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/mmzone.h>
94 #include <linux/slab.h>
95 #include <linux/thread_info.h>
96 #include <linux/err.h>
97 #include <linux/uaccess.h>
98 #include <linux/string.h>
99 #include <linux/nodemask.h>
100 #include <linux/mm.h>
101 #include <linux/workqueue.h>
102 #include <linux/crc32.h>
104 #include <asm/sections.h>
105 #include <asm/processor.h>
106 #include <linux/atomic.h>
108 #include <linux/kasan.h>
109 #include <linux/kmemcheck.h>
110 #include <linux/kmemleak.h>
111 #include <linux/memory_hotplug.h>
114 * Kmemleak configuration and common defines.
116 #define MAX_TRACE 16 /* stack trace length */
117 #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
118 #define SECS_FIRST_SCAN 60 /* delay before the first scan */
119 #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
120 #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
122 #define BYTES_PER_POINTER sizeof(void *)
124 /* GFP bitmask for kmemleak internal allocations */
125 #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC | \
126 __GFP_NOACCOUNT)) | \
127 __GFP_NORETRY | __GFP_NOMEMALLOC | \
130 /* scanning area inside a memory block */
131 struct kmemleak_scan_area {
132 struct hlist_node node;
137 #define KMEMLEAK_GREY 0
138 #define KMEMLEAK_BLACK -1
141 * Structure holding the metadata for each allocated memory block.
142 * Modifications to such objects should be made while holding the
143 * object->lock. Insertions or deletions from object_list, gray_list or
144 * rb_node are already protected by the corresponding locks or mutex (see
145 * the notes on locking above). These objects are reference-counted
146 * (use_count) and freed using the RCU mechanism.
148 struct kmemleak_object {
150 unsigned long flags; /* object status flags */
151 struct list_head object_list;
152 struct list_head gray_list;
153 struct rb_node rb_node;
154 struct rcu_head rcu; /* object_list lockless traversal */
155 /* object usage count; object freed when use_count == 0 */
157 unsigned long pointer;
159 /* minimum number of a pointers found before it is considered leak */
161 /* the total number of pointers found pointing to this object */
163 /* checksum for detecting modified objects */
165 /* memory ranges to be scanned inside an object (empty for all) */
166 struct hlist_head area_list;
167 unsigned long trace[MAX_TRACE];
168 unsigned int trace_len;
169 unsigned long jiffies; /* creation timestamp */
170 pid_t pid; /* pid of the current task */
171 char comm[TASK_COMM_LEN]; /* executable name */
174 /* flag representing the memory block allocation status */
175 #define OBJECT_ALLOCATED (1 << 0)
176 /* flag set after the first reporting of an unreference object */
177 #define OBJECT_REPORTED (1 << 1)
178 /* flag set to not scan the object */
179 #define OBJECT_NO_SCAN (1 << 2)
181 /* number of bytes to print per line; must be 16 or 32 */
182 #define HEX_ROW_SIZE 16
183 /* number of bytes to print at a time (1, 2, 4, 8) */
184 #define HEX_GROUP_SIZE 1
185 /* include ASCII after the hex output */
187 /* max number of lines to be printed */
188 #define HEX_MAX_LINES 2
190 /* the list of all allocated objects */
191 static LIST_HEAD(object_list);
192 /* the list of gray-colored objects (see color_gray comment below) */
193 static LIST_HEAD(gray_list);
194 /* search tree for object boundaries */
195 static struct rb_root object_tree_root = RB_ROOT;
196 /* rw_lock protecting the access to object_list and object_tree_root */
197 static DEFINE_RWLOCK(kmemleak_lock);
199 /* allocation caches for kmemleak internal data */
200 static struct kmem_cache *object_cache;
201 static struct kmem_cache *scan_area_cache;
203 /* set if tracing memory operations is enabled */
204 static int kmemleak_enabled;
205 /* same as above but only for the kmemleak_free() callback */
206 static int kmemleak_free_enabled;
207 /* set in the late_initcall if there were no errors */
208 static int kmemleak_initialized;
209 /* enables or disables early logging of the memory operations */
210 static int kmemleak_early_log = 1;
211 /* set if a kmemleak warning was issued */
212 static int kmemleak_warning;
213 /* set if a fatal kmemleak error has occurred */
214 static int kmemleak_error;
216 /* minimum and maximum address that may be valid pointers */
217 static unsigned long min_addr = ULONG_MAX;
218 static unsigned long max_addr;
220 static struct task_struct *scan_thread;
221 /* used to avoid reporting of recently allocated objects */
222 static unsigned long jiffies_min_age;
223 static unsigned long jiffies_last_scan;
224 /* delay between automatic memory scannings */
225 static signed long jiffies_scan_wait;
226 /* enables or disables the task stacks scanning */
227 static int kmemleak_stack_scan = 1;
228 /* protects the memory scanning, parameters and debug/kmemleak file access */
229 static DEFINE_MUTEX(scan_mutex);
230 /* setting kmemleak=on, will set this var, skipping the disable */
231 static int kmemleak_skip_disable;
232 /* If there are leaks that can be reported */
233 static bool kmemleak_found_leaks;
236 * Early object allocation/freeing logging. Kmemleak is initialized after the
237 * kernel allocator. However, both the kernel allocator and kmemleak may
238 * allocate memory blocks which need to be tracked. Kmemleak defines an
239 * arbitrary buffer to hold the allocation/freeing information before it is
243 /* kmemleak operation type for early logging */
246 KMEMLEAK_ALLOC_PERCPU,
249 KMEMLEAK_FREE_PERCPU,
257 * Structure holding the information passed to kmemleak callbacks during the
261 int op_type; /* kmemleak operation type */
262 const void *ptr; /* allocated/freed memory block */
263 size_t size; /* memory block size */
264 int min_count; /* minimum reference count */
265 unsigned long trace[MAX_TRACE]; /* stack trace */
266 unsigned int trace_len; /* stack trace length */
269 /* early logging buffer and current position */
270 static struct early_log
271 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
272 static int crt_early_log __initdata;
274 static void kmemleak_disable(void);
277 * Print a warning and dump the stack trace.
279 #define kmemleak_warn(x...) do { \
282 kmemleak_warning = 1; \
286 * Macro invoked when a serious kmemleak condition occurred and cannot be
287 * recovered from. Kmemleak will be disabled and further allocation/freeing
288 * tracing no longer available.
290 #define kmemleak_stop(x...) do { \
292 kmemleak_disable(); \
296 * Printing of the objects hex dump to the seq file. The number of lines to be
297 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
298 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
299 * with the object->lock held.
301 static void hex_dump_object(struct seq_file *seq,
302 struct kmemleak_object *object)
304 const u8 *ptr = (const u8 *)object->pointer;
305 int i, len, remaining;
306 unsigned char linebuf[HEX_ROW_SIZE * 5];
308 /* limit the number of lines to HEX_MAX_LINES */
310 min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
312 seq_printf(seq, " hex dump (first %d bytes):\n", len);
313 for (i = 0; i < len; i += HEX_ROW_SIZE) {
314 int linelen = min(remaining, HEX_ROW_SIZE);
316 remaining -= HEX_ROW_SIZE;
317 hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
318 HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
320 seq_printf(seq, " %s\n", linebuf);
325 * Object colors, encoded with count and min_count:
326 * - white - orphan object, not enough references to it (count < min_count)
327 * - gray - not orphan, not marked as false positive (min_count == 0) or
328 * sufficient references to it (count >= min_count)
329 * - black - ignore, it doesn't contain references (e.g. text section)
330 * (min_count == -1). No function defined for this color.
331 * Newly created objects don't have any color assigned (object->count == -1)
332 * before the next memory scan when they become white.
334 static bool color_white(const struct kmemleak_object *object)
336 return object->count != KMEMLEAK_BLACK &&
337 object->count < object->min_count;
340 static bool color_gray(const struct kmemleak_object *object)
342 return object->min_count != KMEMLEAK_BLACK &&
343 object->count >= object->min_count;
347 * Objects are considered unreferenced only if their color is white, they have
348 * not be deleted and have a minimum age to avoid false positives caused by
349 * pointers temporarily stored in CPU registers.
351 static bool unreferenced_object(struct kmemleak_object *object)
353 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
354 time_before_eq(object->jiffies + jiffies_min_age,
359 * Printing of the unreferenced objects information to the seq file. The
360 * print_unreferenced function must be called with the object->lock held.
362 static void print_unreferenced(struct seq_file *seq,
363 struct kmemleak_object *object)
366 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
368 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
369 object->pointer, object->size);
370 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
371 object->comm, object->pid, object->jiffies,
372 msecs_age / 1000, msecs_age % 1000);
373 hex_dump_object(seq, object);
374 seq_printf(seq, " backtrace:\n");
376 for (i = 0; i < object->trace_len; i++) {
377 void *ptr = (void *)object->trace[i];
378 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
383 * Print the kmemleak_object information. This function is used mainly for
384 * debugging special cases when kmemleak operations. It must be called with
385 * the object->lock held.
387 static void dump_object_info(struct kmemleak_object *object)
389 struct stack_trace trace;
391 trace.nr_entries = object->trace_len;
392 trace.entries = object->trace;
394 pr_notice("Object 0x%08lx (size %zu):\n",
395 object->pointer, object->size);
396 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
397 object->comm, object->pid, object->jiffies);
398 pr_notice(" min_count = %d\n", object->min_count);
399 pr_notice(" count = %d\n", object->count);
400 pr_notice(" flags = 0x%lx\n", object->flags);
401 pr_notice(" checksum = %u\n", object->checksum);
402 pr_notice(" backtrace:\n");
403 print_stack_trace(&trace, 4);
407 * Look-up a memory block metadata (kmemleak_object) in the object search
408 * tree based on a pointer value. If alias is 0, only values pointing to the
409 * beginning of the memory block are allowed. The kmemleak_lock must be held
410 * when calling this function.
412 static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
414 struct rb_node *rb = object_tree_root.rb_node;
417 struct kmemleak_object *object =
418 rb_entry(rb, struct kmemleak_object, rb_node);
419 if (ptr < object->pointer)
420 rb = object->rb_node.rb_left;
421 else if (object->pointer + object->size <= ptr)
422 rb = object->rb_node.rb_right;
423 else if (object->pointer == ptr || alias)
426 kmemleak_warn("Found object by alias at 0x%08lx\n",
428 dump_object_info(object);
436 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
437 * that once an object's use_count reached 0, the RCU freeing was already
438 * registered and the object should no longer be used. This function must be
439 * called under the protection of rcu_read_lock().
441 static int get_object(struct kmemleak_object *object)
443 return atomic_inc_not_zero(&object->use_count);
447 * RCU callback to free a kmemleak_object.
449 static void free_object_rcu(struct rcu_head *rcu)
451 struct hlist_node *tmp;
452 struct kmemleak_scan_area *area;
453 struct kmemleak_object *object =
454 container_of(rcu, struct kmemleak_object, rcu);
457 * Once use_count is 0 (guaranteed by put_object), there is no other
458 * code accessing this object, hence no need for locking.
460 hlist_for_each_entry_safe(area, tmp, &object->area_list, node) {
461 hlist_del(&area->node);
462 kmem_cache_free(scan_area_cache, area);
464 kmem_cache_free(object_cache, object);
468 * Decrement the object use_count. Once the count is 0, free the object using
469 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
470 * delete_object() path, the delayed RCU freeing ensures that there is no
471 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
474 static void put_object(struct kmemleak_object *object)
476 if (!atomic_dec_and_test(&object->use_count))
479 /* should only get here after delete_object was called */
480 WARN_ON(object->flags & OBJECT_ALLOCATED);
482 call_rcu(&object->rcu, free_object_rcu);
486 * Look up an object in the object search tree and increase its use_count.
488 static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
491 struct kmemleak_object *object = NULL;
494 read_lock_irqsave(&kmemleak_lock, flags);
495 object = lookup_object(ptr, alias);
496 read_unlock_irqrestore(&kmemleak_lock, flags);
498 /* check whether the object is still available */
499 if (object && !get_object(object))
507 * Look up an object in the object search tree and remove it from both
508 * object_tree_root and object_list. The returned object's use_count should be
509 * at least 1, as initially set by create_object().
511 static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int alias)
514 struct kmemleak_object *object;
516 write_lock_irqsave(&kmemleak_lock, flags);
517 object = lookup_object(ptr, alias);
519 rb_erase(&object->rb_node, &object_tree_root);
520 list_del_rcu(&object->object_list);
522 write_unlock_irqrestore(&kmemleak_lock, flags);
528 * Save stack trace to the given array of MAX_TRACE size.
530 static int __save_stack_trace(unsigned long *trace)
532 struct stack_trace stack_trace;
534 stack_trace.max_entries = MAX_TRACE;
535 stack_trace.nr_entries = 0;
536 stack_trace.entries = trace;
537 stack_trace.skip = 2;
538 save_stack_trace(&stack_trace);
540 return stack_trace.nr_entries;
544 * Create the metadata (struct kmemleak_object) corresponding to an allocated
545 * memory block and add it to the object_list and object_tree_root.
547 static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
548 int min_count, gfp_t gfp)
551 struct kmemleak_object *object, *parent;
552 struct rb_node **link, *rb_parent;
554 object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
556 pr_warning("Cannot allocate a kmemleak_object structure\n");
561 INIT_LIST_HEAD(&object->object_list);
562 INIT_LIST_HEAD(&object->gray_list);
563 INIT_HLIST_HEAD(&object->area_list);
564 spin_lock_init(&object->lock);
565 atomic_set(&object->use_count, 1);
566 object->flags = OBJECT_ALLOCATED;
567 object->pointer = ptr;
569 object->min_count = min_count;
570 object->count = 0; /* white color initially */
571 object->jiffies = jiffies;
572 object->checksum = 0;
574 /* task information */
577 strncpy(object->comm, "hardirq", sizeof(object->comm));
578 } else if (in_softirq()) {
580 strncpy(object->comm, "softirq", sizeof(object->comm));
582 object->pid = current->pid;
584 * There is a small chance of a race with set_task_comm(),
585 * however using get_task_comm() here may cause locking
586 * dependency issues with current->alloc_lock. In the worst
587 * case, the command line is not correct.
589 strncpy(object->comm, current->comm, sizeof(object->comm));
592 /* kernel backtrace */
593 object->trace_len = __save_stack_trace(object->trace);
595 write_lock_irqsave(&kmemleak_lock, flags);
597 min_addr = min(min_addr, ptr);
598 max_addr = max(max_addr, ptr + size);
599 link = &object_tree_root.rb_node;
603 parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
604 if (ptr + size <= parent->pointer)
605 link = &parent->rb_node.rb_left;
606 else if (parent->pointer + parent->size <= ptr)
607 link = &parent->rb_node.rb_right;
609 kmemleak_stop("Cannot insert 0x%lx into the object "
610 "search tree (overlaps existing)\n",
613 * No need for parent->lock here since "parent" cannot
614 * be freed while the kmemleak_lock is held.
616 dump_object_info(parent);
617 kmem_cache_free(object_cache, object);
622 rb_link_node(&object->rb_node, rb_parent, link);
623 rb_insert_color(&object->rb_node, &object_tree_root);
625 list_add_tail_rcu(&object->object_list, &object_list);
627 write_unlock_irqrestore(&kmemleak_lock, flags);
632 * Mark the object as not allocated and schedule RCU freeing via put_object().
634 static void __delete_object(struct kmemleak_object *object)
638 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
639 WARN_ON(atomic_read(&object->use_count) < 1);
642 * Locking here also ensures that the corresponding memory block
643 * cannot be freed when it is being scanned.
645 spin_lock_irqsave(&object->lock, flags);
646 object->flags &= ~OBJECT_ALLOCATED;
647 spin_unlock_irqrestore(&object->lock, flags);
652 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
655 static void delete_object_full(unsigned long ptr)
657 struct kmemleak_object *object;
659 object = find_and_remove_object(ptr, 0);
662 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
667 __delete_object(object);
671 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
672 * delete it. If the memory block is partially freed, the function may create
673 * additional metadata for the remaining parts of the block.
675 static void delete_object_part(unsigned long ptr, size_t size)
677 struct kmemleak_object *object;
678 unsigned long start, end;
680 object = find_and_remove_object(ptr, 1);
683 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
684 "(size %zu)\n", ptr, size);
690 * Create one or two objects that may result from the memory block
691 * split. Note that partial freeing is only done by free_bootmem() and
692 * this happens before kmemleak_init() is called. The path below is
693 * only executed during early log recording in kmemleak_init(), so
694 * GFP_KERNEL is enough.
696 start = object->pointer;
697 end = object->pointer + object->size;
699 create_object(start, ptr - start, object->min_count,
701 if (ptr + size < end)
702 create_object(ptr + size, end - ptr - size, object->min_count,
705 __delete_object(object);
708 static void __paint_it(struct kmemleak_object *object, int color)
710 object->min_count = color;
711 if (color == KMEMLEAK_BLACK)
712 object->flags |= OBJECT_NO_SCAN;
715 static void paint_it(struct kmemleak_object *object, int color)
719 spin_lock_irqsave(&object->lock, flags);
720 __paint_it(object, color);
721 spin_unlock_irqrestore(&object->lock, flags);
724 static void paint_ptr(unsigned long ptr, int color)
726 struct kmemleak_object *object;
728 object = find_and_get_object(ptr, 0);
730 kmemleak_warn("Trying to color unknown object "
731 "at 0x%08lx as %s\n", ptr,
732 (color == KMEMLEAK_GREY) ? "Grey" :
733 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
736 paint_it(object, color);
741 * Mark an object permanently as gray-colored so that it can no longer be
742 * reported as a leak. This is used in general to mark a false positive.
744 static void make_gray_object(unsigned long ptr)
746 paint_ptr(ptr, KMEMLEAK_GREY);
750 * Mark the object as black-colored so that it is ignored from scans and
753 static void make_black_object(unsigned long ptr)
755 paint_ptr(ptr, KMEMLEAK_BLACK);
759 * Add a scanning area to the object. If at least one such area is added,
760 * kmemleak will only scan these ranges rather than the whole memory block.
762 static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
765 struct kmemleak_object *object;
766 struct kmemleak_scan_area *area;
768 object = find_and_get_object(ptr, 1);
770 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
775 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
777 pr_warning("Cannot allocate a scan area\n");
781 spin_lock_irqsave(&object->lock, flags);
782 if (size == SIZE_MAX) {
783 size = object->pointer + object->size - ptr;
784 } else if (ptr + size > object->pointer + object->size) {
785 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
786 dump_object_info(object);
787 kmem_cache_free(scan_area_cache, area);
791 INIT_HLIST_NODE(&area->node);
795 hlist_add_head(&area->node, &object->area_list);
797 spin_unlock_irqrestore(&object->lock, flags);
803 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
804 * pointer. Such object will not be scanned by kmemleak but references to it
807 static void object_no_scan(unsigned long ptr)
810 struct kmemleak_object *object;
812 object = find_and_get_object(ptr, 0);
814 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
818 spin_lock_irqsave(&object->lock, flags);
819 object->flags |= OBJECT_NO_SCAN;
820 spin_unlock_irqrestore(&object->lock, flags);
825 * Log an early kmemleak_* call to the early_log buffer. These calls will be
826 * processed later once kmemleak is fully initialized.
828 static void __init log_early(int op_type, const void *ptr, size_t size,
832 struct early_log *log;
834 if (kmemleak_error) {
835 /* kmemleak stopped recording, just count the requests */
840 if (crt_early_log >= ARRAY_SIZE(early_log)) {
847 * There is no need for locking since the kernel is still in UP mode
848 * at this stage. Disabling the IRQs is enough.
850 local_irq_save(flags);
851 log = &early_log[crt_early_log];
852 log->op_type = op_type;
855 log->min_count = min_count;
856 log->trace_len = __save_stack_trace(log->trace);
858 local_irq_restore(flags);
862 * Log an early allocated block and populate the stack trace.
864 static void early_alloc(struct early_log *log)
866 struct kmemleak_object *object;
870 if (!kmemleak_enabled || !log->ptr || IS_ERR(log->ptr))
874 * RCU locking needed to ensure object is not freed via put_object().
877 object = create_object((unsigned long)log->ptr, log->size,
878 log->min_count, GFP_ATOMIC);
881 spin_lock_irqsave(&object->lock, flags);
882 for (i = 0; i < log->trace_len; i++)
883 object->trace[i] = log->trace[i];
884 object->trace_len = log->trace_len;
885 spin_unlock_irqrestore(&object->lock, flags);
891 * Log an early allocated block and populate the stack trace.
893 static void early_alloc_percpu(struct early_log *log)
896 const void __percpu *ptr = log->ptr;
898 for_each_possible_cpu(cpu) {
899 log->ptr = per_cpu_ptr(ptr, cpu);
905 * kmemleak_alloc - register a newly allocated object
906 * @ptr: pointer to beginning of the object
907 * @size: size of the object
908 * @min_count: minimum number of references to this object. If during memory
909 * scanning a number of references less than @min_count is found,
910 * the object is reported as a memory leak. If @min_count is 0,
911 * the object is never reported as a leak. If @min_count is -1,
912 * the object is ignored (not scanned and not reported as a leak)
913 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
915 * This function is called from the kernel allocators when a new object
916 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
918 void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
921 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
923 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
924 create_object((unsigned long)ptr, size, min_count, gfp);
925 else if (kmemleak_early_log)
926 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
928 EXPORT_SYMBOL_GPL(kmemleak_alloc);
931 * kmemleak_alloc_percpu - register a newly allocated __percpu object
932 * @ptr: __percpu pointer to beginning of the object
933 * @size: size of the object
934 * @gfp: flags used for kmemleak internal memory allocations
936 * This function is called from the kernel percpu allocator when a new object
937 * (memory block) is allocated (alloc_percpu).
939 void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size,
944 pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
947 * Percpu allocations are only scanned and not reported as leaks
948 * (min_count is set to 0).
950 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
951 for_each_possible_cpu(cpu)
952 create_object((unsigned long)per_cpu_ptr(ptr, cpu),
954 else if (kmemleak_early_log)
955 log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
957 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
960 * kmemleak_free - unregister a previously registered object
961 * @ptr: pointer to beginning of the object
963 * This function is called from the kernel allocators when an object (memory
964 * block) is freed (kmem_cache_free, kfree, vfree etc.).
966 void __ref kmemleak_free(const void *ptr)
968 pr_debug("%s(0x%p)\n", __func__, ptr);
970 if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
971 delete_object_full((unsigned long)ptr);
972 else if (kmemleak_early_log)
973 log_early(KMEMLEAK_FREE, ptr, 0, 0);
975 EXPORT_SYMBOL_GPL(kmemleak_free);
978 * kmemleak_free_part - partially unregister a previously registered object
979 * @ptr: pointer to the beginning or inside the object. This also
980 * represents the start of the range to be freed
981 * @size: size to be unregistered
983 * This function is called when only a part of a memory block is freed
984 * (usually from the bootmem allocator).
986 void __ref kmemleak_free_part(const void *ptr, size_t size)
988 pr_debug("%s(0x%p)\n", __func__, ptr);
990 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
991 delete_object_part((unsigned long)ptr, size);
992 else if (kmemleak_early_log)
993 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
995 EXPORT_SYMBOL_GPL(kmemleak_free_part);
998 * kmemleak_free_percpu - unregister a previously registered __percpu object
999 * @ptr: __percpu pointer to beginning of the object
1001 * This function is called from the kernel percpu allocator when an object
1002 * (memory block) is freed (free_percpu).
1004 void __ref kmemleak_free_percpu(const void __percpu *ptr)
1008 pr_debug("%s(0x%p)\n", __func__, ptr);
1010 if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
1011 for_each_possible_cpu(cpu)
1012 delete_object_full((unsigned long)per_cpu_ptr(ptr,
1014 else if (kmemleak_early_log)
1015 log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
1017 EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
1020 * kmemleak_update_trace - update object allocation stack trace
1021 * @ptr: pointer to beginning of the object
1023 * Override the object allocation stack trace for cases where the actual
1024 * allocation place is not always useful.
1026 void __ref kmemleak_update_trace(const void *ptr)
1028 struct kmemleak_object *object;
1029 unsigned long flags;
1031 pr_debug("%s(0x%p)\n", __func__, ptr);
1033 if (!kmemleak_enabled || IS_ERR_OR_NULL(ptr))
1036 object = find_and_get_object((unsigned long)ptr, 1);
1039 kmemleak_warn("Updating stack trace for unknown object at %p\n",
1045 spin_lock_irqsave(&object->lock, flags);
1046 object->trace_len = __save_stack_trace(object->trace);
1047 spin_unlock_irqrestore(&object->lock, flags);
1051 EXPORT_SYMBOL(kmemleak_update_trace);
1054 * kmemleak_not_leak - mark an allocated object as false positive
1055 * @ptr: pointer to beginning of the object
1057 * Calling this function on an object will cause the memory block to no longer
1058 * be reported as leak and always be scanned.
1060 void __ref kmemleak_not_leak(const void *ptr)
1062 pr_debug("%s(0x%p)\n", __func__, ptr);
1064 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1065 make_gray_object((unsigned long)ptr);
1066 else if (kmemleak_early_log)
1067 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
1069 EXPORT_SYMBOL(kmemleak_not_leak);
1072 * kmemleak_ignore - ignore an allocated object
1073 * @ptr: pointer to beginning of the object
1075 * Calling this function on an object will cause the memory block to be
1076 * ignored (not scanned and not reported as a leak). This is usually done when
1077 * it is known that the corresponding block is not a leak and does not contain
1078 * any references to other allocated memory blocks.
1080 void __ref kmemleak_ignore(const void *ptr)
1082 pr_debug("%s(0x%p)\n", __func__, ptr);
1084 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1085 make_black_object((unsigned long)ptr);
1086 else if (kmemleak_early_log)
1087 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
1089 EXPORT_SYMBOL(kmemleak_ignore);
1092 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1093 * @ptr: pointer to beginning or inside the object. This also
1094 * represents the start of the scan area
1095 * @size: size of the scan area
1096 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1098 * This function is used when it is known that only certain parts of an object
1099 * contain references to other objects. Kmemleak will only scan these areas
1100 * reducing the number false negatives.
1102 void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
1104 pr_debug("%s(0x%p)\n", __func__, ptr);
1106 if (kmemleak_enabled && ptr && size && !IS_ERR(ptr))
1107 add_scan_area((unsigned long)ptr, size, gfp);
1108 else if (kmemleak_early_log)
1109 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
1111 EXPORT_SYMBOL(kmemleak_scan_area);
1114 * kmemleak_no_scan - do not scan an allocated object
1115 * @ptr: pointer to beginning of the object
1117 * This function notifies kmemleak not to scan the given memory block. Useful
1118 * in situations where it is known that the given object does not contain any
1119 * references to other objects. Kmemleak will not scan such objects reducing
1120 * the number of false negatives.
1122 void __ref kmemleak_no_scan(const void *ptr)
1124 pr_debug("%s(0x%p)\n", __func__, ptr);
1126 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1127 object_no_scan((unsigned long)ptr);
1128 else if (kmemleak_early_log)
1129 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
1131 EXPORT_SYMBOL(kmemleak_no_scan);
1134 * Update an object's checksum and return true if it was modified.
1136 static bool update_checksum(struct kmemleak_object *object)
1138 u32 old_csum = object->checksum;
1140 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
1143 kasan_disable_current();
1144 object->checksum = crc32(0, (void *)object->pointer, object->size);
1145 kasan_enable_current();
1147 return object->checksum != old_csum;
1151 * Memory scanning is a long process and it needs to be interruptable. This
1152 * function checks whether such interrupt condition occurred.
1154 static int scan_should_stop(void)
1156 if (!kmemleak_enabled)
1160 * This function may be called from either process or kthread context,
1161 * hence the need to check for both stop conditions.
1164 return signal_pending(current);
1166 return kthread_should_stop();
1172 * Scan a memory block (exclusive range) for valid pointers and add those
1173 * found to the gray list.
1175 static void scan_block(void *_start, void *_end,
1176 struct kmemleak_object *scanned)
1179 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1180 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1181 unsigned long flags;
1183 read_lock_irqsave(&kmemleak_lock, flags);
1184 for (ptr = start; ptr < end; ptr++) {
1185 struct kmemleak_object *object;
1186 unsigned long pointer;
1188 if (scan_should_stop())
1191 /* don't scan uninitialized memory */
1192 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1196 kasan_disable_current();
1198 kasan_enable_current();
1200 if (pointer < min_addr || pointer >= max_addr)
1204 * No need for get_object() here since we hold kmemleak_lock.
1205 * object->use_count cannot be dropped to 0 while the object
1206 * is still present in object_tree_root and object_list
1207 * (with updates protected by kmemleak_lock).
1209 object = lookup_object(pointer, 1);
1212 if (object == scanned)
1213 /* self referenced, ignore */
1217 * Avoid the lockdep recursive warning on object->lock being
1218 * previously acquired in scan_object(). These locks are
1219 * enclosed by scan_mutex.
1221 spin_lock_nested(&object->lock, SINGLE_DEPTH_NESTING);
1222 if (!color_white(object)) {
1223 /* non-orphan, ignored or new */
1224 spin_unlock(&object->lock);
1229 * Increase the object's reference count (number of pointers
1230 * to the memory block). If this count reaches the required
1231 * minimum, the object's color will become gray and it will be
1232 * added to the gray_list.
1235 if (color_gray(object)) {
1236 /* put_object() called when removing from gray_list */
1237 WARN_ON(!get_object(object));
1238 list_add_tail(&object->gray_list, &gray_list);
1240 spin_unlock(&object->lock);
1242 read_unlock_irqrestore(&kmemleak_lock, flags);
1246 * Scan a large memory block in MAX_SCAN_SIZE chunks to reduce the latency.
1248 static void scan_large_block(void *start, void *end)
1252 while (start < end) {
1253 next = min(start + MAX_SCAN_SIZE, end);
1254 scan_block(start, next, NULL);
1261 * Scan a memory block corresponding to a kmemleak_object. A condition is
1262 * that object->use_count >= 1.
1264 static void scan_object(struct kmemleak_object *object)
1266 struct kmemleak_scan_area *area;
1267 unsigned long flags;
1270 * Once the object->lock is acquired, the corresponding memory block
1271 * cannot be freed (the same lock is acquired in delete_object).
1273 spin_lock_irqsave(&object->lock, flags);
1274 if (object->flags & OBJECT_NO_SCAN)
1276 if (!(object->flags & OBJECT_ALLOCATED))
1277 /* already freed object */
1279 if (hlist_empty(&object->area_list)) {
1280 void *start = (void *)object->pointer;
1281 void *end = (void *)(object->pointer + object->size);
1285 next = min(start + MAX_SCAN_SIZE, end);
1286 scan_block(start, next, object);
1292 spin_unlock_irqrestore(&object->lock, flags);
1294 spin_lock_irqsave(&object->lock, flags);
1295 } while (object->flags & OBJECT_ALLOCATED);
1297 hlist_for_each_entry(area, &object->area_list, node)
1298 scan_block((void *)area->start,
1299 (void *)(area->start + area->size),
1302 spin_unlock_irqrestore(&object->lock, flags);
1306 * Scan the objects already referenced (gray objects). More objects will be
1307 * referenced and, if there are no memory leaks, all the objects are scanned.
1309 static void scan_gray_list(void)
1311 struct kmemleak_object *object, *tmp;
1314 * The list traversal is safe for both tail additions and removals
1315 * from inside the loop. The kmemleak objects cannot be freed from
1316 * outside the loop because their use_count was incremented.
1318 object = list_entry(gray_list.next, typeof(*object), gray_list);
1319 while (&object->gray_list != &gray_list) {
1322 /* may add new objects to the list */
1323 if (!scan_should_stop())
1324 scan_object(object);
1326 tmp = list_entry(object->gray_list.next, typeof(*object),
1329 /* remove the object from the list and release it */
1330 list_del(&object->gray_list);
1335 WARN_ON(!list_empty(&gray_list));
1339 * Scan data sections and all the referenced memory blocks allocated via the
1340 * kernel's standard allocators. This function must be called with the
1343 static void kmemleak_scan(void)
1345 unsigned long flags;
1346 struct kmemleak_object *object;
1350 jiffies_last_scan = jiffies;
1352 /* prepare the kmemleak_object's */
1354 list_for_each_entry_rcu(object, &object_list, object_list) {
1355 spin_lock_irqsave(&object->lock, flags);
1358 * With a few exceptions there should be a maximum of
1359 * 1 reference to any object at this point.
1361 if (atomic_read(&object->use_count) > 1) {
1362 pr_debug("object->use_count = %d\n",
1363 atomic_read(&object->use_count));
1364 dump_object_info(object);
1367 /* reset the reference count (whiten the object) */
1369 if (color_gray(object) && get_object(object))
1370 list_add_tail(&object->gray_list, &gray_list);
1372 spin_unlock_irqrestore(&object->lock, flags);
1376 /* data/bss scanning */
1377 scan_large_block(_sdata, _edata);
1378 scan_large_block(__bss_start, __bss_stop);
1381 /* per-cpu sections scanning */
1382 for_each_possible_cpu(i)
1383 scan_large_block(__per_cpu_start + per_cpu_offset(i),
1384 __per_cpu_end + per_cpu_offset(i));
1388 * Struct page scanning for each node.
1391 for_each_online_node(i) {
1392 unsigned long start_pfn = node_start_pfn(i);
1393 unsigned long end_pfn = node_end_pfn(i);
1396 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1399 if (!pfn_valid(pfn))
1401 page = pfn_to_page(pfn);
1402 /* only scan if page is in use */
1403 if (page_count(page) == 0)
1405 scan_block(page, page + 1, NULL);
1411 * Scanning the task stacks (may introduce false negatives).
1413 if (kmemleak_stack_scan) {
1414 struct task_struct *p, *g;
1416 read_lock(&tasklist_lock);
1417 do_each_thread(g, p) {
1418 scan_block(task_stack_page(p), task_stack_page(p) +
1420 } while_each_thread(g, p);
1421 read_unlock(&tasklist_lock);
1425 * Scan the objects already referenced from the sections scanned
1431 * Check for new or unreferenced objects modified since the previous
1432 * scan and color them gray until the next scan.
1435 list_for_each_entry_rcu(object, &object_list, object_list) {
1436 spin_lock_irqsave(&object->lock, flags);
1437 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1438 && update_checksum(object) && get_object(object)) {
1439 /* color it gray temporarily */
1440 object->count = object->min_count;
1441 list_add_tail(&object->gray_list, &gray_list);
1443 spin_unlock_irqrestore(&object->lock, flags);
1448 * Re-scan the gray list for modified unreferenced objects.
1453 * If scanning was stopped do not report any new unreferenced objects.
1455 if (scan_should_stop())
1459 * Scanning result reporting.
1462 list_for_each_entry_rcu(object, &object_list, object_list) {
1463 spin_lock_irqsave(&object->lock, flags);
1464 if (unreferenced_object(object) &&
1465 !(object->flags & OBJECT_REPORTED)) {
1466 object->flags |= OBJECT_REPORTED;
1469 spin_unlock_irqrestore(&object->lock, flags);
1474 kmemleak_found_leaks = true;
1476 pr_info("%d new suspected memory leaks (see "
1477 "/sys/kernel/debug/kmemleak)\n", new_leaks);
1483 * Thread function performing automatic memory scanning. Unreferenced objects
1484 * at the end of a memory scan are reported but only the first time.
1486 static int kmemleak_scan_thread(void *arg)
1488 static int first_run = 1;
1490 pr_info("Automatic memory scanning thread started\n");
1491 set_user_nice(current, 10);
1494 * Wait before the first scan to allow the system to fully initialize.
1498 ssleep(SECS_FIRST_SCAN);
1501 while (!kthread_should_stop()) {
1502 signed long timeout = jiffies_scan_wait;
1504 mutex_lock(&scan_mutex);
1506 mutex_unlock(&scan_mutex);
1508 /* wait before the next scan */
1509 while (timeout && !kthread_should_stop())
1510 timeout = schedule_timeout_interruptible(timeout);
1513 pr_info("Automatic memory scanning thread ended\n");
1519 * Start the automatic memory scanning thread. This function must be called
1520 * with the scan_mutex held.
1522 static void start_scan_thread(void)
1526 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1527 if (IS_ERR(scan_thread)) {
1528 pr_warning("Failed to create the scan thread\n");
1534 * Stop the automatic memory scanning thread. This function must be called
1535 * with the scan_mutex held.
1537 static void stop_scan_thread(void)
1540 kthread_stop(scan_thread);
1546 * Iterate over the object_list and return the first valid object at or after
1547 * the required position with its use_count incremented. The function triggers
1548 * a memory scanning when the pos argument points to the first position.
1550 static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1552 struct kmemleak_object *object;
1556 err = mutex_lock_interruptible(&scan_mutex);
1558 return ERR_PTR(err);
1561 list_for_each_entry_rcu(object, &object_list, object_list) {
1564 if (get_object(object))
1573 * Return the next object in the object_list. The function decrements the
1574 * use_count of the previous object and increases that of the next one.
1576 static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1578 struct kmemleak_object *prev_obj = v;
1579 struct kmemleak_object *next_obj = NULL;
1580 struct kmemleak_object *obj = prev_obj;
1584 list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
1585 if (get_object(obj)) {
1591 put_object(prev_obj);
1596 * Decrement the use_count of the last object required, if any.
1598 static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1602 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1603 * waiting was interrupted, so only release it if !IS_ERR.
1606 mutex_unlock(&scan_mutex);
1613 * Print the information for an unreferenced object to the seq file.
1615 static int kmemleak_seq_show(struct seq_file *seq, void *v)
1617 struct kmemleak_object *object = v;
1618 unsigned long flags;
1620 spin_lock_irqsave(&object->lock, flags);
1621 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
1622 print_unreferenced(seq, object);
1623 spin_unlock_irqrestore(&object->lock, flags);
1627 static const struct seq_operations kmemleak_seq_ops = {
1628 .start = kmemleak_seq_start,
1629 .next = kmemleak_seq_next,
1630 .stop = kmemleak_seq_stop,
1631 .show = kmemleak_seq_show,
1634 static int kmemleak_open(struct inode *inode, struct file *file)
1636 return seq_open(file, &kmemleak_seq_ops);
1639 static int dump_str_object_info(const char *str)
1641 unsigned long flags;
1642 struct kmemleak_object *object;
1645 if (kstrtoul(str, 0, &addr))
1647 object = find_and_get_object(addr, 0);
1649 pr_info("Unknown object at 0x%08lx\n", addr);
1653 spin_lock_irqsave(&object->lock, flags);
1654 dump_object_info(object);
1655 spin_unlock_irqrestore(&object->lock, flags);
1662 * We use grey instead of black to ensure we can do future scans on the same
1663 * objects. If we did not do future scans these black objects could
1664 * potentially contain references to newly allocated objects in the future and
1665 * we'd end up with false positives.
1667 static void kmemleak_clear(void)
1669 struct kmemleak_object *object;
1670 unsigned long flags;
1673 list_for_each_entry_rcu(object, &object_list, object_list) {
1674 spin_lock_irqsave(&object->lock, flags);
1675 if ((object->flags & OBJECT_REPORTED) &&
1676 unreferenced_object(object))
1677 __paint_it(object, KMEMLEAK_GREY);
1678 spin_unlock_irqrestore(&object->lock, flags);
1682 kmemleak_found_leaks = false;
1685 static void __kmemleak_do_cleanup(void);
1688 * File write operation to configure kmemleak at run-time. The following
1689 * commands can be written to the /sys/kernel/debug/kmemleak file:
1690 * off - disable kmemleak (irreversible)
1691 * stack=on - enable the task stacks scanning
1692 * stack=off - disable the tasks stacks scanning
1693 * scan=on - start the automatic memory scanning thread
1694 * scan=off - stop the automatic memory scanning thread
1695 * scan=... - set the automatic memory scanning period in seconds (0 to
1697 * scan - trigger a memory scan
1698 * clear - mark all current reported unreferenced kmemleak objects as
1699 * grey to ignore printing them, or free all kmemleak objects
1700 * if kmemleak has been disabled.
1701 * dump=... - dump information about the object found at the given address
1703 static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1704 size_t size, loff_t *ppos)
1710 buf_size = min(size, (sizeof(buf) - 1));
1711 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1715 ret = mutex_lock_interruptible(&scan_mutex);
1719 if (strncmp(buf, "clear", 5) == 0) {
1720 if (kmemleak_enabled)
1723 __kmemleak_do_cleanup();
1727 if (!kmemleak_enabled) {
1732 if (strncmp(buf, "off", 3) == 0)
1734 else if (strncmp(buf, "stack=on", 8) == 0)
1735 kmemleak_stack_scan = 1;
1736 else if (strncmp(buf, "stack=off", 9) == 0)
1737 kmemleak_stack_scan = 0;
1738 else if (strncmp(buf, "scan=on", 7) == 0)
1739 start_scan_thread();
1740 else if (strncmp(buf, "scan=off", 8) == 0)
1742 else if (strncmp(buf, "scan=", 5) == 0) {
1745 ret = kstrtoul(buf + 5, 0, &secs);
1750 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1751 start_scan_thread();
1753 } else if (strncmp(buf, "scan", 4) == 0)
1755 else if (strncmp(buf, "dump=", 5) == 0)
1756 ret = dump_str_object_info(buf + 5);
1761 mutex_unlock(&scan_mutex);
1765 /* ignore the rest of the buffer, only one command at a time */
1770 static const struct file_operations kmemleak_fops = {
1771 .owner = THIS_MODULE,
1772 .open = kmemleak_open,
1774 .write = kmemleak_write,
1775 .llseek = seq_lseek,
1776 .release = seq_release,
1779 static void __kmemleak_do_cleanup(void)
1781 struct kmemleak_object *object;
1784 list_for_each_entry_rcu(object, &object_list, object_list)
1785 delete_object_full(object->pointer);
1790 * Stop the memory scanning thread and free the kmemleak internal objects if
1791 * no previous scan thread (otherwise, kmemleak may still have some useful
1792 * information on memory leaks).
1794 static void kmemleak_do_cleanup(struct work_struct *work)
1799 * Once the scan thread has stopped, it is safe to no longer track
1800 * object freeing. Ordering of the scan thread stopping and the memory
1801 * accesses below is guaranteed by the kthread_stop() function.
1803 kmemleak_free_enabled = 0;
1805 if (!kmemleak_found_leaks)
1806 __kmemleak_do_cleanup();
1808 pr_info("Kmemleak disabled without freeing internal data. "
1809 "Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\"\n");
1812 static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
1815 * Disable kmemleak. No memory allocation/freeing will be traced once this
1816 * function is called. Disabling kmemleak is an irreversible operation.
1818 static void kmemleak_disable(void)
1820 /* atomically check whether it was already invoked */
1821 if (cmpxchg(&kmemleak_error, 0, 1))
1824 /* stop any memory operation tracing */
1825 kmemleak_enabled = 0;
1827 /* check whether it is too early for a kernel thread */
1828 if (kmemleak_initialized)
1829 schedule_work(&cleanup_work);
1831 kmemleak_free_enabled = 0;
1833 pr_info("Kernel memory leak detector disabled\n");
1837 * Allow boot-time kmemleak disabling (enabled by default).
1839 static int kmemleak_boot_config(char *str)
1843 if (strcmp(str, "off") == 0)
1845 else if (strcmp(str, "on") == 0)
1846 kmemleak_skip_disable = 1;
1851 early_param("kmemleak", kmemleak_boot_config);
1853 static void __init print_log_trace(struct early_log *log)
1855 struct stack_trace trace;
1857 trace.nr_entries = log->trace_len;
1858 trace.entries = log->trace;
1860 pr_notice("Early log backtrace:\n");
1861 print_stack_trace(&trace, 2);
1865 * Kmemleak initialization.
1867 void __init kmemleak_init(void)
1870 unsigned long flags;
1872 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1873 if (!kmemleak_skip_disable) {
1874 kmemleak_early_log = 0;
1880 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1881 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1883 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1884 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1886 if (crt_early_log > ARRAY_SIZE(early_log))
1887 pr_warning("Early log buffer exceeded (%d), please increase "
1888 "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log);
1890 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1891 local_irq_save(flags);
1892 kmemleak_early_log = 0;
1893 if (kmemleak_error) {
1894 local_irq_restore(flags);
1897 kmemleak_enabled = 1;
1898 kmemleak_free_enabled = 1;
1900 local_irq_restore(flags);
1903 * This is the point where tracking allocations is safe. Automatic
1904 * scanning is started during the late initcall. Add the early logged
1905 * callbacks to the kmemleak infrastructure.
1907 for (i = 0; i < crt_early_log; i++) {
1908 struct early_log *log = &early_log[i];
1910 switch (log->op_type) {
1911 case KMEMLEAK_ALLOC:
1914 case KMEMLEAK_ALLOC_PERCPU:
1915 early_alloc_percpu(log);
1918 kmemleak_free(log->ptr);
1920 case KMEMLEAK_FREE_PART:
1921 kmemleak_free_part(log->ptr, log->size);
1923 case KMEMLEAK_FREE_PERCPU:
1924 kmemleak_free_percpu(log->ptr);
1926 case KMEMLEAK_NOT_LEAK:
1927 kmemleak_not_leak(log->ptr);
1929 case KMEMLEAK_IGNORE:
1930 kmemleak_ignore(log->ptr);
1932 case KMEMLEAK_SCAN_AREA:
1933 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
1935 case KMEMLEAK_NO_SCAN:
1936 kmemleak_no_scan(log->ptr);
1939 kmemleak_warn("Unknown early log operation: %d\n",
1943 if (kmemleak_warning) {
1944 print_log_trace(log);
1945 kmemleak_warning = 0;
1951 * Late initialization function.
1953 static int __init kmemleak_late_init(void)
1955 struct dentry *dentry;
1957 kmemleak_initialized = 1;
1959 if (kmemleak_error) {
1961 * Some error occurred and kmemleak was disabled. There is a
1962 * small chance that kmemleak_disable() was called immediately
1963 * after setting kmemleak_initialized and we may end up with
1964 * two clean-up threads but serialized by scan_mutex.
1966 schedule_work(&cleanup_work);
1970 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1973 pr_warning("Failed to create the debugfs kmemleak file\n");
1974 mutex_lock(&scan_mutex);
1975 start_scan_thread();
1976 mutex_unlock(&scan_mutex);
1978 pr_info("Kernel memory leak detector initialized\n");
1982 late_initcall(kmemleak_late_init);