn)
1168 kmemleak_ignore(__va(phys));
1170 EXPORT_SYMBOL(kmemleak_ignore_phys);
1173 * Update an object's checksum and return true if it was modified.
1175 static bool update_checksum(struct kmemleak_object *object)
1177 u32 old_csum = object->checksum;
1179 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
1182 kasan_disable_current();
1183 object->checksum = crc32(0, (void *)object->pointer, object->size);
1184 kasan_enable_current();
1186 return object->checksum != old_csum;
1190 * Memory scanning is a long process and it needs to be interruptable. This
1191 * function checks whether such interrupt condition occurred.
1193 static int scan_should_stop(void)
1195 if (!kmemleak_enabled)
1199 * This function may be called from either process or kthread context,
1200 * hence the need to check for both stop conditions.
1203 return signal_pending(current);
1205 return kthread_should_stop();
1211 * Scan a memory block (exclusive range) for valid pointers and add those
1212 * found to the gray list.
1214 static void scan_block(void *_start, void *_end,
1215 struct kmemleak_object *scanned)
1218 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1219 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1220 unsigned long flags;
1222 read_lock_irqsave(&kmemleak_lock, flags);
1223 for (ptr = start; ptr < end; ptr++) {
1224 struct kmemleak_object *object;
1225 unsigned long pointer;
1227 if (scan_should_stop())
1230 /* don't scan uninitialized memory */
1231 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1235 kasan_disable_current();
1237 kasan_enable_current();
1239 if (pointer < min_addr || pointer >= max_addr)
1243 * No need for get_object() here since we hold kmemleak_lock.
1244 * object->use_count cannot be dropped to 0 while the object
1245 * is still present in object_tree_root and object_list
1246 * (with updates protected by kmemleak_lock).
1248 object = lookup_object(pointer, 1);
1251 if (object == scanned)
1252 /* self referenced, ignore */
1256 * Avoid the lockdep recursive warning on object->lock being
1257 * previously acquired in scan_object(). These locks are
1258 * enclosed by scan_mutex.
1260 spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
1261 if (!color_white(object)) {
1262 /* non-orphan, ignored or new */
1263 spin_unlock(&object->lock);
1268 * Increase the object's reference count (number of pointers
1269 * to the memory block). If this count reaches the required
1270 * minimum, the object's color will become gray and it will be
1271 * added to the gray_list.
1274 if (color_gray(object)) {
1275 /* put_object() called when removing from gray_list */
1276 WARN_ON(!get_object(object));
1277 list_add_tail(&object->gray_list, &gray_list);
1279 spin_unlock(&object->lock);
1281 read_unlock_irqrestore(&kmemleak_lock, flags);
1285 * Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency.
1287 static void scan_large_block(void *start, void *end)
1291 while (start < end) {
1292 next = min(start + MAX_SCAN_SIZE, end);
1293 scan_block(start, next, NULL);
1300 * Scan a memory block corresponding to a kmemleak_object. A condition is
1301 * that object->use_count >= 1.
1303 static void scan_object(struct kmemleak_object *object)
1305 struct kmemleak_scan_area *area;
1306 unsigned long flags;
1309 * Once the object->lock is acquired, the corresponding memory block
1310 * cannot be freed (the same lock is acquired in delete_object).
1312 spin_lock_irqsave(&object->lock, flags);
1313 if (object->flags & OBJECT_NO_SCAN)
1315 if (!(object->flags & OBJECT_ALLOCATED))
1316 /* already freed object */
1318 if (hlist_empty(&object->area_list)) {
1319 void *start = (void *)object->pointer;
1320 void *end = (void *)(object->pointer + object->size);
1324 next = min(start + MAX_SCAN_SIZE, end);
1325 scan_block(start, next, object);
1331 spin_unlock_irqrestore(&object->lock, flags);
1333 spin_lock_irqsave(&object->lock, flags);
1334 } while (object->flags & OBJECT_ALLOCATED);
1336 hlist_for_each_entry(area, &object->area_list, node)
1337 scan_block((void *)area->start,
1338 (void *)(area->start + area->size),
1341 spin_unlock_irqrestore(&object->lock, flags);
1345 * Scan the objects already referenced (gray objects). More objects will be
1346 * referenced and, if there are no memory leaks, all the objects are scanned.
1348 static void scan_gray_list(void)
1350 struct kmemleak_object *object, *tmp;
1353 * The list traversal is safe for both tail additions and removals
1354 * from inside the loop. The kmemleak objects cannot be freed from
1355 * outside the loop because their use_count was incremented.
1357 object = list_entry(gray_list.next, typeof(*object), gray_list);
1358 while (&object->gray_list != &gray_list) {
1361 /* may add new objects to the list */
1362 if (!scan_should_stop())
1363 scan_object(object);
1365 tmp = list_entry(object->gray_list.next, typeof(*object),
1368 /* remove the object from the list and release it */
1369 list_del(&object->gray_list);
1374 WARN_ON(!list_empty(&gray_list));
1378 * Scan data sections and all the referenced memory blocks allocated via the
1379 * kernel's standard allocators. This function must be called with the
1382 static void kmemleak_scan(void)
1384 unsigned long flags;
1385 struct kmemleak_object *object;
1389 jiffies_last_scan = jiffies;
1391 /* prepare the kmemleak_object's */
1393 list_for_each_entry_rcu(object, &object_list, object_list) {
1394 spin_lock_irqsave(&object->lock, flags);
1397 * With a few exceptions there should be a maximum of
1398 * 1 reference to any object at this point.
1400 if (atomic_read(&object->use_count) > 1) {
1401 pr_debug("object->use_count = %d\n",
1402 atomic_read(&object->use_count));
1403 dump_object_info(object);
1406 /* reset the reference count (whiten the object) */
1408 if (color_gray(object) && get_object(object))
1409 list_add_tail(&object->gray_list, &gray_list);
1411 spin_unlock_irqrestore(&object->lock, flags);
1415 /* data/bss scanning */
1416 scan_large_block(_sdata, _edata);
1417 scan_large_block(__bss_start, __bss_stop);
1418 scan_large_block(__start_data_ro_after_init, __end_data_ro_after_init);
1421 /* per-cpu sections scanning */
1422 for_each_possible_cpu(i)
1423 scan_large_block(__per_cpu_start + per_cpu_offset(i),
1424 __per_cpu_end + per_cpu_offset(i));
1428 * Struct page scanning for each node.
1431 for_each_online_node(i) {
1432 unsigned long start_pfn = node_start_pfn(i);
1433 unsigned long end_pfn = node_end_pfn(i);
1436 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1439 if (!pfn_valid(pfn))
1441 page = pfn_to_page(pfn);
1442 /* only scan if page is in use */
1443 if (page_count(page) == 0)
1445 scan_block(page, page + 1, NULL);
1451 * Scanning the task stacks (may introduce false negatives).
1453 if (kmemleak_stack_scan) {
1454 struct task_struct *p, *g;
1456 read_lock(&tasklist_lock);
1457 do_each_thread(g, p) {
1458 void *stack = try_get_task_stack(p);
1460 scan_block(stack, stack + THREAD_SIZE, NULL);
1463 } while_each_thread(g, p);
1464 read_unlock(&tasklist_lock);
1468 * Scan the objects already referenced from the sections scanned
1474 * Check for new or unreferenced objects modified since the previous
1475 * scan and color them gray until the next scan.
1478 list_for_each_entry_rcu(object, &object_list, object_list) {
1479 spin_lock_irqsave(&object->lock, flags);
1480 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1481 && update_checksum(object) && get_object(object)) {
1482 /* color it gray temporarily */
1483 object->count = object->min_count;
1484 list_add_tail(&object->gray_list, &gray_list);
1486 spin_unlock_irqrestore(&object->lock, flags);
1491 * Re-scan the gray list for modified unreferenced objects.
1496 * If scanning was stopped do not report any new unreferenced objects.
1498 if (scan_should_stop())
1502 * Scanning result reporting.
1505 list_for_each_entry_rcu(object, &object_list, object_list) {
1506 spin_lock_irqsave(&object->lock, flags);
1507 if (unreferenced_object(object) &&
1508 !(object->flags & OBJECT_REPORTED)) {
1509 object->flags |= OBJECT_REPORTED;
1512 spin_unlock_irqrestore(&object->lock, flags);
1517 kmemleak_found_leaks = true;
1519 pr_info("%d new suspected memory leaks (see /sys/kernel/debug/kmemleak)\n",
1526 * Thread function performing automatic memory scanning. Unreferenced objects
1527 * at the end of a memory scan are reported but only the first time.
1529 static int kmemleak_scan_thread(void *arg)
1531 static int first_run = 1;
1533 pr_info("Automatic memory scanning thread started\n");
1534 set_user_nice(current, 10);
1537 * Wait before the first scan to allow the system to fully initialize.
1540 signed long timeout = msecs_to_jiffies(SECS_FIRST_SCAN * 1000);
1542 while (timeout && !kthread_should_stop())
1543 timeout = schedule_timeout_interruptible(timeout);
1546 while (!kthread_should_stop()) {
1547 signed long timeout = jiffies_scan_wait;
1549 mutex_lock(&scan_mutex);
1551 mutex_unlock(&scan_mutex);
1553 /* wait before the next scan */
1554 while (timeout && !kthread_should_stop())
1555 timeout = schedule_timeout_interruptible(timeout);
1558 pr_info("Automatic memory scanning thread ended\n");
1564 * Start the automatic memory scanning thread. This function must be called
1565 * with the scan_mutex held.
1567 static void start_scan_thread(void)
1571 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1572 if (IS_ERR(scan_thread)) {
1573 pr_warn("Failed to create the scan thread\n");
1579 * Stop the automatic memory scanning thread. This function must be called
1580 * with the scan_mutex held.
1582 static void stop_scan_thread(void)
1585 kthread_stop(scan_thread);
1591 * Iterate over the object_list and return the first valid object at or after
1592 * the required position with its use_count incremented. The function triggers
1593 * a memory scanning when the pos argument points to the first position.
1595 static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1597 struct kmemleak_object *object;
1601 err = mutex_lock_interruptible(&scan_mutex);
1603 return ERR_PTR(err);
1606 list_for_each_entry_rcu(object, &object_list, object_list) {
1609 if (get_object(object))
1618 * Return the next object in the object_list. The function decrements the
1619 * use_count of the previous object and increases that of the next one.
1621 static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1623 struct kmemleak_object *prev_obj = v;
1624 struct kmemleak_object *next_obj = NULL;
1625 struct kmemleak_object *obj = prev_obj;
1629 list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
1630 if (get_object(obj)) {
1636 put_object(prev_obj);
1641 * Decrement the use_count of the last object required, if any.
1643 static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1647 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1648 * waiting was interrupted, so only release it if !IS_ERR.
1651 mutex_unlock(&scan_mutex);
1658 * Print the information for an unreferenced object to the seq file.
1660 static int kmemleak_seq_show(struct seq_file *seq, void *v)
1662 struct kmemleak_object *object = v;
1663 unsigned long flags;
1665 spin_lock_irqsave(&object->lock, flags);
1666 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
1667 print_unreferenced(seq, object);
1668 spin_unlock_irqrestore(&object->lock, flags);
1672 static const struct seq_operations kmemleak_seq_ops = {
1673 .start = kmemleak_seq_start,
1674 .next = kmemleak_seq_next,
1675 .stop = kmemleak_seq_stop,
1676 .show = kmemleak_seq_show,
1679 static int kmemleak_open(struct inode *inode, struct file *file)
1681 return seq_open(file, &kmemleak_seq_ops);
1684 static int dump_str_object_info(const char *str)
1686 unsigned long flags;
1687 struct kmemleak_object *object;
1690 if (kstrtoul(str, 0, &addr))
1692 object = find_and_get_object(addr, 0);
1694 pr_info("Unknown object at 0x%08lx\n", addr);
1698 spin_lock_irqsave(&object->lock, flags);
1699 dump_object_info(object);
1700 spin_unlock_irqrestore(&object->lock, flags);
1707 * We use grey instead of black to ensure we can do future scans on the same
1708 * objects. If we did not do future scans these black objects could
1709 * potentially contain references to newly allocated objects in the future and
1710 * we'd end up with false positives.
1712 static void kmemleak_clear(void)
1714 struct kmemleak_object *object;
1715 unsigned long flags;
1718 list_for_each_entry_rcu(object, &object_list, object_list) {
1719 spin_lock_irqsave(&object->lock, flags);
1720 if ((object->flags & OBJECT_REPORTED) &&
1721 unreferenced_object(object))
1722 __paint_it(object, KMEMLEAK_GREY);
1723 spin_unlock_irqrestore(&object->lock, flags);
1727 kmemleak_found_leaks = false;
1730 static void __kmemleak_do_cleanup(void);
1733 * File write operation to configure kmemleak at run-time. The following
1734 * commands can be written to the /sys/kernel/debug/kmemleak file:
1735 * off - disable kmemleak (irreversible)
1736 * stack=on - enable the task stacks scanning
1737 * stack=off - disable the tasks stacks scanning
1738 * scan=on - start the automatic memory scanning thread
1739 * scan=off - stop the automatic memory scanning thread
1740 * scan=... - set the automatic memory scanning period in seconds (0 to
1742 * scan - trigger a memory scan
1743 * clear - mark all current reported unreferenced kmemleak objects as
1744 * grey to ignore printing them, or free all kmemleak objects
1745 * if kmemleak has been disabled.
1746 * dump=... - dump information about the object found at the given address
1748 static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1749 size_t size, loff_t *ppos)
1755 buf_size = min(size, (sizeof(buf) - 1));
1756 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1760 ret = mutex_lock_interruptible(&scan_mutex);
1764 if (strncmp(buf, "clear", 5) == 0) {
1765 if (kmemleak_enabled)
1768 __kmemleak_do_cleanup();
1772 if (!kmemleak_enabled) {
1777 if (strncmp(buf, "off", 3) == 0)
1779 else if (strncmp(buf, "stack=on", 8) == 0)
1780 kmemleak_stack_scan = 1;
1781 else if (strncmp(buf, "stack=off", 9) == 0)
1782 kmemleak_stack_scan = 0;
1783 else if (strncmp(buf, "scan=on", 7) == 0)
1784 start_scan_thread();
1785 else if (strncmp(buf, "scan=off", 8) == 0)
1787 else if (strncmp(buf, "scan=", 5) == 0) {
1790 ret = kstrtoul(buf + 5, 0, &secs);
1795 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1796 start_scan_thread();
1798 } else if (strncmp(buf, "scan", 4) == 0)
1800 else if (strncmp(buf, "dump=", 5) == 0)
1801 ret = dump_str_object_info(buf + 5);
1806 mutex_unlock(&scan_mutex);
1810 /* ignore the rest of the buffer, only one command at a time */
1815 static const struct file_operations kmemleak_fops = {
1816 .owner = THIS_MODULE,
1817 .open = kmemleak_open,
1819 .write = kmemleak_write,
1820 .llseek = seq_lseek,
1821 .release = seq_release,
1824 static void __kmemleak_do_cleanup(void)
1826 struct kmemleak_object *object;
1829 list_for_each_entry_rcu(object, &object_list, object_list)
1830 delete_object_full(object->pointer);
1835 * Stop the memory scanning thread and free the kmemleak internal objects if
1836 * no previous scan thread (otherwise, kmemleak may still have some useful
1837 * information on memory leaks).
1839 static void kmemleak_do_cleanup(struct work_struct *work)
1844 * Once the scan thread has stopped, it is safe to no longer track
1845 * object freeing. Ordering of the scan thread stopping and the memory
1846 * accesses below is guaranteed by the kthread_stop() function.
1848 kmemleak_free_enabled = 0;
1850 if (!kmemleak_found_leaks)
1851 __kmemleak_do_cleanup();
1853 pr_info("Kmemleak disabled without freeing internal data. Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\".\n");
1856 static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
1859 * Disable kmemleak. No memory allocation/freeing will be traced once this
1860 * function is called. Disabling kmemleak is an irreversible operation.
1862 static void kmemleak_disable(void)
1864 /* atomically check whether it was already invoked */
1865 if (cmpxchg(&kmemleak_error, 0, 1))
1868 /* stop any memory operation tracing */
1869 kmemleak_enabled = 0;
1871 /* check whether it is too early for a kernel thread */
1872 if (kmemleak_initialized)
1873 schedule_work(&cleanup_work);
1875 kmemleak_free_enabled = 0;
1877 pr_info("Kernel memory leak detector disabled\n");
1881 * Allow boot-time kmemleak disabling (enabled by default).
1883 static int kmemleak_boot_config(char *str)
1887 if (strcmp(str, "off") == 0)
1889 else if (strcmp(str, "on") == 0)
1890 kmemleak_skip_disable = 1;
1895 early_param("kmemleak", kmemleak_boot_config);
1897 static void __init print_log_trace(struct early_log *log)
1899 struct stack_trace trace;
1901 trace.nr_entries = log->trace_len;
1902 trace.entries = log->trace;
1904 pr_notice("Early log backtrace:\n");
1905 print_stack_trace(&trace, 2);
1909 * Kmemleak initialization.
1911 void __init kmemleak_init(void)
1914 unsigned long flags;
1916 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1917 if (!kmemleak_skip_disable) {
1918 kmemleak_early_log = 0;
1924 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1925 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1927 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1928 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1930 if (crt_early_log > ARRAY_SIZE(early_log))
1931 pr_warn("Early log buffer exceeded (%d), please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n",
1934 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1935 local_irq_save(flags);
1936 kmemleak_early_log = 0;
1937 if (kmemleak_error) {
1938 local_irq_restore(flags);
1941 kmemleak_enabled = 1;
1942 kmemleak_free_enabled = 1;
1944 local_irq_restore(flags);
1947 * This is the point where tracking allocations is safe. Automatic
1948 * scanning is started during the late initcall. Add the early logged
1949 * callbacks to the kmemleak infrastructure.
1951 for (i = 0; i < crt_early_log; i++) {
1952 struct early_log *log = &early_log[i];
1954 switch (log->op_type) {
1955 case KMEMLEAK_ALLOC:
1958 case KMEMLEAK_ALLOC_PERCPU:
1959 early_alloc_percpu(log);
1962 kmemleak_free(log->ptr);
1964 case KMEMLEAK_FREE_PART:
1965 kmemleak_free_part(log->ptr, log->size);
1967 case KMEMLEAK_FREE_PERCPU:
1968 kmemleak_free_percpu(log->ptr);
1970 case KMEMLEAK_NOT_LEAK:
1971 kmemleak_not_leak(log->ptr);
1973 case KMEMLEAK_IGNORE:
1974 kmemleak_ignore(log->ptr);
1976 case KMEMLEAK_SCAN_AREA:
1977 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
1979 case KMEMLEAK_NO_SCAN:
1980 kmemleak_no_scan(log->ptr);
1983 kmemleak_warn("Unknown early log operation: %d\n",
1987 if (kmemleak_warning) {
1988 print_log_trace(log);
1989 kmemleak_warning = 0;
1995 * Late initialization function.
1997 static int __init kmemleak_late_init(void)
1999 struct dentry *dentry;
2001 kmemleak_initialized = 1;
2003 if (kmemleak_error) {
2005 * Some error occurred and kmemleak was disabled. There is a
2006 * small chance that kmemleak_disable() was called immediately
2007 * after setting kmemleak_initialized and we may end up with
2008 * two clean-up threads but serialized by scan_mutex.
2010 schedule_work(&cleanup_work);
2014 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
2017 pr_warn("Failed to create the debugfs kmemleak file\n");
2018 mutex_lock(&scan_mutex);
2019 start_scan_thread();
2020 mutex_unlock(&scan_mutex);
2022 pr_info("Kernel memory leak detector initialized\n");
2026 late_initcall(kmemleak_late_init);