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 should only be acquired/nested in the following order:
58 * scan_mutex -> object->lock -> other_object->lock (SINGLE_DEPTH_NESTING)
61 * The kmemleak_object structures have a use_count incremented or decremented
62 * using the get_object()/put_object() functions. When the use_count becomes
63 * 0, this count can no longer be incremented and put_object() schedules the
64 * kmemleak_object freeing via an RCU callback. All calls to the get_object()
65 * function must be protected by rcu_read_lock() to avoid accessing a freed
69 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
71 #include <linux/init.h>
72 #include <linux/kernel.h>
73 #include <linux/list.h>
74 #include <linux/sched.h>
75 #include <linux/jiffies.h>
76 #include <linux/delay.h>
77 #include <linux/export.h>
78 #include <linux/kthread.h>
79 #include <linux/rbtree.h>
81 #include <linux/debugfs.h>
82 #include <linux/seq_file.h>
83 #include <linux/cpumask.h>
84 #include <linux/spinlock.h>
85 #include <linux/mutex.h>
86 #include <linux/rcupdate.h>
87 #include <linux/stacktrace.h>
88 #include <linux/cache.h>
89 #include <linux/percpu.h>
90 #include <linux/hardirq.h>
91 #include <linux/mmzone.h>
92 #include <linux/slab.h>
93 #include <linux/thread_info.h>
94 #include <linux/err.h>
95 #include <linux/uaccess.h>
96 #include <linux/string.h>
97 #include <linux/nodemask.h>
99 #include <linux/workqueue.h>
100 #include <linux/crc32.h>
102 #include <asm/sections.h>
103 #include <asm/processor.h>
104 #include <linux/atomic.h>
106 #include <linux/kasan.h>
107 #include <linux/kmemcheck.h>
108 #include <linux/kmemleak.h>
109 #include <linux/memory_hotplug.h>
112 * Kmemleak configuration and common defines.
114 #define MAX_TRACE 16 /* stack trace length */
115 #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
116 #define SECS_FIRST_SCAN 60 /* delay before the first scan */
117 #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
118 #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
120 #define BYTES_PER_POINTER sizeof(void *)
122 /* GFP bitmask for kmemleak internal allocations */
123 #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC | \
124 __GFP_NOACCOUNT)) | \
125 __GFP_NORETRY | __GFP_NOMEMALLOC | \
128 /* scanning area inside a memory block */
129 struct kmemleak_scan_area {
130 struct hlist_node node;
135 #define KMEMLEAK_GREY 0
136 #define KMEMLEAK_BLACK -1
139 * Structure holding the metadata for each allocated memory block.
140 * Modifications to such objects should be made while holding the
141 * object->lock. Insertions or deletions from object_list, gray_list or
142 * rb_node are already protected by the corresponding locks or mutex (see
143 * the notes on locking above). These objects are reference-counted
144 * (use_count) and freed using the RCU mechanism.
146 struct kmemleak_object {
148 unsigned long flags; /* object status flags */
149 struct list_head object_list;
150 struct list_head gray_list;
151 struct rb_node rb_node;
152 struct rcu_head rcu; /* object_list lockless traversal */
153 /* object usage count; object freed when use_count == 0 */
155 unsigned long pointer;
157 /* minimum number of a pointers found before it is considered leak */
159 /* the total number of pointers found pointing to this object */
161 /* checksum for detecting modified objects */
163 /* memory ranges to be scanned inside an object (empty for all) */
164 struct hlist_head area_list;
165 unsigned long trace[MAX_TRACE];
166 unsigned int trace_len;
167 unsigned long jiffies; /* creation timestamp */
168 pid_t pid; /* pid of the current task */
169 char comm[TASK_COMM_LEN]; /* executable name */
172 /* flag representing the memory block allocation status */
173 #define OBJECT_ALLOCATED (1 << 0)
174 /* flag set after the first reporting of an unreference object */
175 #define OBJECT_REPORTED (1 << 1)
176 /* flag set to not scan the object */
177 #define OBJECT_NO_SCAN (1 << 2)
179 /* number of bytes to print per line; must be 16 or 32 */
180 #define HEX_ROW_SIZE 16
181 /* number of bytes to print at a time (1, 2, 4, 8) */
182 #define HEX_GROUP_SIZE 1
183 /* include ASCII after the hex output */
185 /* max number of lines to be printed */
186 #define HEX_MAX_LINES 2
188 /* the list of all allocated objects */
189 static LIST_HEAD(object_list);
190 /* the list of gray-colored objects (see color_gray comment below) */
191 static LIST_HEAD(gray_list);
192 /* search tree for object boundaries */
193 static struct rb_root object_tree_root = RB_ROOT;
194 /* rw_lock protecting the access to object_list and object_tree_root */
195 static DEFINE_RWLOCK(kmemleak_lock);
197 /* allocation caches for kmemleak internal data */
198 static struct kmem_cache *object_cache;
199 static struct kmem_cache *scan_area_cache;
201 /* set if tracing memory operations is enabled */
202 static int kmemleak_enabled;
203 /* same as above but only for the kmemleak_free() callback */
204 static int kmemleak_free_enabled;
205 /* set in the late_initcall if there were no errors */
206 static int kmemleak_initialized;
207 /* enables or disables early logging of the memory operations */
208 static int kmemleak_early_log = 1;
209 /* set if a kmemleak warning was issued */
210 static int kmemleak_warning;
211 /* set if a fatal kmemleak error has occurred */
212 static int kmemleak_error;
214 /* minimum and maximum address that may be valid pointers */
215 static unsigned long min_addr = ULONG_MAX;
216 static unsigned long max_addr;
218 static struct task_struct *scan_thread;
219 /* used to avoid reporting of recently allocated objects */
220 static unsigned long jiffies_min_age;
221 static unsigned long jiffies_last_scan;
222 /* delay between automatic memory scannings */
223 static signed long jiffies_scan_wait;
224 /* enables or disables the task stacks scanning */
225 static int kmemleak_stack_scan = 1;
226 /* protects the memory scanning, parameters and debug/kmemleak file access */
227 static DEFINE_MUTEX(scan_mutex);
228 /* setting kmemleak=on, will set this var, skipping the disable */
229 static int kmemleak_skip_disable;
230 /* If there are leaks that can be reported */
231 static bool kmemleak_found_leaks;
234 * Early object allocation/freeing logging. Kmemleak is initialized after the
235 * kernel allocator. However, both the kernel allocator and kmemleak may
236 * allocate memory blocks which need to be tracked. Kmemleak defines an
237 * arbitrary buffer to hold the allocation/freeing information before it is
241 /* kmemleak operation type for early logging */
244 KMEMLEAK_ALLOC_PERCPU,
247 KMEMLEAK_FREE_PERCPU,
255 * Structure holding the information passed to kmemleak callbacks during the
259 int op_type; /* kmemleak operation type */
260 const void *ptr; /* allocated/freed memory block */
261 size_t size; /* memory block size */
262 int min_count; /* minimum reference count */
263 unsigned long trace[MAX_TRACE]; /* stack trace */
264 unsigned int trace_len; /* stack trace length */
267 /* early logging buffer and current position */
268 static struct early_log
269 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
270 static int crt_early_log __initdata;
272 static void kmemleak_disable(void);
275 * Print a warning and dump the stack trace.
277 #define kmemleak_warn(x...) do { \
280 kmemleak_warning = 1; \
284 * Macro invoked when a serious kmemleak condition occurred and cannot be
285 * recovered from. Kmemleak will be disabled and further allocation/freeing
286 * tracing no longer available.
288 #define kmemleak_stop(x...) do { \
290 kmemleak_disable(); \
294 * Printing of the objects hex dump to the seq file. The number of lines to be
295 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
296 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
297 * with the object->lock held.
299 static void hex_dump_object(struct seq_file *seq,
300 struct kmemleak_object *object)
302 const u8 *ptr = (const u8 *)object->pointer;
303 int i, len, remaining;
304 unsigned char linebuf[HEX_ROW_SIZE * 5];
306 /* limit the number of lines to HEX_MAX_LINES */
308 min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
310 seq_printf(seq, " hex dump (first %d bytes):\n", len);
311 for (i = 0; i < len; i += HEX_ROW_SIZE) {
312 int linelen = min(remaining, HEX_ROW_SIZE);
314 remaining -= HEX_ROW_SIZE;
315 hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
316 HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
318 seq_printf(seq, " %s\n", linebuf);
323 * Object colors, encoded with count and min_count:
324 * - white - orphan object, not enough references to it (count < min_count)
325 * - gray - not orphan, not marked as false positive (min_count == 0) or
326 * sufficient references to it (count >= min_count)
327 * - black - ignore, it doesn't contain references (e.g. text section)
328 * (min_count == -1). No function defined for this color.
329 * Newly created objects don't have any color assigned (object->count == -1)
330 * before the next memory scan when they become white.
332 static bool color_white(const struct kmemleak_object *object)
334 return object->count != KMEMLEAK_BLACK &&
335 object->count < object->min_count;
338 static bool color_gray(const struct kmemleak_object *object)
340 return object->min_count != KMEMLEAK_BLACK &&
341 object->count >= object->min_count;
345 * Objects are considered unreferenced only if their color is white, they have
346 * not be deleted and have a minimum age to avoid false positives caused by
347 * pointers temporarily stored in CPU registers.
349 static bool unreferenced_object(struct kmemleak_object *object)
351 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
352 time_before_eq(object->jiffies + jiffies_min_age,
357 * Printing of the unreferenced objects information to the seq file. The
358 * print_unreferenced function must be called with the object->lock held.
360 static void print_unreferenced(struct seq_file *seq,
361 struct kmemleak_object *object)
364 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
366 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
367 object->pointer, object->size);
368 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
369 object->comm, object->pid, object->jiffies,
370 msecs_age / 1000, msecs_age % 1000);
371 hex_dump_object(seq, object);
372 seq_printf(seq, " backtrace:\n");
374 for (i = 0; i < object->trace_len; i++) {
375 void *ptr = (void *)object->trace[i];
376 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
381 * Print the kmemleak_object information. This function is used mainly for
382 * debugging special cases when kmemleak operations. It must be called with
383 * the object->lock held.
385 static void dump_object_info(struct kmemleak_object *object)
387 struct stack_trace trace;
389 trace.nr_entries = object->trace_len;
390 trace.entries = object->trace;
392 pr_notice("Object 0x%08lx (size %zu):\n",
393 object->pointer, object->size);
394 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
395 object->comm, object->pid, object->jiffies);
396 pr_notice(" min_count = %d\n", object->min_count);
397 pr_notice(" count = %d\n", object->count);
398 pr_notice(" flags = 0x%lx\n", object->flags);
399 pr_notice(" checksum = %u\n", object->checksum);
400 pr_notice(" backtrace:\n");
401 print_stack_trace(&trace, 4);
405 * Look-up a memory block metadata (kmemleak_object) in the object search
406 * tree based on a pointer value. If alias is 0, only values pointing to the
407 * beginning of the memory block are allowed. The kmemleak_lock must be held
408 * when calling this function.
410 static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
412 struct rb_node *rb = object_tree_root.rb_node;
415 struct kmemleak_object *object =
416 rb_entry(rb, struct kmemleak_object, rb_node);
417 if (ptr < object->pointer)
418 rb = object->rb_node.rb_left;
419 else if (object->pointer + object->size <= ptr)
420 rb = object->rb_node.rb_right;
421 else if (object->pointer == ptr || alias)
424 kmemleak_warn("Found object by alias at 0x%08lx\n",
426 dump_object_info(object);
434 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
435 * that once an object's use_count reached 0, the RCU freeing was already
436 * registered and the object should no longer be used. This function must be
437 * called under the protection of rcu_read_lock().
439 static int get_object(struct kmemleak_object *object)
441 return atomic_inc_not_zero(&object->use_count);
445 * RCU callback to free a kmemleak_object.
447 static void free_object_rcu(struct rcu_head *rcu)
449 struct hlist_node *tmp;
450 struct kmemleak_scan_area *area;
451 struct kmemleak_object *object =
452 container_of(rcu, struct kmemleak_object, rcu);
455 * Once use_count is 0 (guaranteed by put_object), there is no other
456 * code accessing this object, hence no need for locking.
458 hlist_for_each_entry_safe(area, tmp, &object->area_list, node) {
459 hlist_del(&area->node);
460 kmem_cache_free(scan_area_cache, area);
462 kmem_cache_free(object_cache, object);
466 * Decrement the object use_count. Once the count is 0, free the object using
467 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
468 * delete_object() path, the delayed RCU freeing ensures that there is no
469 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
472 static void put_object(struct kmemleak_object *object)
474 if (!atomic_dec_and_test(&object->use_count))
477 /* should only get here after delete_object was called */
478 WARN_ON(object->flags & OBJECT_ALLOCATED);
480 call_rcu(&object->rcu, free_object_rcu);
484 * Look up an object in the object search tree and increase its use_count.
486 static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
489 struct kmemleak_object *object = NULL;
492 read_lock_irqsave(&kmemleak_lock, flags);
493 if (ptr >= min_addr && ptr < max_addr)
494 object = lookup_object(ptr, alias);
495 read_unlock_irqrestore(&kmemleak_lock, flags);
497 /* check whether the object is still available */
498 if (object && !get_object(object))
506 * Look up an object in the object search tree and remove it from both
507 * object_tree_root and object_list. The returned object's use_count should be
508 * at least 1, as initially set by create_object().
510 static struct kmemleak_object *find_and_remove_object(unsigned long ptr, int alias)
513 struct kmemleak_object *object;
515 write_lock_irqsave(&kmemleak_lock, flags);
516 object = lookup_object(ptr, alias);
518 rb_erase(&object->rb_node, &object_tree_root);
519 list_del_rcu(&object->object_list);
521 write_unlock_irqrestore(&kmemleak_lock, flags);
527 * Save stack trace to the given array of MAX_TRACE size.
529 static int __save_stack_trace(unsigned long *trace)
531 struct stack_trace stack_trace;
533 stack_trace.max_entries = MAX_TRACE;
534 stack_trace.nr_entries = 0;
535 stack_trace.entries = trace;
536 stack_trace.skip = 2;
537 save_stack_trace(&stack_trace);
539 return stack_trace.nr_entries;
543 * Create the metadata (struct kmemleak_object) corresponding to an allocated
544 * memory block and add it to the object_list and object_tree_root.
546 static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
547 int min_count, gfp_t gfp)
550 struct kmemleak_object *object, *parent;
551 struct rb_node **link, *rb_parent;
553 object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
555 pr_warning("Cannot allocate a kmemleak_object structure\n");
560 INIT_LIST_HEAD(&object->object_list);
561 INIT_LIST_HEAD(&object->gray_list);
562 INIT_HLIST_HEAD(&object->area_list);
563 spin_lock_init(&object->lock);
564 atomic_set(&object->use_count, 1);
565 object->flags = OBJECT_ALLOCATED;
566 object->pointer = ptr;
568 object->min_count = min_count;
569 object->count = 0; /* white color initially */
570 object->jiffies = jiffies;
571 object->checksum = 0;
573 /* task information */
576 strncpy(object->comm, "hardirq", sizeof(object->comm));
577 } else if (in_softirq()) {
579 strncpy(object->comm, "softirq", sizeof(object->comm));
581 object->pid = current->pid;
583 * There is a small chance of a race with set_task_comm(),
584 * however using get_task_comm() here may cause locking
585 * dependency issues with current->alloc_lock. In the worst
586 * case, the command line is not correct.
588 strncpy(object->comm, current->comm, sizeof(object->comm));
591 /* kernel backtrace */
592 object->trace_len = __save_stack_trace(object->trace);
594 write_lock_irqsave(&kmemleak_lock, flags);
596 min_addr = min(min_addr, ptr);
597 max_addr = max(max_addr, ptr + size);
598 link = &object_tree_root.rb_node;
602 parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
603 if (ptr + size <= parent->pointer)
604 link = &parent->rb_node.rb_left;
605 else if (parent->pointer + parent->size <= ptr)
606 link = &parent->rb_node.rb_right;
608 kmemleak_stop("Cannot insert 0x%lx into the object "
609 "search tree (overlaps existing)\n",
612 * No need for parent->lock here since "parent" cannot
613 * be freed while the kmemleak_lock is held.
615 dump_object_info(parent);
616 kmem_cache_free(object_cache, object);
621 rb_link_node(&object->rb_node, rb_parent, link);
622 rb_insert_color(&object->rb_node, &object_tree_root);
624 list_add_tail_rcu(&object->object_list, &object_list);
626 write_unlock_irqrestore(&kmemleak_lock, flags);
631 * Mark the object as not allocated and schedule RCU freeing via put_object().
633 static void __delete_object(struct kmemleak_object *object)
637 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
638 WARN_ON(atomic_read(&object->use_count) < 1);
641 * Locking here also ensures that the corresponding memory block
642 * cannot be freed when it is being scanned.
644 spin_lock_irqsave(&object->lock, flags);
645 object->flags &= ~OBJECT_ALLOCATED;
646 spin_unlock_irqrestore(&object->lock, flags);
651 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
654 static void delete_object_full(unsigned long ptr)
656 struct kmemleak_object *object;
658 object = find_and_remove_object(ptr, 0);
661 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
666 __delete_object(object);
670 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
671 * delete it. If the memory block is partially freed, the function may create
672 * additional metadata for the remaining parts of the block.
674 static void delete_object_part(unsigned long ptr, size_t size)
676 struct kmemleak_object *object;
677 unsigned long start, end;
679 object = find_and_remove_object(ptr, 1);
682 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
683 "(size %zu)\n", ptr, size);
689 * Create one or two objects that may result from the memory block
690 * split. Note that partial freeing is only done by free_bootmem() and
691 * this happens before kmemleak_init() is called. The path below is
692 * only executed during early log recording in kmemleak_init(), so
693 * GFP_KERNEL is enough.
695 start = object->pointer;
696 end = object->pointer + object->size;
698 create_object(start, ptr - start, object->min_count,
700 if (ptr + size < end)
701 create_object(ptr + size, end - ptr - size, object->min_count,
704 __delete_object(object);
707 static void __paint_it(struct kmemleak_object *object, int color)
709 object->min_count = color;
710 if (color == KMEMLEAK_BLACK)
711 object->flags |= OBJECT_NO_SCAN;
714 static void paint_it(struct kmemleak_object *object, int color)
718 spin_lock_irqsave(&object->lock, flags);
719 __paint_it(object, color);
720 spin_unlock_irqrestore(&object->lock, flags);
723 static void paint_ptr(unsigned long ptr, int color)
725 struct kmemleak_object *object;
727 object = find_and_get_object(ptr, 0);
729 kmemleak_warn("Trying to color unknown object "
730 "at 0x%08lx as %s\n", ptr,
731 (color == KMEMLEAK_GREY) ? "Grey" :
732 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
735 paint_it(object, color);
740 * Mark an object permanently as gray-colored so that it can no longer be
741 * reported as a leak. This is used in general to mark a false positive.
743 static void make_gray_object(unsigned long ptr)
745 paint_ptr(ptr, KMEMLEAK_GREY);
749 * Mark the object as black-colored so that it is ignored from scans and
752 static void make_black_object(unsigned long ptr)
754 paint_ptr(ptr, KMEMLEAK_BLACK);
758 * Add a scanning area to the object. If at least one such area is added,
759 * kmemleak will only scan these ranges rather than the whole memory block.
761 static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
764 struct kmemleak_object *object;
765 struct kmemleak_scan_area *area;
767 object = find_and_get_object(ptr, 1);
769 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
774 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
776 pr_warning("Cannot allocate a scan area\n");
780 spin_lock_irqsave(&object->lock, flags);
781 if (size == SIZE_MAX) {
782 size = object->pointer + object->size - ptr;
783 } else if (ptr + size > object->pointer + object->size) {
784 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
785 dump_object_info(object);
786 kmem_cache_free(scan_area_cache, area);
790 INIT_HLIST_NODE(&area->node);
794 hlist_add_head(&area->node, &object->area_list);
796 spin_unlock_irqrestore(&object->lock, flags);
802 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
803 * pointer. Such object will not be scanned by kmemleak but references to it
806 static void object_no_scan(unsigned long ptr)
809 struct kmemleak_object *object;
811 object = find_and_get_object(ptr, 0);
813 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
817 spin_lock_irqsave(&object->lock, flags);
818 object->flags |= OBJECT_NO_SCAN;
819 spin_unlock_irqrestore(&object->lock, flags);
824 * Log an early kmemleak_* call to the early_log buffer. These calls will be
825 * processed later once kmemleak is fully initialized.
827 static void __init log_early(int op_type, const void *ptr, size_t size,
831 struct early_log *log;
833 if (kmemleak_error) {
834 /* kmemleak stopped recording, just count the requests */
839 if (crt_early_log >= ARRAY_SIZE(early_log)) {
845 * There is no need for locking since the kernel is still in UP mode
846 * at this stage. Disabling the IRQs is enough.
848 local_irq_save(flags);
849 log = &early_log[crt_early_log];
850 log->op_type = op_type;
853 log->min_count = min_count;
854 log->trace_len = __save_stack_trace(log->trace);
856 local_irq_restore(flags);
860 * Log an early allocated block and populate the stack trace.
862 static void early_alloc(struct early_log *log)
864 struct kmemleak_object *object;
868 if (!kmemleak_enabled || !log->ptr || IS_ERR(log->ptr))
872 * RCU locking needed to ensure object is not freed via put_object().
875 object = create_object((unsigned long)log->ptr, log->size,
876 log->min_count, GFP_ATOMIC);
879 spin_lock_irqsave(&object->lock, flags);
880 for (i = 0; i < log->trace_len; i++)
881 object->trace[i] = log->trace[i];
882 object->trace_len = log->trace_len;
883 spin_unlock_irqrestore(&object->lock, flags);
889 * Log an early allocated block and populate the stack trace.
891 static void early_alloc_percpu(struct early_log *log)
894 const void __percpu *ptr = log->ptr;
896 for_each_possible_cpu(cpu) {
897 log->ptr = per_cpu_ptr(ptr, cpu);
903 * kmemleak_alloc - register a newly allocated object
904 * @ptr: pointer to beginning of the object
905 * @size: size of the object
906 * @min_count: minimum number of references to this object. If during memory
907 * scanning a number of references less than @min_count is found,
908 * the object is reported as a memory leak. If @min_count is 0,
909 * the object is never reported as a leak. If @min_count is -1,
910 * the object is ignored (not scanned and not reported as a leak)
911 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
913 * This function is called from the kernel allocators when a new object
914 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
916 void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
919 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
921 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
922 create_object((unsigned long)ptr, size, min_count, gfp);
923 else if (kmemleak_early_log)
924 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
926 EXPORT_SYMBOL_GPL(kmemleak_alloc);
929 * kmemleak_alloc_percpu - register a newly allocated __percpu object
930 * @ptr: __percpu pointer to beginning of the object
931 * @size: size of the object
933 * This function is called from the kernel percpu allocator when a new object
934 * (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL
937 void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size)
941 pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
944 * Percpu allocations are only scanned and not reported as leaks
945 * (min_count is set to 0).
947 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
948 for_each_possible_cpu(cpu)
949 create_object((unsigned long)per_cpu_ptr(ptr, cpu),
950 size, 0, GFP_KERNEL);
951 else if (kmemleak_early_log)
952 log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
954 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
957 * kmemleak_free - unregister a previously registered object
958 * @ptr: pointer to beginning of the object
960 * This function is called from the kernel allocators when an object (memory
961 * block) is freed (kmem_cache_free, kfree, vfree etc.).
963 void __ref kmemleak_free(const void *ptr)
965 pr_debug("%s(0x%p)\n", __func__, ptr);
967 if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
968 delete_object_full((unsigned long)ptr);
969 else if (kmemleak_early_log)
970 log_early(KMEMLEAK_FREE, ptr, 0, 0);
972 EXPORT_SYMBOL_GPL(kmemleak_free);
975 * kmemleak_free_part - partially unregister a previously registered object
976 * @ptr: pointer to the beginning or inside the object. This also
977 * represents the start of the range to be freed
978 * @size: size to be unregistered
980 * This function is called when only a part of a memory block is freed
981 * (usually from the bootmem allocator).
983 void __ref kmemleak_free_part(const void *ptr, size_t size)
985 pr_debug("%s(0x%p)\n", __func__, ptr);
987 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
988 delete_object_part((unsigned long)ptr, size);
989 else if (kmemleak_early_log)
990 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
992 EXPORT_SYMBOL_GPL(kmemleak_free_part);
995 * kmemleak_free_percpu - unregister a previously registered __percpu object
996 * @ptr: __percpu pointer to beginning of the object
998 * This function is called from the kernel percpu allocator when an object
999 * (memory block) is freed (free_percpu).
1001 void __ref kmemleak_free_percpu(const void __percpu *ptr)
1005 pr_debug("%s(0x%p)\n", __func__, ptr);
1007 if (kmemleak_free_enabled && ptr && !IS_ERR(ptr))
1008 for_each_possible_cpu(cpu)
1009 delete_object_full((unsigned long)per_cpu_ptr(ptr,
1011 else if (kmemleak_early_log)
1012 log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
1014 EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
1017 * kmemleak_update_trace - update object allocation stack trace
1018 * @ptr: pointer to beginning of the object
1020 * Override the object allocation stack trace for cases where the actual
1021 * allocation place is not always useful.
1023 void __ref kmemleak_update_trace(const void *ptr)
1025 struct kmemleak_object *object;
1026 unsigned long flags;
1028 pr_debug("%s(0x%p)\n", __func__, ptr);
1030 if (!kmemleak_enabled || IS_ERR_OR_NULL(ptr))
1033 object = find_and_get_object((unsigned long)ptr, 1);
1036 kmemleak_warn("Updating stack trace for unknown object at %p\n",
1042 spin_lock_irqsave(&object->lock, flags);
1043 object->trace_len = __save_stack_trace(object->trace);
1044 spin_unlock_irqrestore(&object->lock, flags);
1048 EXPORT_SYMBOL(kmemleak_update_trace);
1051 * kmemleak_not_leak - mark an allocated object as false positive
1052 * @ptr: pointer to beginning of the object
1054 * Calling this function on an object will cause the memory block to no longer
1055 * be reported as leak and always be scanned.
1057 void __ref kmemleak_not_leak(const void *ptr)
1059 pr_debug("%s(0x%p)\n", __func__, ptr);
1061 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1062 make_gray_object((unsigned long)ptr);
1063 else if (kmemleak_early_log)
1064 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
1066 EXPORT_SYMBOL(kmemleak_not_leak);
1069 * kmemleak_ignore - ignore an allocated object
1070 * @ptr: pointer to beginning of the object
1072 * Calling this function on an object will cause the memory block to be
1073 * ignored (not scanned and not reported as a leak). This is usually done when
1074 * it is known that the corresponding block is not a leak and does not contain
1075 * any references to other allocated memory blocks.
1077 void __ref kmemleak_ignore(const void *ptr)
1079 pr_debug("%s(0x%p)\n", __func__, ptr);
1081 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1082 make_black_object((unsigned long)ptr);
1083 else if (kmemleak_early_log)
1084 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
1086 EXPORT_SYMBOL(kmemleak_ignore);
1089 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1090 * @ptr: pointer to beginning or inside the object. This also
1091 * represents the start of the scan area
1092 * @size: size of the scan area
1093 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1095 * This function is used when it is known that only certain parts of an object
1096 * contain references to other objects. Kmemleak will only scan these areas
1097 * reducing the number false negatives.
1099 void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
1101 pr_debug("%s(0x%p)\n", __func__, ptr);
1103 if (kmemleak_enabled && ptr && size && !IS_ERR(ptr))
1104 add_scan_area((unsigned long)ptr, size, gfp);
1105 else if (kmemleak_early_log)
1106 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
1108 EXPORT_SYMBOL(kmemleak_scan_area);
1111 * kmemleak_no_scan - do not scan an allocated object
1112 * @ptr: pointer to beginning of the object
1114 * This function notifies kmemleak not to scan the given memory block. Useful
1115 * in situations where it is known that the given object does not contain any
1116 * references to other objects. Kmemleak will not scan such objects reducing
1117 * the number of false negatives.
1119 void __ref kmemleak_no_scan(const void *ptr)
1121 pr_debug("%s(0x%p)\n", __func__, ptr);
1123 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1124 object_no_scan((unsigned long)ptr);
1125 else if (kmemleak_early_log)
1126 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
1128 EXPORT_SYMBOL(kmemleak_no_scan);
1131 * Update an object's checksum and return true if it was modified.
1133 static bool update_checksum(struct kmemleak_object *object)
1135 u32 old_csum = object->checksum;
1137 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
1140 kasan_disable_current();
1141 object->checksum = crc32(0, (void *)object->pointer, object->size);
1142 kasan_enable_current();
1144 return object->checksum != old_csum;
1148 * Memory scanning is a long process and it needs to be interruptable. This
1149 * function checks whether such interrupt condition occurred.
1151 static int scan_should_stop(void)
1153 if (!kmemleak_enabled)
1157 * This function may be called from either process or kthread context,
1158 * hence the need to check for both stop conditions.
1161 return signal_pending(current);
1163 return kthread_should_stop();
1169 * Scan a memory block (exclusive range) for valid pointers and add those
1170 * found to the gray list.
1172 static void scan_block(void *_start, void *_end,
1173 struct kmemleak_object *scanned, int allow_resched)
1176 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1177 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1179 for (ptr = start; ptr < end; ptr++) {
1180 struct kmemleak_object *object;
1181 unsigned long flags;
1182 unsigned long pointer;
1186 if (scan_should_stop())
1189 /* don't scan uninitialized memory */
1190 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1194 kasan_disable_current();
1196 kasan_enable_current();
1198 object = find_and_get_object(pointer, 1);
1201 if (object == scanned) {
1202 /* self referenced, ignore */
1208 * Avoid the lockdep recursive warning on object->lock being
1209 * previously acquired in scan_object(). These locks are
1210 * enclosed by scan_mutex.
1212 spin_lock_irqsave_nested(&object->lock, flags,
1213 SINGLE_DEPTH_NESTING);
1214 if (!color_white(object)) {
1215 /* non-orphan, ignored or new */
1216 spin_unlock_irqrestore(&object->lock, flags);
1222 * Increase the object's reference count (number of pointers
1223 * to the memory block). If this count reaches the required
1224 * minimum, the object's color will become gray and it will be
1225 * added to the gray_list.
1228 if (color_gray(object)) {
1229 list_add_tail(&object->gray_list, &gray_list);
1230 spin_unlock_irqrestore(&object->lock, flags);
1234 spin_unlock_irqrestore(&object->lock, flags);
1240 * Scan a memory block corresponding to a kmemleak_object. A condition is
1241 * that object->use_count >= 1.
1243 static void scan_object(struct kmemleak_object *object)
1245 struct kmemleak_scan_area *area;
1246 unsigned long flags;
1249 * Once the object->lock is acquired, the corresponding memory block
1250 * cannot be freed (the same lock is acquired in delete_object).
1252 spin_lock_irqsave(&object->lock, flags);
1253 if (object->flags & OBJECT_NO_SCAN)
1255 if (!(object->flags & OBJECT_ALLOCATED))
1256 /* already freed object */
1258 if (hlist_empty(&object->area_list)) {
1259 void *start = (void *)object->pointer;
1260 void *end = (void *)(object->pointer + object->size);
1262 while (start < end && (object->flags & OBJECT_ALLOCATED) &&
1263 !(object->flags & OBJECT_NO_SCAN)) {
1264 scan_block(start, min(start + MAX_SCAN_SIZE, end),
1266 start += MAX_SCAN_SIZE;
1268 spin_unlock_irqrestore(&object->lock, flags);
1270 spin_lock_irqsave(&object->lock, flags);
1273 hlist_for_each_entry(area, &object->area_list, node)
1274 scan_block((void *)area->start,
1275 (void *)(area->start + area->size),
1278 spin_unlock_irqrestore(&object->lock, flags);
1282 * Scan the objects already referenced (gray objects). More objects will be
1283 * referenced and, if there are no memory leaks, all the objects are scanned.
1285 static void scan_gray_list(void)
1287 struct kmemleak_object *object, *tmp;
1290 * The list traversal is safe for both tail additions and removals
1291 * from inside the loop. The kmemleak objects cannot be freed from
1292 * outside the loop because their use_count was incremented.
1294 object = list_entry(gray_list.next, typeof(*object), gray_list);
1295 while (&object->gray_list != &gray_list) {
1298 /* may add new objects to the list */
1299 if (!scan_should_stop())
1300 scan_object(object);
1302 tmp = list_entry(object->gray_list.next, typeof(*object),
1305 /* remove the object from the list and release it */
1306 list_del(&object->gray_list);
1311 WARN_ON(!list_empty(&gray_list));
1315 * Scan data sections and all the referenced memory blocks allocated via the
1316 * kernel's standard allocators. This function must be called with the
1319 static void kmemleak_scan(void)
1321 unsigned long flags;
1322 struct kmemleak_object *object;
1326 jiffies_last_scan = jiffies;
1328 /* prepare the kmemleak_object's */
1330 list_for_each_entry_rcu(object, &object_list, object_list) {
1331 spin_lock_irqsave(&object->lock, flags);
1334 * With a few exceptions there should be a maximum of
1335 * 1 reference to any object at this point.
1337 if (atomic_read(&object->use_count) > 1) {
1338 pr_debug("object->use_count = %d\n",
1339 atomic_read(&object->use_count));
1340 dump_object_info(object);
1343 /* reset the reference count (whiten the object) */
1345 if (color_gray(object) && get_object(object))
1346 list_add_tail(&object->gray_list, &gray_list);
1348 spin_unlock_irqrestore(&object->lock, flags);
1352 /* data/bss scanning */
1353 scan_block(_sdata, _edata, NULL, 1);
1354 scan_block(__bss_start, __bss_stop, NULL, 1);
1357 /* per-cpu sections scanning */
1358 for_each_possible_cpu(i)
1359 scan_block(__per_cpu_start + per_cpu_offset(i),
1360 __per_cpu_end + per_cpu_offset(i), NULL, 1);
1364 * Struct page scanning for each node.
1367 for_each_online_node(i) {
1368 unsigned long start_pfn = node_start_pfn(i);
1369 unsigned long end_pfn = node_end_pfn(i);
1372 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1375 if (!pfn_valid(pfn))
1377 page = pfn_to_page(pfn);
1378 /* only scan if page is in use */
1379 if (page_count(page) == 0)
1381 scan_block(page, page + 1, NULL, 1);
1387 * Scanning the task stacks (may introduce false negatives).
1389 if (kmemleak_stack_scan) {
1390 struct task_struct *p, *g;
1392 read_lock(&tasklist_lock);
1393 do_each_thread(g, p) {
1394 scan_block(task_stack_page(p), task_stack_page(p) +
1395 THREAD_SIZE, NULL, 0);
1396 } while_each_thread(g, p);
1397 read_unlock(&tasklist_lock);
1401 * Scan the objects already referenced from the sections scanned
1407 * Check for new or unreferenced objects modified since the previous
1408 * scan and color them gray until the next scan.
1411 list_for_each_entry_rcu(object, &object_list, object_list) {
1412 spin_lock_irqsave(&object->lock, flags);
1413 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1414 && update_checksum(object) && get_object(object)) {
1415 /* color it gray temporarily */
1416 object->count = object->min_count;
1417 list_add_tail(&object->gray_list, &gray_list);
1419 spin_unlock_irqrestore(&object->lock, flags);
1424 * Re-scan the gray list for modified unreferenced objects.
1429 * If scanning was stopped do not report any new unreferenced objects.
1431 if (scan_should_stop())
1435 * Scanning result reporting.
1438 list_for_each_entry_rcu(object, &object_list, object_list) {
1439 spin_lock_irqsave(&object->lock, flags);
1440 if (unreferenced_object(object) &&
1441 !(object->flags & OBJECT_REPORTED)) {
1442 object->flags |= OBJECT_REPORTED;
1445 spin_unlock_irqrestore(&object->lock, flags);
1450 kmemleak_found_leaks = true;
1452 pr_info("%d new suspected memory leaks (see "
1453 "/sys/kernel/debug/kmemleak)\n", new_leaks);
1459 * Thread function performing automatic memory scanning. Unreferenced objects
1460 * at the end of a memory scan are reported but only the first time.
1462 static int kmemleak_scan_thread(void *arg)
1464 static int first_run = 1;
1466 pr_info("Automatic memory scanning thread started\n");
1467 set_user_nice(current, 10);
1470 * Wait before the first scan to allow the system to fully initialize.
1474 ssleep(SECS_FIRST_SCAN);
1477 while (!kthread_should_stop()) {
1478 signed long timeout = jiffies_scan_wait;
1480 mutex_lock(&scan_mutex);
1482 mutex_unlock(&scan_mutex);
1484 /* wait before the next scan */
1485 while (timeout && !kthread_should_stop())
1486 timeout = schedule_timeout_interruptible(timeout);
1489 pr_info("Automatic memory scanning thread ended\n");
1495 * Start the automatic memory scanning thread. This function must be called
1496 * with the scan_mutex held.
1498 static void start_scan_thread(void)
1502 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1503 if (IS_ERR(scan_thread)) {
1504 pr_warning("Failed to create the scan thread\n");
1510 * Stop the automatic memory scanning thread. This function must be called
1511 * with the scan_mutex held.
1513 static void stop_scan_thread(void)
1516 kthread_stop(scan_thread);
1522 * Iterate over the object_list and return the first valid object at or after
1523 * the required position with its use_count incremented. The function triggers
1524 * a memory scanning when the pos argument points to the first position.
1526 static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1528 struct kmemleak_object *object;
1532 err = mutex_lock_interruptible(&scan_mutex);
1534 return ERR_PTR(err);
1537 list_for_each_entry_rcu(object, &object_list, object_list) {
1540 if (get_object(object))
1549 * Return the next object in the object_list. The function decrements the
1550 * use_count of the previous object and increases that of the next one.
1552 static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1554 struct kmemleak_object *prev_obj = v;
1555 struct kmemleak_object *next_obj = NULL;
1556 struct kmemleak_object *obj = prev_obj;
1560 list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
1561 if (get_object(obj)) {
1567 put_object(prev_obj);
1572 * Decrement the use_count of the last object required, if any.
1574 static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1578 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1579 * waiting was interrupted, so only release it if !IS_ERR.
1582 mutex_unlock(&scan_mutex);
1589 * Print the information for an unreferenced object to the seq file.
1591 static int kmemleak_seq_show(struct seq_file *seq, void *v)
1593 struct kmemleak_object *object = v;
1594 unsigned long flags;
1596 spin_lock_irqsave(&object->lock, flags);
1597 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
1598 print_unreferenced(seq, object);
1599 spin_unlock_irqrestore(&object->lock, flags);
1603 static const struct seq_operations kmemleak_seq_ops = {
1604 .start = kmemleak_seq_start,
1605 .next = kmemleak_seq_next,
1606 .stop = kmemleak_seq_stop,
1607 .show = kmemleak_seq_show,
1610 static int kmemleak_open(struct inode *inode, struct file *file)
1612 return seq_open(file, &kmemleak_seq_ops);
1615 static int dump_str_object_info(const char *str)
1617 unsigned long flags;
1618 struct kmemleak_object *object;
1621 if (kstrtoul(str, 0, &addr))
1623 object = find_and_get_object(addr, 0);
1625 pr_info("Unknown object at 0x%08lx\n", addr);
1629 spin_lock_irqsave(&object->lock, flags);
1630 dump_object_info(object);
1631 spin_unlock_irqrestore(&object->lock, flags);
1638 * We use grey instead of black to ensure we can do future scans on the same
1639 * objects. If we did not do future scans these black objects could
1640 * potentially contain references to newly allocated objects in the future and
1641 * we'd end up with false positives.
1643 static void kmemleak_clear(void)
1645 struct kmemleak_object *object;
1646 unsigned long flags;
1649 list_for_each_entry_rcu(object, &object_list, object_list) {
1650 spin_lock_irqsave(&object->lock, flags);
1651 if ((object->flags & OBJECT_REPORTED) &&
1652 unreferenced_object(object))
1653 __paint_it(object, KMEMLEAK_GREY);
1654 spin_unlock_irqrestore(&object->lock, flags);
1658 kmemleak_found_leaks = false;
1661 static void __kmemleak_do_cleanup(void);
1664 * File write operation to configure kmemleak at run-time. The following
1665 * commands can be written to the /sys/kernel/debug/kmemleak file:
1666 * off - disable kmemleak (irreversible)
1667 * stack=on - enable the task stacks scanning
1668 * stack=off - disable the tasks stacks scanning
1669 * scan=on - start the automatic memory scanning thread
1670 * scan=off - stop the automatic memory scanning thread
1671 * scan=... - set the automatic memory scanning period in seconds (0 to
1673 * scan - trigger a memory scan
1674 * clear - mark all current reported unreferenced kmemleak objects as
1675 * grey to ignore printing them, or free all kmemleak objects
1676 * if kmemleak has been disabled.
1677 * dump=... - dump information about the object found at the given address
1679 static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1680 size_t size, loff_t *ppos)
1686 buf_size = min(size, (sizeof(buf) - 1));
1687 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1691 ret = mutex_lock_interruptible(&scan_mutex);
1695 if (strncmp(buf, "clear", 5) == 0) {
1696 if (kmemleak_enabled)
1699 __kmemleak_do_cleanup();
1703 if (!kmemleak_enabled) {
1708 if (strncmp(buf, "off", 3) == 0)
1710 else if (strncmp(buf, "stack=on", 8) == 0)
1711 kmemleak_stack_scan = 1;
1712 else if (strncmp(buf, "stack=off", 9) == 0)
1713 kmemleak_stack_scan = 0;
1714 else if (strncmp(buf, "scan=on", 7) == 0)
1715 start_scan_thread();
1716 else if (strncmp(buf, "scan=off", 8) == 0)
1718 else if (strncmp(buf, "scan=", 5) == 0) {
1721 ret = kstrtoul(buf + 5, 0, &secs);
1726 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1727 start_scan_thread();
1729 } else if (strncmp(buf, "scan", 4) == 0)
1731 else if (strncmp(buf, "dump=", 5) == 0)
1732 ret = dump_str_object_info(buf + 5);
1737 mutex_unlock(&scan_mutex);
1741 /* ignore the rest of the buffer, only one command at a time */
1746 static const struct file_operations kmemleak_fops = {
1747 .owner = THIS_MODULE,
1748 .open = kmemleak_open,
1750 .write = kmemleak_write,
1751 .llseek = seq_lseek,
1752 .release = seq_release,
1755 static void __kmemleak_do_cleanup(void)
1757 struct kmemleak_object *object;
1760 list_for_each_entry_rcu(object, &object_list, object_list)
1761 delete_object_full(object->pointer);
1766 * Stop the memory scanning thread and free the kmemleak internal objects if
1767 * no previous scan thread (otherwise, kmemleak may still have some useful
1768 * information on memory leaks).
1770 static void kmemleak_do_cleanup(struct work_struct *work)
1775 * Once the scan thread has stopped, it is safe to no longer track
1776 * object freeing. Ordering of the scan thread stopping and the memory
1777 * accesses below is guaranteed by the kthread_stop() function.
1779 kmemleak_free_enabled = 0;
1781 if (!kmemleak_found_leaks)
1782 __kmemleak_do_cleanup();
1784 pr_info("Kmemleak disabled without freeing internal data. "
1785 "Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\"\n");
1788 static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
1791 * Disable kmemleak. No memory allocation/freeing will be traced once this
1792 * function is called. Disabling kmemleak is an irreversible operation.
1794 static void kmemleak_disable(void)
1796 /* atomically check whether it was already invoked */
1797 if (cmpxchg(&kmemleak_error, 0, 1))
1800 /* stop any memory operation tracing */
1801 kmemleak_enabled = 0;
1803 /* check whether it is too early for a kernel thread */
1804 if (kmemleak_initialized)
1805 schedule_work(&cleanup_work);
1807 kmemleak_free_enabled = 0;
1809 pr_info("Kernel memory leak detector disabled\n");
1813 * Allow boot-time kmemleak disabling (enabled by default).
1815 static int kmemleak_boot_config(char *str)
1819 if (strcmp(str, "off") == 0)
1821 else if (strcmp(str, "on") == 0)
1822 kmemleak_skip_disable = 1;
1827 early_param("kmemleak", kmemleak_boot_config);
1829 static void __init print_log_trace(struct early_log *log)
1831 struct stack_trace trace;
1833 trace.nr_entries = log->trace_len;
1834 trace.entries = log->trace;
1836 pr_notice("Early log backtrace:\n");
1837 print_stack_trace(&trace, 2);
1841 * Kmemleak initialization.
1843 void __init kmemleak_init(void)
1846 unsigned long flags;
1848 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1849 if (!kmemleak_skip_disable) {
1850 kmemleak_early_log = 0;
1856 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1857 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1859 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1860 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1862 if (crt_early_log >= ARRAY_SIZE(early_log))
1863 pr_warning("Early log buffer exceeded (%d), please increase "
1864 "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log);
1866 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1867 local_irq_save(flags);
1868 kmemleak_early_log = 0;
1869 if (kmemleak_error) {
1870 local_irq_restore(flags);
1873 kmemleak_enabled = 1;
1874 kmemleak_free_enabled = 1;
1876 local_irq_restore(flags);
1879 * This is the point where tracking allocations is safe. Automatic
1880 * scanning is started during the late initcall. Add the early logged
1881 * callbacks to the kmemleak infrastructure.
1883 for (i = 0; i < crt_early_log; i++) {
1884 struct early_log *log = &early_log[i];
1886 switch (log->op_type) {
1887 case KMEMLEAK_ALLOC:
1890 case KMEMLEAK_ALLOC_PERCPU:
1891 early_alloc_percpu(log);
1894 kmemleak_free(log->ptr);
1896 case KMEMLEAK_FREE_PART:
1897 kmemleak_free_part(log->ptr, log->size);
1899 case KMEMLEAK_FREE_PERCPU:
1900 kmemleak_free_percpu(log->ptr);
1902 case KMEMLEAK_NOT_LEAK:
1903 kmemleak_not_leak(log->ptr);
1905 case KMEMLEAK_IGNORE:
1906 kmemleak_ignore(log->ptr);
1908 case KMEMLEAK_SCAN_AREA:
1909 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
1911 case KMEMLEAK_NO_SCAN:
1912 kmemleak_no_scan(log->ptr);
1915 kmemleak_warn("Unknown early log operation: %d\n",
1919 if (kmemleak_warning) {
1920 print_log_trace(log);
1921 kmemleak_warning = 0;
1927 * Late initialization function.
1929 static int __init kmemleak_late_init(void)
1931 struct dentry *dentry;
1933 kmemleak_initialized = 1;
1935 if (kmemleak_error) {
1937 * Some error occurred and kmemleak was disabled. There is a
1938 * small chance that kmemleak_disable() was called immediately
1939 * after setting kmemleak_initialized and we may end up with
1940 * two clean-up threads but serialized by scan_mutex.
1942 schedule_work(&cleanup_work);
1946 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1949 pr_warning("Failed to create the debugfs kmemleak file\n");
1950 mutex_lock(&scan_mutex);
1951 start_scan_thread();
1952 mutex_unlock(&scan_mutex);
1954 pr_info("Kernel memory leak detector initialized\n");
1958 late_initcall(kmemleak_late_init);