fs: prevent doing FALLOC_FL_ZERO_RANGE on append only file
[linux/fpc-iii.git] / mm / kmemleak.c
blob91d67eaee0500796c9e5569fedc7cc5775002dda
1 /*
2 * mm/kmemleak.c
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.
24 * Notes on locking
25 * ----------------
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
54 * pointer
56 * The kmemleak_object structures have a use_count incremented or decremented
57 * using the get_object()/put_object() functions. When the use_count becomes
58 * 0, this count can no longer be incremented and put_object() schedules the
59 * kmemleak_object freeing via an RCU callback. All calls to the get_object()
60 * function must be protected by rcu_read_lock() to avoid accessing a freed
61 * structure.
64 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
66 #include <linux/init.h>
67 #include <linux/kernel.h>
68 #include <linux/list.h>
69 #include <linux/sched.h>
70 #include <linux/jiffies.h>
71 #include <linux/delay.h>
72 #include <linux/export.h>
73 #include <linux/kthread.h>
74 #include <linux/rbtree.h>
75 #include <linux/fs.h>
76 #include <linux/debugfs.h>
77 #include <linux/seq_file.h>
78 #include <linux/cpumask.h>
79 #include <linux/spinlock.h>
80 #include <linux/mutex.h>
81 #include <linux/rcupdate.h>
82 #include <linux/stacktrace.h>
83 #include <linux/cache.h>
84 #include <linux/percpu.h>
85 #include <linux/hardirq.h>
86 #include <linux/mmzone.h>
87 #include <linux/slab.h>
88 #include <linux/thread_info.h>
89 #include <linux/err.h>
90 #include <linux/uaccess.h>
91 #include <linux/string.h>
92 #include <linux/nodemask.h>
93 #include <linux/mm.h>
94 #include <linux/workqueue.h>
95 #include <linux/crc32.h>
97 #include <asm/sections.h>
98 #include <asm/processor.h>
99 #include <linux/atomic.h>
101 #include <linux/kmemcheck.h>
102 #include <linux/kmemleak.h>
103 #include <linux/memory_hotplug.h>
106 * Kmemleak configuration and common defines.
108 #define MAX_TRACE 16 /* stack trace length */
109 #define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
110 #define SECS_FIRST_SCAN 60 /* delay before the first scan */
111 #define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
112 #define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
114 #define BYTES_PER_POINTER sizeof(void *)
116 /* GFP bitmask for kmemleak internal allocations */
117 #define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
118 __GFP_NORETRY | __GFP_NOMEMALLOC | \
119 __GFP_NOWARN)
121 /* scanning area inside a memory block */
122 struct kmemleak_scan_area {
123 struct hlist_node node;
124 unsigned long start;
125 size_t size;
128 #define KMEMLEAK_GREY 0
129 #define KMEMLEAK_BLACK -1
132 * Structure holding the metadata for each allocated memory block.
133 * Modifications to such objects should be made while holding the
134 * object->lock. Insertions or deletions from object_list, gray_list or
135 * rb_node are already protected by the corresponding locks or mutex (see
136 * the notes on locking above). These objects are reference-counted
137 * (use_count) and freed using the RCU mechanism.
139 struct kmemleak_object {
140 spinlock_t lock;
141 unsigned long flags; /* object status flags */
142 struct list_head object_list;
143 struct list_head gray_list;
144 struct rb_node rb_node;
145 struct rcu_head rcu; /* object_list lockless traversal */
146 /* object usage count; object freed when use_count == 0 */
147 atomic_t use_count;
148 unsigned long pointer;
149 size_t size;
150 /* minimum number of a pointers found before it is considered leak */
151 int min_count;
152 /* the total number of pointers found pointing to this object */
153 int count;
154 /* checksum for detecting modified objects */
155 u32 checksum;
156 /* memory ranges to be scanned inside an object (empty for all) */
157 struct hlist_head area_list;
158 unsigned long trace[MAX_TRACE];
159 unsigned int trace_len;
160 unsigned long jiffies; /* creation timestamp */
161 pid_t pid; /* pid of the current task */
162 char comm[TASK_COMM_LEN]; /* executable name */
165 /* flag representing the memory block allocation status */
166 #define OBJECT_ALLOCATED (1 << 0)
167 /* flag set after the first reporting of an unreference object */
168 #define OBJECT_REPORTED (1 << 1)
169 /* flag set to not scan the object */
170 #define OBJECT_NO_SCAN (1 << 2)
172 /* number of bytes to print per line; must be 16 or 32 */
173 #define HEX_ROW_SIZE 16
174 /* number of bytes to print at a time (1, 2, 4, 8) */
175 #define HEX_GROUP_SIZE 1
176 /* include ASCII after the hex output */
177 #define HEX_ASCII 1
178 /* max number of lines to be printed */
179 #define HEX_MAX_LINES 2
181 /* the list of all allocated objects */
182 static LIST_HEAD(object_list);
183 /* the list of gray-colored objects (see color_gray comment below) */
184 static LIST_HEAD(gray_list);
185 /* search tree for object boundaries */
186 static struct rb_root object_tree_root = RB_ROOT;
187 /* rw_lock protecting the access to object_list and object_tree_root */
188 static DEFINE_RWLOCK(kmemleak_lock);
190 /* allocation caches for kmemleak internal data */
191 static struct kmem_cache *object_cache;
192 static struct kmem_cache *scan_area_cache;
194 /* set if tracing memory operations is enabled */
195 static int kmemleak_enabled;
196 /* set in the late_initcall if there were no errors */
197 static int kmemleak_initialized;
198 /* enables or disables early logging of the memory operations */
199 static int kmemleak_early_log = 1;
200 /* set if a kmemleak warning was issued */
201 static int kmemleak_warning;
202 /* set if a fatal kmemleak error has occurred */
203 static int kmemleak_error;
205 /* minimum and maximum address that may be valid pointers */
206 static unsigned long min_addr = ULONG_MAX;
207 static unsigned long max_addr;
209 static struct task_struct *scan_thread;
210 /* used to avoid reporting of recently allocated objects */
211 static unsigned long jiffies_min_age;
212 static unsigned long jiffies_last_scan;
213 /* delay between automatic memory scannings */
214 static signed long jiffies_scan_wait;
215 /* enables or disables the task stacks scanning */
216 static int kmemleak_stack_scan = 1;
217 /* protects the memory scanning, parameters and debug/kmemleak file access */
218 static DEFINE_MUTEX(scan_mutex);
219 /* setting kmemleak=on, will set this var, skipping the disable */
220 static int kmemleak_skip_disable;
221 /* If there are leaks that can be reported */
222 static bool kmemleak_found_leaks;
225 * Early object allocation/freeing logging. Kmemleak is initialized after the
226 * kernel allocator. However, both the kernel allocator and kmemleak may
227 * allocate memory blocks which need to be tracked. Kmemleak defines an
228 * arbitrary buffer to hold the allocation/freeing information before it is
229 * fully initialized.
232 /* kmemleak operation type for early logging */
233 enum {
234 KMEMLEAK_ALLOC,
235 KMEMLEAK_ALLOC_PERCPU,
236 KMEMLEAK_FREE,
237 KMEMLEAK_FREE_PART,
238 KMEMLEAK_FREE_PERCPU,
239 KMEMLEAK_NOT_LEAK,
240 KMEMLEAK_IGNORE,
241 KMEMLEAK_SCAN_AREA,
242 KMEMLEAK_NO_SCAN
246 * Structure holding the information passed to kmemleak callbacks during the
247 * early logging.
249 struct early_log {
250 int op_type; /* kmemleak operation type */
251 const void *ptr; /* allocated/freed memory block */
252 size_t size; /* memory block size */
253 int min_count; /* minimum reference count */
254 unsigned long trace[MAX_TRACE]; /* stack trace */
255 unsigned int trace_len; /* stack trace length */
258 /* early logging buffer and current position */
259 static struct early_log
260 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
261 static int crt_early_log __initdata;
263 static void kmemleak_disable(void);
266 * Print a warning and dump the stack trace.
268 #define kmemleak_warn(x...) do { \
269 pr_warning(x); \
270 dump_stack(); \
271 kmemleak_warning = 1; \
272 } while (0)
275 * Macro invoked when a serious kmemleak condition occurred and cannot be
276 * recovered from. Kmemleak will be disabled and further allocation/freeing
277 * tracing no longer available.
279 #define kmemleak_stop(x...) do { \
280 kmemleak_warn(x); \
281 kmemleak_disable(); \
282 } while (0)
285 * Printing of the objects hex dump to the seq file. The number of lines to be
286 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
287 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
288 * with the object->lock held.
290 static void hex_dump_object(struct seq_file *seq,
291 struct kmemleak_object *object)
293 const u8 *ptr = (const u8 *)object->pointer;
294 int i, len, remaining;
295 unsigned char linebuf[HEX_ROW_SIZE * 5];
297 /* limit the number of lines to HEX_MAX_LINES */
298 remaining = len =
299 min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
301 seq_printf(seq, " hex dump (first %d bytes):\n", len);
302 for (i = 0; i < len; i += HEX_ROW_SIZE) {
303 int linelen = min(remaining, HEX_ROW_SIZE);
305 remaining -= HEX_ROW_SIZE;
306 hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
307 HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
308 HEX_ASCII);
309 seq_printf(seq, " %s\n", linebuf);
314 * Object colors, encoded with count and min_count:
315 * - white - orphan object, not enough references to it (count < min_count)
316 * - gray - not orphan, not marked as false positive (min_count == 0) or
317 * sufficient references to it (count >= min_count)
318 * - black - ignore, it doesn't contain references (e.g. text section)
319 * (min_count == -1). No function defined for this color.
320 * Newly created objects don't have any color assigned (object->count == -1)
321 * before the next memory scan when they become white.
323 static bool color_white(const struct kmemleak_object *object)
325 return object->count != KMEMLEAK_BLACK &&
326 object->count < object->min_count;
329 static bool color_gray(const struct kmemleak_object *object)
331 return object->min_count != KMEMLEAK_BLACK &&
332 object->count >= object->min_count;
336 * Objects are considered unreferenced only if their color is white, they have
337 * not be deleted and have a minimum age to avoid false positives caused by
338 * pointers temporarily stored in CPU registers.
340 static bool unreferenced_object(struct kmemleak_object *object)
342 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
343 time_before_eq(object->jiffies + jiffies_min_age,
344 jiffies_last_scan);
348 * Printing of the unreferenced objects information to the seq file. The
349 * print_unreferenced function must be called with the object->lock held.
351 static void print_unreferenced(struct seq_file *seq,
352 struct kmemleak_object *object)
354 int i;
355 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
357 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
358 object->pointer, object->size);
359 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
360 object->comm, object->pid, object->jiffies,
361 msecs_age / 1000, msecs_age % 1000);
362 hex_dump_object(seq, object);
363 seq_printf(seq, " backtrace:\n");
365 for (i = 0; i < object->trace_len; i++) {
366 void *ptr = (void *)object->trace[i];
367 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
372 * Print the kmemleak_object information. This function is used mainly for
373 * debugging special cases when kmemleak operations. It must be called with
374 * the object->lock held.
376 static void dump_object_info(struct kmemleak_object *object)
378 struct stack_trace trace;
380 trace.nr_entries = object->trace_len;
381 trace.entries = object->trace;
383 pr_notice("Object 0x%08lx (size %zu):\n",
384 object->pointer, object->size);
385 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
386 object->comm, object->pid, object->jiffies);
387 pr_notice(" min_count = %d\n", object->min_count);
388 pr_notice(" count = %d\n", object->count);
389 pr_notice(" flags = 0x%lx\n", object->flags);
390 pr_notice(" checksum = %d\n", object->checksum);
391 pr_notice(" backtrace:\n");
392 print_stack_trace(&trace, 4);
396 * Look-up a memory block metadata (kmemleak_object) in the object search
397 * tree based on a pointer value. If alias is 0, only values pointing to the
398 * beginning of the memory block are allowed. The kmemleak_lock must be held
399 * when calling this function.
401 static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
403 struct rb_node *rb = object_tree_root.rb_node;
405 while (rb) {
406 struct kmemleak_object *object =
407 rb_entry(rb, struct kmemleak_object, rb_node);
408 if (ptr < object->pointer)
409 rb = object->rb_node.rb_left;
410 else if (object->pointer + object->size <= ptr)
411 rb = object->rb_node.rb_right;
412 else if (object->pointer == ptr || alias)
413 return object;
414 else {
415 kmemleak_warn("Found object by alias at 0x%08lx\n",
416 ptr);
417 dump_object_info(object);
418 break;
421 return NULL;
425 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
426 * that once an object's use_count reached 0, the RCU freeing was already
427 * registered and the object should no longer be used. This function must be
428 * called under the protection of rcu_read_lock().
430 static int get_object(struct kmemleak_object *object)
432 return atomic_inc_not_zero(&object->use_count);
436 * RCU callback to free a kmemleak_object.
438 static void free_object_rcu(struct rcu_head *rcu)
440 struct hlist_node *tmp;
441 struct kmemleak_scan_area *area;
442 struct kmemleak_object *object =
443 container_of(rcu, struct kmemleak_object, rcu);
446 * Once use_count is 0 (guaranteed by put_object), there is no other
447 * code accessing this object, hence no need for locking.
449 hlist_for_each_entry_safe(area, tmp, &object->area_list, node) {
450 hlist_del(&area->node);
451 kmem_cache_free(scan_area_cache, area);
453 kmem_cache_free(object_cache, object);
457 * Decrement the object use_count. Once the count is 0, free the object using
458 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
459 * delete_object() path, the delayed RCU freeing ensures that there is no
460 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
461 * is also possible.
463 static void put_object(struct kmemleak_object *object)
465 if (!atomic_dec_and_test(&object->use_count))
466 return;
468 /* should only get here after delete_object was called */
469 WARN_ON(object->flags & OBJECT_ALLOCATED);
471 call_rcu(&object->rcu, free_object_rcu);
475 * Look up an object in the object search tree and increase its use_count.
477 static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
479 unsigned long flags;
480 struct kmemleak_object *object = NULL;
482 rcu_read_lock();
483 read_lock_irqsave(&kmemleak_lock, flags);
484 if (ptr >= min_addr && ptr < max_addr)
485 object = lookup_object(ptr, alias);
486 read_unlock_irqrestore(&kmemleak_lock, flags);
488 /* check whether the object is still available */
489 if (object && !get_object(object))
490 object = NULL;
491 rcu_read_unlock();
493 return object;
497 * Save stack trace to the given array of MAX_TRACE size.
499 static int __save_stack_trace(unsigned long *trace)
501 struct stack_trace stack_trace;
503 stack_trace.max_entries = MAX_TRACE;
504 stack_trace.nr_entries = 0;
505 stack_trace.entries = trace;
506 stack_trace.skip = 2;
507 save_stack_trace(&stack_trace);
509 return stack_trace.nr_entries;
513 * Create the metadata (struct kmemleak_object) corresponding to an allocated
514 * memory block and add it to the object_list and object_tree_root.
516 static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
517 int min_count, gfp_t gfp)
519 unsigned long flags;
520 struct kmemleak_object *object, *parent;
521 struct rb_node **link, *rb_parent;
523 object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
524 if (!object) {
525 pr_warning("Cannot allocate a kmemleak_object structure\n");
526 kmemleak_disable();
527 return NULL;
530 INIT_LIST_HEAD(&object->object_list);
531 INIT_LIST_HEAD(&object->gray_list);
532 INIT_HLIST_HEAD(&object->area_list);
533 spin_lock_init(&object->lock);
534 atomic_set(&object->use_count, 1);
535 object->flags = OBJECT_ALLOCATED;
536 object->pointer = ptr;
537 object->size = size;
538 object->min_count = min_count;
539 object->count = 0; /* white color initially */
540 object->jiffies = jiffies;
541 object->checksum = 0;
543 /* task information */
544 if (in_irq()) {
545 object->pid = 0;
546 strncpy(object->comm, "hardirq", sizeof(object->comm));
547 } else if (in_softirq()) {
548 object->pid = 0;
549 strncpy(object->comm, "softirq", sizeof(object->comm));
550 } else {
551 object->pid = current->pid;
553 * There is a small chance of a race with set_task_comm(),
554 * however using get_task_comm() here may cause locking
555 * dependency issues with current->alloc_lock. In the worst
556 * case, the command line is not correct.
558 strncpy(object->comm, current->comm, sizeof(object->comm));
561 /* kernel backtrace */
562 object->trace_len = __save_stack_trace(object->trace);
564 write_lock_irqsave(&kmemleak_lock, flags);
566 min_addr = min(min_addr, ptr);
567 max_addr = max(max_addr, ptr + size);
568 link = &object_tree_root.rb_node;
569 rb_parent = NULL;
570 while (*link) {
571 rb_parent = *link;
572 parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
573 if (ptr + size <= parent->pointer)
574 link = &parent->rb_node.rb_left;
575 else if (parent->pointer + parent->size <= ptr)
576 link = &parent->rb_node.rb_right;
577 else {
578 kmemleak_stop("Cannot insert 0x%lx into the object "
579 "search tree (overlaps existing)\n",
580 ptr);
581 kmem_cache_free(object_cache, object);
582 object = parent;
583 spin_lock(&object->lock);
584 dump_object_info(object);
585 spin_unlock(&object->lock);
586 goto out;
589 rb_link_node(&object->rb_node, rb_parent, link);
590 rb_insert_color(&object->rb_node, &object_tree_root);
592 list_add_tail_rcu(&object->object_list, &object_list);
593 out:
594 write_unlock_irqrestore(&kmemleak_lock, flags);
595 return object;
599 * Remove the metadata (struct kmemleak_object) for a memory block from the
600 * object_list and object_tree_root and decrement its use_count.
602 static void __delete_object(struct kmemleak_object *object)
604 unsigned long flags;
606 write_lock_irqsave(&kmemleak_lock, flags);
607 rb_erase(&object->rb_node, &object_tree_root);
608 list_del_rcu(&object->object_list);
609 write_unlock_irqrestore(&kmemleak_lock, flags);
611 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
612 WARN_ON(atomic_read(&object->use_count) < 2);
615 * Locking here also ensures that the corresponding memory block
616 * cannot be freed when it is being scanned.
618 spin_lock_irqsave(&object->lock, flags);
619 object->flags &= ~OBJECT_ALLOCATED;
620 spin_unlock_irqrestore(&object->lock, flags);
621 put_object(object);
625 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
626 * delete it.
628 static void delete_object_full(unsigned long ptr)
630 struct kmemleak_object *object;
632 object = find_and_get_object(ptr, 0);
633 if (!object) {
634 #ifdef DEBUG
635 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
636 ptr);
637 #endif
638 return;
640 __delete_object(object);
641 put_object(object);
645 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
646 * delete it. If the memory block is partially freed, the function may create
647 * additional metadata for the remaining parts of the block.
649 static void delete_object_part(unsigned long ptr, size_t size)
651 struct kmemleak_object *object;
652 unsigned long start, end;
654 object = find_and_get_object(ptr, 1);
655 if (!object) {
656 #ifdef DEBUG
657 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
658 "(size %zu)\n", ptr, size);
659 #endif
660 return;
662 __delete_object(object);
665 * Create one or two objects that may result from the memory block
666 * split. Note that partial freeing is only done by free_bootmem() and
667 * this happens before kmemleak_init() is called. The path below is
668 * only executed during early log recording in kmemleak_init(), so
669 * GFP_KERNEL is enough.
671 start = object->pointer;
672 end = object->pointer + object->size;
673 if (ptr > start)
674 create_object(start, ptr - start, object->min_count,
675 GFP_KERNEL);
676 if (ptr + size < end)
677 create_object(ptr + size, end - ptr - size, object->min_count,
678 GFP_KERNEL);
680 put_object(object);
683 static void __paint_it(struct kmemleak_object *object, int color)
685 object->min_count = color;
686 if (color == KMEMLEAK_BLACK)
687 object->flags |= OBJECT_NO_SCAN;
690 static void paint_it(struct kmemleak_object *object, int color)
692 unsigned long flags;
694 spin_lock_irqsave(&object->lock, flags);
695 __paint_it(object, color);
696 spin_unlock_irqrestore(&object->lock, flags);
699 static void paint_ptr(unsigned long ptr, int color)
701 struct kmemleak_object *object;
703 object = find_and_get_object(ptr, 0);
704 if (!object) {
705 kmemleak_warn("Trying to color unknown object "
706 "at 0x%08lx as %s\n", ptr,
707 (color == KMEMLEAK_GREY) ? "Grey" :
708 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
709 return;
711 paint_it(object, color);
712 put_object(object);
716 * Mark an object permanently as gray-colored so that it can no longer be
717 * reported as a leak. This is used in general to mark a false positive.
719 static void make_gray_object(unsigned long ptr)
721 paint_ptr(ptr, KMEMLEAK_GREY);
725 * Mark the object as black-colored so that it is ignored from scans and
726 * reporting.
728 static void make_black_object(unsigned long ptr)
730 paint_ptr(ptr, KMEMLEAK_BLACK);
734 * Add a scanning area to the object. If at least one such area is added,
735 * kmemleak will only scan these ranges rather than the whole memory block.
737 static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
739 unsigned long flags;
740 struct kmemleak_object *object;
741 struct kmemleak_scan_area *area;
743 object = find_and_get_object(ptr, 1);
744 if (!object) {
745 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
746 ptr);
747 return;
750 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
751 if (!area) {
752 pr_warning("Cannot allocate a scan area\n");
753 goto out;
756 spin_lock_irqsave(&object->lock, flags);
757 if (size == SIZE_MAX) {
758 size = object->pointer + object->size - ptr;
759 } else if (ptr + size > object->pointer + object->size) {
760 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
761 dump_object_info(object);
762 kmem_cache_free(scan_area_cache, area);
763 goto out_unlock;
766 INIT_HLIST_NODE(&area->node);
767 area->start = ptr;
768 area->size = size;
770 hlist_add_head(&area->node, &object->area_list);
771 out_unlock:
772 spin_unlock_irqrestore(&object->lock, flags);
773 out:
774 put_object(object);
778 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
779 * pointer. Such object will not be scanned by kmemleak but references to it
780 * are searched.
782 static void object_no_scan(unsigned long ptr)
784 unsigned long flags;
785 struct kmemleak_object *object;
787 object = find_and_get_object(ptr, 0);
788 if (!object) {
789 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
790 return;
793 spin_lock_irqsave(&object->lock, flags);
794 object->flags |= OBJECT_NO_SCAN;
795 spin_unlock_irqrestore(&object->lock, flags);
796 put_object(object);
800 * Log an early kmemleak_* call to the early_log buffer. These calls will be
801 * processed later once kmemleak is fully initialized.
803 static void __init log_early(int op_type, const void *ptr, size_t size,
804 int min_count)
806 unsigned long flags;
807 struct early_log *log;
809 if (kmemleak_error) {
810 /* kmemleak stopped recording, just count the requests */
811 crt_early_log++;
812 return;
815 if (crt_early_log >= ARRAY_SIZE(early_log)) {
816 kmemleak_disable();
817 return;
821 * There is no need for locking since the kernel is still in UP mode
822 * at this stage. Disabling the IRQs is enough.
824 local_irq_save(flags);
825 log = &early_log[crt_early_log];
826 log->op_type = op_type;
827 log->ptr = ptr;
828 log->size = size;
829 log->min_count = min_count;
830 log->trace_len = __save_stack_trace(log->trace);
831 crt_early_log++;
832 local_irq_restore(flags);
836 * Log an early allocated block and populate the stack trace.
838 static void early_alloc(struct early_log *log)
840 struct kmemleak_object *object;
841 unsigned long flags;
842 int i;
844 if (!kmemleak_enabled || !log->ptr || IS_ERR(log->ptr))
845 return;
848 * RCU locking needed to ensure object is not freed via put_object().
850 rcu_read_lock();
851 object = create_object((unsigned long)log->ptr, log->size,
852 log->min_count, GFP_ATOMIC);
853 if (!object)
854 goto out;
855 spin_lock_irqsave(&object->lock, flags);
856 for (i = 0; i < log->trace_len; i++)
857 object->trace[i] = log->trace[i];
858 object->trace_len = log->trace_len;
859 spin_unlock_irqrestore(&object->lock, flags);
860 out:
861 rcu_read_unlock();
865 * Log an early allocated block and populate the stack trace.
867 static void early_alloc_percpu(struct early_log *log)
869 unsigned int cpu;
870 const void __percpu *ptr = log->ptr;
872 for_each_possible_cpu(cpu) {
873 log->ptr = per_cpu_ptr(ptr, cpu);
874 early_alloc(log);
879 * kmemleak_alloc - register a newly allocated object
880 * @ptr: pointer to beginning of the object
881 * @size: size of the object
882 * @min_count: minimum number of references to this object. If during memory
883 * scanning a number of references less than @min_count is found,
884 * the object is reported as a memory leak. If @min_count is 0,
885 * the object is never reported as a leak. If @min_count is -1,
886 * the object is ignored (not scanned and not reported as a leak)
887 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
889 * This function is called from the kernel allocators when a new object
890 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
892 void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
893 gfp_t gfp)
895 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
897 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
898 create_object((unsigned long)ptr, size, min_count, gfp);
899 else if (kmemleak_early_log)
900 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
902 EXPORT_SYMBOL_GPL(kmemleak_alloc);
905 * kmemleak_alloc_percpu - register a newly allocated __percpu object
906 * @ptr: __percpu pointer to beginning of the object
907 * @size: size of the object
909 * This function is called from the kernel percpu allocator when a new object
910 * (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL
911 * allocation.
913 void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size)
915 unsigned int cpu;
917 pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
920 * Percpu allocations are only scanned and not reported as leaks
921 * (min_count is set to 0).
923 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
924 for_each_possible_cpu(cpu)
925 create_object((unsigned long)per_cpu_ptr(ptr, cpu),
926 size, 0, GFP_KERNEL);
927 else if (kmemleak_early_log)
928 log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
930 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
933 * kmemleak_free - unregister a previously registered object
934 * @ptr: pointer to beginning of the object
936 * This function is called from the kernel allocators when an object (memory
937 * block) is freed (kmem_cache_free, kfree, vfree etc.).
939 void __ref kmemleak_free(const void *ptr)
941 pr_debug("%s(0x%p)\n", __func__, ptr);
943 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
944 delete_object_full((unsigned long)ptr);
945 else if (kmemleak_early_log)
946 log_early(KMEMLEAK_FREE, ptr, 0, 0);
948 EXPORT_SYMBOL_GPL(kmemleak_free);
951 * kmemleak_free_part - partially unregister a previously registered object
952 * @ptr: pointer to the beginning or inside the object. This also
953 * represents the start of the range to be freed
954 * @size: size to be unregistered
956 * This function is called when only a part of a memory block is freed
957 * (usually from the bootmem allocator).
959 void __ref kmemleak_free_part(const void *ptr, size_t size)
961 pr_debug("%s(0x%p)\n", __func__, ptr);
963 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
964 delete_object_part((unsigned long)ptr, size);
965 else if (kmemleak_early_log)
966 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
968 EXPORT_SYMBOL_GPL(kmemleak_free_part);
971 * kmemleak_free_percpu - unregister a previously registered __percpu object
972 * @ptr: __percpu pointer to beginning of the object
974 * This function is called from the kernel percpu allocator when an object
975 * (memory block) is freed (free_percpu).
977 void __ref kmemleak_free_percpu(const void __percpu *ptr)
979 unsigned int cpu;
981 pr_debug("%s(0x%p)\n", __func__, ptr);
983 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
984 for_each_possible_cpu(cpu)
985 delete_object_full((unsigned long)per_cpu_ptr(ptr,
986 cpu));
987 else if (kmemleak_early_log)
988 log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
990 EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
993 * kmemleak_not_leak - mark an allocated object as false positive
994 * @ptr: pointer to beginning of the object
996 * Calling this function on an object will cause the memory block to no longer
997 * be reported as leak and always be scanned.
999 void __ref kmemleak_not_leak(const void *ptr)
1001 pr_debug("%s(0x%p)\n", __func__, ptr);
1003 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1004 make_gray_object((unsigned long)ptr);
1005 else if (kmemleak_early_log)
1006 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
1008 EXPORT_SYMBOL(kmemleak_not_leak);
1011 * kmemleak_ignore - ignore an allocated object
1012 * @ptr: pointer to beginning of the object
1014 * Calling this function on an object will cause the memory block to be
1015 * ignored (not scanned and not reported as a leak). This is usually done when
1016 * it is known that the corresponding block is not a leak and does not contain
1017 * any references to other allocated memory blocks.
1019 void __ref kmemleak_ignore(const void *ptr)
1021 pr_debug("%s(0x%p)\n", __func__, ptr);
1023 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1024 make_black_object((unsigned long)ptr);
1025 else if (kmemleak_early_log)
1026 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
1028 EXPORT_SYMBOL(kmemleak_ignore);
1031 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1032 * @ptr: pointer to beginning or inside the object. This also
1033 * represents the start of the scan area
1034 * @size: size of the scan area
1035 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1037 * This function is used when it is known that only certain parts of an object
1038 * contain references to other objects. Kmemleak will only scan these areas
1039 * reducing the number false negatives.
1041 void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
1043 pr_debug("%s(0x%p)\n", __func__, ptr);
1045 if (kmemleak_enabled && ptr && size && !IS_ERR(ptr))
1046 add_scan_area((unsigned long)ptr, size, gfp);
1047 else if (kmemleak_early_log)
1048 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
1050 EXPORT_SYMBOL(kmemleak_scan_area);
1053 * kmemleak_no_scan - do not scan an allocated object
1054 * @ptr: pointer to beginning of the object
1056 * This function notifies kmemleak not to scan the given memory block. Useful
1057 * in situations where it is known that the given object does not contain any
1058 * references to other objects. Kmemleak will not scan such objects reducing
1059 * the number of false negatives.
1061 void __ref kmemleak_no_scan(const void *ptr)
1063 pr_debug("%s(0x%p)\n", __func__, ptr);
1065 if (kmemleak_enabled && ptr && !IS_ERR(ptr))
1066 object_no_scan((unsigned long)ptr);
1067 else if (kmemleak_early_log)
1068 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
1070 EXPORT_SYMBOL(kmemleak_no_scan);
1073 * Update an object's checksum and return true if it was modified.
1075 static bool update_checksum(struct kmemleak_object *object)
1077 u32 old_csum = object->checksum;
1079 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
1080 return false;
1082 object->checksum = crc32(0, (void *)object->pointer, object->size);
1083 return object->checksum != old_csum;
1087 * Memory scanning is a long process and it needs to be interruptable. This
1088 * function checks whether such interrupt condition occurred.
1090 static int scan_should_stop(void)
1092 if (!kmemleak_enabled)
1093 return 1;
1096 * This function may be called from either process or kthread context,
1097 * hence the need to check for both stop conditions.
1099 if (current->mm)
1100 return signal_pending(current);
1101 else
1102 return kthread_should_stop();
1104 return 0;
1108 * Scan a memory block (exclusive range) for valid pointers and add those
1109 * found to the gray list.
1111 static void scan_block(void *_start, void *_end,
1112 struct kmemleak_object *scanned, int allow_resched)
1114 unsigned long *ptr;
1115 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1116 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1118 for (ptr = start; ptr < end; ptr++) {
1119 struct kmemleak_object *object;
1120 unsigned long flags;
1121 unsigned long pointer;
1123 if (allow_resched)
1124 cond_resched();
1125 if (scan_should_stop())
1126 break;
1128 /* don't scan uninitialized memory */
1129 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1130 BYTES_PER_POINTER))
1131 continue;
1133 pointer = *ptr;
1135 object = find_and_get_object(pointer, 1);
1136 if (!object)
1137 continue;
1138 if (object == scanned) {
1139 /* self referenced, ignore */
1140 put_object(object);
1141 continue;
1145 * Avoid the lockdep recursive warning on object->lock being
1146 * previously acquired in scan_object(). These locks are
1147 * enclosed by scan_mutex.
1149 spin_lock_irqsave_nested(&object->lock, flags,
1150 SINGLE_DEPTH_NESTING);
1151 if (!color_white(object)) {
1152 /* non-orphan, ignored or new */
1153 spin_unlock_irqrestore(&object->lock, flags);
1154 put_object(object);
1155 continue;
1159 * Increase the object's reference count (number of pointers
1160 * to the memory block). If this count reaches the required
1161 * minimum, the object's color will become gray and it will be
1162 * added to the gray_list.
1164 object->count++;
1165 if (color_gray(object)) {
1166 list_add_tail(&object->gray_list, &gray_list);
1167 spin_unlock_irqrestore(&object->lock, flags);
1168 continue;
1171 spin_unlock_irqrestore(&object->lock, flags);
1172 put_object(object);
1177 * Scan a memory block corresponding to a kmemleak_object. A condition is
1178 * that object->use_count >= 1.
1180 static void scan_object(struct kmemleak_object *object)
1182 struct kmemleak_scan_area *area;
1183 unsigned long flags;
1186 * Once the object->lock is acquired, the corresponding memory block
1187 * cannot be freed (the same lock is acquired in delete_object).
1189 spin_lock_irqsave(&object->lock, flags);
1190 if (object->flags & OBJECT_NO_SCAN)
1191 goto out;
1192 if (!(object->flags & OBJECT_ALLOCATED))
1193 /* already freed object */
1194 goto out;
1195 if (hlist_empty(&object->area_list)) {
1196 void *start = (void *)object->pointer;
1197 void *end = (void *)(object->pointer + object->size);
1199 while (start < end && (object->flags & OBJECT_ALLOCATED) &&
1200 !(object->flags & OBJECT_NO_SCAN)) {
1201 scan_block(start, min(start + MAX_SCAN_SIZE, end),
1202 object, 0);
1203 start += MAX_SCAN_SIZE;
1205 spin_unlock_irqrestore(&object->lock, flags);
1206 cond_resched();
1207 spin_lock_irqsave(&object->lock, flags);
1209 } else
1210 hlist_for_each_entry(area, &object->area_list, node)
1211 scan_block((void *)area->start,
1212 (void *)(area->start + area->size),
1213 object, 0);
1214 out:
1215 spin_unlock_irqrestore(&object->lock, flags);
1219 * Scan the objects already referenced (gray objects). More objects will be
1220 * referenced and, if there are no memory leaks, all the objects are scanned.
1222 static void scan_gray_list(void)
1224 struct kmemleak_object *object, *tmp;
1227 * The list traversal is safe for both tail additions and removals
1228 * from inside the loop. The kmemleak objects cannot be freed from
1229 * outside the loop because their use_count was incremented.
1231 object = list_entry(gray_list.next, typeof(*object), gray_list);
1232 while (&object->gray_list != &gray_list) {
1233 cond_resched();
1235 /* may add new objects to the list */
1236 if (!scan_should_stop())
1237 scan_object(object);
1239 tmp = list_entry(object->gray_list.next, typeof(*object),
1240 gray_list);
1242 /* remove the object from the list and release it */
1243 list_del(&object->gray_list);
1244 put_object(object);
1246 object = tmp;
1248 WARN_ON(!list_empty(&gray_list));
1252 * Scan data sections and all the referenced memory blocks allocated via the
1253 * kernel's standard allocators. This function must be called with the
1254 * scan_mutex held.
1256 static void kmemleak_scan(void)
1258 unsigned long flags;
1259 struct kmemleak_object *object;
1260 int i;
1261 int new_leaks = 0;
1263 jiffies_last_scan = jiffies;
1265 /* prepare the kmemleak_object's */
1266 rcu_read_lock();
1267 list_for_each_entry_rcu(object, &object_list, object_list) {
1268 spin_lock_irqsave(&object->lock, flags);
1269 #ifdef DEBUG
1271 * With a few exceptions there should be a maximum of
1272 * 1 reference to any object at this point.
1274 if (atomic_read(&object->use_count) > 1) {
1275 pr_debug("object->use_count = %d\n",
1276 atomic_read(&object->use_count));
1277 dump_object_info(object);
1279 #endif
1280 /* reset the reference count (whiten the object) */
1281 object->count = 0;
1282 if (color_gray(object) && get_object(object))
1283 list_add_tail(&object->gray_list, &gray_list);
1285 spin_unlock_irqrestore(&object->lock, flags);
1287 rcu_read_unlock();
1289 /* data/bss scanning */
1290 scan_block(_sdata, _edata, NULL, 1);
1291 scan_block(__bss_start, __bss_stop, NULL, 1);
1293 #ifdef CONFIG_SMP
1294 /* per-cpu sections scanning */
1295 for_each_possible_cpu(i)
1296 scan_block(__per_cpu_start + per_cpu_offset(i),
1297 __per_cpu_end + per_cpu_offset(i), NULL, 1);
1298 #endif
1301 * Struct page scanning for each node.
1303 lock_memory_hotplug();
1304 for_each_online_node(i) {
1305 unsigned long start_pfn = node_start_pfn(i);
1306 unsigned long end_pfn = node_end_pfn(i);
1307 unsigned long pfn;
1309 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1310 struct page *page;
1312 if (!pfn_valid(pfn))
1313 continue;
1314 page = pfn_to_page(pfn);
1315 /* only scan if page is in use */
1316 if (page_count(page) == 0)
1317 continue;
1318 scan_block(page, page + 1, NULL, 1);
1321 unlock_memory_hotplug();
1324 * Scanning the task stacks (may introduce false negatives).
1326 if (kmemleak_stack_scan) {
1327 struct task_struct *p, *g;
1329 read_lock(&tasklist_lock);
1330 do_each_thread(g, p) {
1331 scan_block(task_stack_page(p), task_stack_page(p) +
1332 THREAD_SIZE, NULL, 0);
1333 } while_each_thread(g, p);
1334 read_unlock(&tasklist_lock);
1338 * Scan the objects already referenced from the sections scanned
1339 * above.
1341 scan_gray_list();
1344 * Check for new or unreferenced objects modified since the previous
1345 * scan and color them gray until the next scan.
1347 rcu_read_lock();
1348 list_for_each_entry_rcu(object, &object_list, object_list) {
1349 spin_lock_irqsave(&object->lock, flags);
1350 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1351 && update_checksum(object) && get_object(object)) {
1352 /* color it gray temporarily */
1353 object->count = object->min_count;
1354 list_add_tail(&object->gray_list, &gray_list);
1356 spin_unlock_irqrestore(&object->lock, flags);
1358 rcu_read_unlock();
1361 * Re-scan the gray list for modified unreferenced objects.
1363 scan_gray_list();
1366 * If scanning was stopped do not report any new unreferenced objects.
1368 if (scan_should_stop())
1369 return;
1372 * Scanning result reporting.
1374 rcu_read_lock();
1375 list_for_each_entry_rcu(object, &object_list, object_list) {
1376 spin_lock_irqsave(&object->lock, flags);
1377 if (unreferenced_object(object) &&
1378 !(object->flags & OBJECT_REPORTED)) {
1379 object->flags |= OBJECT_REPORTED;
1380 new_leaks++;
1382 spin_unlock_irqrestore(&object->lock, flags);
1384 rcu_read_unlock();
1386 if (new_leaks) {
1387 kmemleak_found_leaks = true;
1389 pr_info("%d new suspected memory leaks (see "
1390 "/sys/kernel/debug/kmemleak)\n", new_leaks);
1396 * Thread function performing automatic memory scanning. Unreferenced objects
1397 * at the end of a memory scan are reported but only the first time.
1399 static int kmemleak_scan_thread(void *arg)
1401 static int first_run = 1;
1403 pr_info("Automatic memory scanning thread started\n");
1404 set_user_nice(current, 10);
1407 * Wait before the first scan to allow the system to fully initialize.
1409 if (first_run) {
1410 first_run = 0;
1411 ssleep(SECS_FIRST_SCAN);
1414 while (!kthread_should_stop()) {
1415 signed long timeout = jiffies_scan_wait;
1417 mutex_lock(&scan_mutex);
1418 kmemleak_scan();
1419 mutex_unlock(&scan_mutex);
1421 /* wait before the next scan */
1422 while (timeout && !kthread_should_stop())
1423 timeout = schedule_timeout_interruptible(timeout);
1426 pr_info("Automatic memory scanning thread ended\n");
1428 return 0;
1432 * Start the automatic memory scanning thread. This function must be called
1433 * with the scan_mutex held.
1435 static void start_scan_thread(void)
1437 if (scan_thread)
1438 return;
1439 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1440 if (IS_ERR(scan_thread)) {
1441 pr_warning("Failed to create the scan thread\n");
1442 scan_thread = NULL;
1447 * Stop the automatic memory scanning thread. This function must be called
1448 * with the scan_mutex held.
1450 static void stop_scan_thread(void)
1452 if (scan_thread) {
1453 kthread_stop(scan_thread);
1454 scan_thread = NULL;
1459 * Iterate over the object_list and return the first valid object at or after
1460 * the required position with its use_count incremented. The function triggers
1461 * a memory scanning when the pos argument points to the first position.
1463 static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1465 struct kmemleak_object *object;
1466 loff_t n = *pos;
1467 int err;
1469 err = mutex_lock_interruptible(&scan_mutex);
1470 if (err < 0)
1471 return ERR_PTR(err);
1473 rcu_read_lock();
1474 list_for_each_entry_rcu(object, &object_list, object_list) {
1475 if (n-- > 0)
1476 continue;
1477 if (get_object(object))
1478 goto out;
1480 object = NULL;
1481 out:
1482 return object;
1486 * Return the next object in the object_list. The function decrements the
1487 * use_count of the previous object and increases that of the next one.
1489 static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1491 struct kmemleak_object *prev_obj = v;
1492 struct kmemleak_object *next_obj = NULL;
1493 struct kmemleak_object *obj = prev_obj;
1495 ++(*pos);
1497 list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
1498 if (get_object(obj)) {
1499 next_obj = obj;
1500 break;
1504 put_object(prev_obj);
1505 return next_obj;
1509 * Decrement the use_count of the last object required, if any.
1511 static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1513 if (!IS_ERR(v)) {
1515 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1516 * waiting was interrupted, so only release it if !IS_ERR.
1518 rcu_read_unlock();
1519 mutex_unlock(&scan_mutex);
1520 if (v)
1521 put_object(v);
1526 * Print the information for an unreferenced object to the seq file.
1528 static int kmemleak_seq_show(struct seq_file *seq, void *v)
1530 struct kmemleak_object *object = v;
1531 unsigned long flags;
1533 spin_lock_irqsave(&object->lock, flags);
1534 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
1535 print_unreferenced(seq, object);
1536 spin_unlock_irqrestore(&object->lock, flags);
1537 return 0;
1540 static const struct seq_operations kmemleak_seq_ops = {
1541 .start = kmemleak_seq_start,
1542 .next = kmemleak_seq_next,
1543 .stop = kmemleak_seq_stop,
1544 .show = kmemleak_seq_show,
1547 static int kmemleak_open(struct inode *inode, struct file *file)
1549 return seq_open(file, &kmemleak_seq_ops);
1552 static int dump_str_object_info(const char *str)
1554 unsigned long flags;
1555 struct kmemleak_object *object;
1556 unsigned long addr;
1558 if (kstrtoul(str, 0, &addr))
1559 return -EINVAL;
1560 object = find_and_get_object(addr, 0);
1561 if (!object) {
1562 pr_info("Unknown object at 0x%08lx\n", addr);
1563 return -EINVAL;
1566 spin_lock_irqsave(&object->lock, flags);
1567 dump_object_info(object);
1568 spin_unlock_irqrestore(&object->lock, flags);
1570 put_object(object);
1571 return 0;
1575 * We use grey instead of black to ensure we can do future scans on the same
1576 * objects. If we did not do future scans these black objects could
1577 * potentially contain references to newly allocated objects in the future and
1578 * we'd end up with false positives.
1580 static void kmemleak_clear(void)
1582 struct kmemleak_object *object;
1583 unsigned long flags;
1585 rcu_read_lock();
1586 list_for_each_entry_rcu(object, &object_list, object_list) {
1587 spin_lock_irqsave(&object->lock, flags);
1588 if ((object->flags & OBJECT_REPORTED) &&
1589 unreferenced_object(object))
1590 __paint_it(object, KMEMLEAK_GREY);
1591 spin_unlock_irqrestore(&object->lock, flags);
1593 rcu_read_unlock();
1595 kmemleak_found_leaks = false;
1598 static void __kmemleak_do_cleanup(void);
1601 * File write operation to configure kmemleak at run-time. The following
1602 * commands can be written to the /sys/kernel/debug/kmemleak file:
1603 * off - disable kmemleak (irreversible)
1604 * stack=on - enable the task stacks scanning
1605 * stack=off - disable the tasks stacks scanning
1606 * scan=on - start the automatic memory scanning thread
1607 * scan=off - stop the automatic memory scanning thread
1608 * scan=... - set the automatic memory scanning period in seconds (0 to
1609 * disable it)
1610 * scan - trigger a memory scan
1611 * clear - mark all current reported unreferenced kmemleak objects as
1612 * grey to ignore printing them, or free all kmemleak objects
1613 * if kmemleak has been disabled.
1614 * dump=... - dump information about the object found at the given address
1616 static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1617 size_t size, loff_t *ppos)
1619 char buf[64];
1620 int buf_size;
1621 int ret;
1623 buf_size = min(size, (sizeof(buf) - 1));
1624 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1625 return -EFAULT;
1626 buf[buf_size] = 0;
1628 ret = mutex_lock_interruptible(&scan_mutex);
1629 if (ret < 0)
1630 return ret;
1632 if (strncmp(buf, "clear", 5) == 0) {
1633 if (kmemleak_enabled)
1634 kmemleak_clear();
1635 else
1636 __kmemleak_do_cleanup();
1637 goto out;
1640 if (!kmemleak_enabled) {
1641 ret = -EBUSY;
1642 goto out;
1645 if (strncmp(buf, "off", 3) == 0)
1646 kmemleak_disable();
1647 else if (strncmp(buf, "stack=on", 8) == 0)
1648 kmemleak_stack_scan = 1;
1649 else if (strncmp(buf, "stack=off", 9) == 0)
1650 kmemleak_stack_scan = 0;
1651 else if (strncmp(buf, "scan=on", 7) == 0)
1652 start_scan_thread();
1653 else if (strncmp(buf, "scan=off", 8) == 0)
1654 stop_scan_thread();
1655 else if (strncmp(buf, "scan=", 5) == 0) {
1656 unsigned long secs;
1658 ret = kstrtoul(buf + 5, 0, &secs);
1659 if (ret < 0)
1660 goto out;
1661 stop_scan_thread();
1662 if (secs) {
1663 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1664 start_scan_thread();
1666 } else if (strncmp(buf, "scan", 4) == 0)
1667 kmemleak_scan();
1668 else if (strncmp(buf, "dump=", 5) == 0)
1669 ret = dump_str_object_info(buf + 5);
1670 else
1671 ret = -EINVAL;
1673 out:
1674 mutex_unlock(&scan_mutex);
1675 if (ret < 0)
1676 return ret;
1678 /* ignore the rest of the buffer, only one command at a time */
1679 *ppos += size;
1680 return size;
1683 static const struct file_operations kmemleak_fops = {
1684 .owner = THIS_MODULE,
1685 .open = kmemleak_open,
1686 .read = seq_read,
1687 .write = kmemleak_write,
1688 .llseek = seq_lseek,
1689 .release = seq_release,
1692 static void __kmemleak_do_cleanup(void)
1694 struct kmemleak_object *object;
1696 rcu_read_lock();
1697 list_for_each_entry_rcu(object, &object_list, object_list)
1698 delete_object_full(object->pointer);
1699 rcu_read_unlock();
1703 * Stop the memory scanning thread and free the kmemleak internal objects if
1704 * no previous scan thread (otherwise, kmemleak may still have some useful
1705 * information on memory leaks).
1707 static void kmemleak_do_cleanup(struct work_struct *work)
1709 mutex_lock(&scan_mutex);
1710 stop_scan_thread();
1712 if (!kmemleak_found_leaks)
1713 __kmemleak_do_cleanup();
1714 else
1715 pr_info("Kmemleak disabled without freeing internal data. "
1716 "Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\"\n");
1717 mutex_unlock(&scan_mutex);
1720 static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
1723 * Disable kmemleak. No memory allocation/freeing will be traced once this
1724 * function is called. Disabling kmemleak is an irreversible operation.
1726 static void kmemleak_disable(void)
1728 /* atomically check whether it was already invoked */
1729 if (cmpxchg(&kmemleak_error, 0, 1))
1730 return;
1732 /* stop any memory operation tracing */
1733 kmemleak_enabled = 0;
1735 /* check whether it is too early for a kernel thread */
1736 if (kmemleak_initialized)
1737 schedule_work(&cleanup_work);
1739 pr_info("Kernel memory leak detector disabled\n");
1743 * Allow boot-time kmemleak disabling (enabled by default).
1745 static int kmemleak_boot_config(char *str)
1747 if (!str)
1748 return -EINVAL;
1749 if (strcmp(str, "off") == 0)
1750 kmemleak_disable();
1751 else if (strcmp(str, "on") == 0)
1752 kmemleak_skip_disable = 1;
1753 else
1754 return -EINVAL;
1755 return 0;
1757 early_param("kmemleak", kmemleak_boot_config);
1759 static void __init print_log_trace(struct early_log *log)
1761 struct stack_trace trace;
1763 trace.nr_entries = log->trace_len;
1764 trace.entries = log->trace;
1766 pr_notice("Early log backtrace:\n");
1767 print_stack_trace(&trace, 2);
1771 * Kmemleak initialization.
1773 void __init kmemleak_init(void)
1775 int i;
1776 unsigned long flags;
1778 kmemleak_early_log = 0;
1780 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1781 if (!kmemleak_skip_disable) {
1782 kmemleak_disable();
1783 return;
1785 #endif
1787 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1788 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1790 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1791 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1793 if (crt_early_log >= ARRAY_SIZE(early_log))
1794 pr_warning("Early log buffer exceeded (%d), please increase "
1795 "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log);
1797 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1798 local_irq_save(flags);
1799 if (kmemleak_error) {
1800 local_irq_restore(flags);
1801 return;
1802 } else
1803 kmemleak_enabled = 1;
1804 local_irq_restore(flags);
1807 * This is the point where tracking allocations is safe. Automatic
1808 * scanning is started during the late initcall. Add the early logged
1809 * callbacks to the kmemleak infrastructure.
1811 for (i = 0; i < crt_early_log; i++) {
1812 struct early_log *log = &early_log[i];
1814 switch (log->op_type) {
1815 case KMEMLEAK_ALLOC:
1816 early_alloc(log);
1817 break;
1818 case KMEMLEAK_ALLOC_PERCPU:
1819 early_alloc_percpu(log);
1820 break;
1821 case KMEMLEAK_FREE:
1822 kmemleak_free(log->ptr);
1823 break;
1824 case KMEMLEAK_FREE_PART:
1825 kmemleak_free_part(log->ptr, log->size);
1826 break;
1827 case KMEMLEAK_FREE_PERCPU:
1828 kmemleak_free_percpu(log->ptr);
1829 break;
1830 case KMEMLEAK_NOT_LEAK:
1831 kmemleak_not_leak(log->ptr);
1832 break;
1833 case KMEMLEAK_IGNORE:
1834 kmemleak_ignore(log->ptr);
1835 break;
1836 case KMEMLEAK_SCAN_AREA:
1837 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
1838 break;
1839 case KMEMLEAK_NO_SCAN:
1840 kmemleak_no_scan(log->ptr);
1841 break;
1842 default:
1843 kmemleak_warn("Unknown early log operation: %d\n",
1844 log->op_type);
1847 if (kmemleak_warning) {
1848 print_log_trace(log);
1849 kmemleak_warning = 0;
1855 * Late initialization function.
1857 static int __init kmemleak_late_init(void)
1859 struct dentry *dentry;
1861 kmemleak_initialized = 1;
1863 if (kmemleak_error) {
1865 * Some error occurred and kmemleak was disabled. There is a
1866 * small chance that kmemleak_disable() was called immediately
1867 * after setting kmemleak_initialized and we may end up with
1868 * two clean-up threads but serialized by scan_mutex.
1870 schedule_work(&cleanup_work);
1871 return -ENOMEM;
1874 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1875 &kmemleak_fops);
1876 if (!dentry)
1877 pr_warning("Failed to create the debugfs kmemleak file\n");
1878 mutex_lock(&scan_mutex);
1879 start_scan_thread();
1880 mutex_unlock(&scan_mutex);
1882 pr_info("Kernel memory leak detector initialized\n");
1884 return 0;
1886 late_initcall(kmemleak_late_init);