USB: gadget: atmel_usba: add DT support
[linux-2.6.git] / mm / kmemleak.c
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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 atomic_t kmemleak_enabled = ATOMIC_INIT(0);
196 /* set in the late_initcall if there were no errors */
197 static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
198 /* enables or disables early logging of the memory operations */
199 static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
200 /* set if a kmemleak warning was issued */
201 static atomic_t kmemleak_warning = ATOMIC_INIT(0);
202 /* set if a fatal kmemleak error has occurred */
203 static atomic_t kmemleak_error = ATOMIC_INIT(0);
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;
224 * Early object allocation/freeing logging. Kmemleak is initialized after the
225 * kernel allocator. However, both the kernel allocator and kmemleak may
226 * allocate memory blocks which need to be tracked. Kmemleak defines an
227 * arbitrary buffer to hold the allocation/freeing information before it is
228 * fully initialized.
231 /* kmemleak operation type for early logging */
232 enum {
233 KMEMLEAK_ALLOC,
234 KMEMLEAK_ALLOC_PERCPU,
235 KMEMLEAK_FREE,
236 KMEMLEAK_FREE_PART,
237 KMEMLEAK_FREE_PERCPU,
238 KMEMLEAK_NOT_LEAK,
239 KMEMLEAK_IGNORE,
240 KMEMLEAK_SCAN_AREA,
241 KMEMLEAK_NO_SCAN
245 * Structure holding the information passed to kmemleak callbacks during the
246 * early logging.
248 struct early_log {
249 int op_type; /* kmemleak operation type */
250 const void *ptr; /* allocated/freed memory block */
251 size_t size; /* memory block size */
252 int min_count; /* minimum reference count */
253 unsigned long trace[MAX_TRACE]; /* stack trace */
254 unsigned int trace_len; /* stack trace length */
257 /* early logging buffer and current position */
258 static struct early_log
259 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
260 static int crt_early_log __initdata;
262 static void kmemleak_disable(void);
265 * Print a warning and dump the stack trace.
267 #define kmemleak_warn(x...) do { \
268 pr_warning(x); \
269 dump_stack(); \
270 atomic_set(&kmemleak_warning, 1); \
271 } while (0)
274 * Macro invoked when a serious kmemleak condition occurred and cannot be
275 * recovered from. Kmemleak will be disabled and further allocation/freeing
276 * tracing no longer available.
278 #define kmemleak_stop(x...) do { \
279 kmemleak_warn(x); \
280 kmemleak_disable(); \
281 } while (0)
284 * Printing of the objects hex dump to the seq file. The number of lines to be
285 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
286 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
287 * with the object->lock held.
289 static void hex_dump_object(struct seq_file *seq,
290 struct kmemleak_object *object)
292 const u8 *ptr = (const u8 *)object->pointer;
293 int i, len, remaining;
294 unsigned char linebuf[HEX_ROW_SIZE * 5];
296 /* limit the number of lines to HEX_MAX_LINES */
297 remaining = len =
298 min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
300 seq_printf(seq, " hex dump (first %d bytes):\n", len);
301 for (i = 0; i < len; i += HEX_ROW_SIZE) {
302 int linelen = min(remaining, HEX_ROW_SIZE);
304 remaining -= HEX_ROW_SIZE;
305 hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
306 HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
307 HEX_ASCII);
308 seq_printf(seq, " %s\n", linebuf);
313 * Object colors, encoded with count and min_count:
314 * - white - orphan object, not enough references to it (count < min_count)
315 * - gray - not orphan, not marked as false positive (min_count == 0) or
316 * sufficient references to it (count >= min_count)
317 * - black - ignore, it doesn't contain references (e.g. text section)
318 * (min_count == -1). No function defined for this color.
319 * Newly created objects don't have any color assigned (object->count == -1)
320 * before the next memory scan when they become white.
322 static bool color_white(const struct kmemleak_object *object)
324 return object->count != KMEMLEAK_BLACK &&
325 object->count < object->min_count;
328 static bool color_gray(const struct kmemleak_object *object)
330 return object->min_count != KMEMLEAK_BLACK &&
331 object->count >= object->min_count;
335 * Objects are considered unreferenced only if their color is white, they have
336 * not be deleted and have a minimum age to avoid false positives caused by
337 * pointers temporarily stored in CPU registers.
339 static bool unreferenced_object(struct kmemleak_object *object)
341 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
342 time_before_eq(object->jiffies + jiffies_min_age,
343 jiffies_last_scan);
347 * Printing of the unreferenced objects information to the seq file. The
348 * print_unreferenced function must be called with the object->lock held.
350 static void print_unreferenced(struct seq_file *seq,
351 struct kmemleak_object *object)
353 int i;
354 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
356 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
357 object->pointer, object->size);
358 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
359 object->comm, object->pid, object->jiffies,
360 msecs_age / 1000, msecs_age % 1000);
361 hex_dump_object(seq, object);
362 seq_printf(seq, " backtrace:\n");
364 for (i = 0; i < object->trace_len; i++) {
365 void *ptr = (void *)object->trace[i];
366 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
371 * Print the kmemleak_object information. This function is used mainly for
372 * debugging special cases when kmemleak operations. It must be called with
373 * the object->lock held.
375 static void dump_object_info(struct kmemleak_object *object)
377 struct stack_trace trace;
379 trace.nr_entries = object->trace_len;
380 trace.entries = object->trace;
382 pr_notice("Object 0x%08lx (size %zu):\n",
383 object->pointer, object->size);
384 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
385 object->comm, object->pid, object->jiffies);
386 pr_notice(" min_count = %d\n", object->min_count);
387 pr_notice(" count = %d\n", object->count);
388 pr_notice(" flags = 0x%lx\n", object->flags);
389 pr_notice(" checksum = %d\n", object->checksum);
390 pr_notice(" backtrace:\n");
391 print_stack_trace(&trace, 4);
395 * Look-up a memory block metadata (kmemleak_object) in the object search
396 * tree based on a pointer value. If alias is 0, only values pointing to the
397 * beginning of the memory block are allowed. The kmemleak_lock must be held
398 * when calling this function.
400 static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
402 struct rb_node *rb = object_tree_root.rb_node;
404 while (rb) {
405 struct kmemleak_object *object =
406 rb_entry(rb, struct kmemleak_object, rb_node);
407 if (ptr < object->pointer)
408 rb = object->rb_node.rb_left;
409 else if (object->pointer + object->size <= ptr)
410 rb = object->rb_node.rb_right;
411 else if (object->pointer == ptr || alias)
412 return object;
413 else {
414 kmemleak_warn("Found object by alias at 0x%08lx\n",
415 ptr);
416 dump_object_info(object);
417 break;
420 return NULL;
424 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
425 * that once an object's use_count reached 0, the RCU freeing was already
426 * registered and the object should no longer be used. This function must be
427 * called under the protection of rcu_read_lock().
429 static int get_object(struct kmemleak_object *object)
431 return atomic_inc_not_zero(&object->use_count);
435 * RCU callback to free a kmemleak_object.
437 static void free_object_rcu(struct rcu_head *rcu)
439 struct hlist_node *tmp;
440 struct kmemleak_scan_area *area;
441 struct kmemleak_object *object =
442 container_of(rcu, struct kmemleak_object, rcu);
445 * Once use_count is 0 (guaranteed by put_object), there is no other
446 * code accessing this object, hence no need for locking.
448 hlist_for_each_entry_safe(area, tmp, &object->area_list, node) {
449 hlist_del(&area->node);
450 kmem_cache_free(scan_area_cache, area);
452 kmem_cache_free(object_cache, object);
456 * Decrement the object use_count. Once the count is 0, free the object using
457 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
458 * delete_object() path, the delayed RCU freeing ensures that there is no
459 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
460 * is also possible.
462 static void put_object(struct kmemleak_object *object)
464 if (!atomic_dec_and_test(&object->use_count))
465 return;
467 /* should only get here after delete_object was called */
468 WARN_ON(object->flags & OBJECT_ALLOCATED);
470 call_rcu(&object->rcu, free_object_rcu);
474 * Look up an object in the object search tree and increase its use_count.
476 static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
478 unsigned long flags;
479 struct kmemleak_object *object = NULL;
481 rcu_read_lock();
482 read_lock_irqsave(&kmemleak_lock, flags);
483 if (ptr >= min_addr && ptr < max_addr)
484 object = lookup_object(ptr, alias);
485 read_unlock_irqrestore(&kmemleak_lock, flags);
487 /* check whether the object is still available */
488 if (object && !get_object(object))
489 object = NULL;
490 rcu_read_unlock();
492 return object;
496 * Save stack trace to the given array of MAX_TRACE size.
498 static int __save_stack_trace(unsigned long *trace)
500 struct stack_trace stack_trace;
502 stack_trace.max_entries = MAX_TRACE;
503 stack_trace.nr_entries = 0;
504 stack_trace.entries = trace;
505 stack_trace.skip = 2;
506 save_stack_trace(&stack_trace);
508 return stack_trace.nr_entries;
512 * Create the metadata (struct kmemleak_object) corresponding to an allocated
513 * memory block and add it to the object_list and object_tree_root.
515 static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
516 int min_count, gfp_t gfp)
518 unsigned long flags;
519 struct kmemleak_object *object, *parent;
520 struct rb_node **link, *rb_parent;
522 object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
523 if (!object) {
524 pr_warning("Cannot allocate a kmemleak_object structure\n");
525 kmemleak_disable();
526 return NULL;
529 INIT_LIST_HEAD(&object->object_list);
530 INIT_LIST_HEAD(&object->gray_list);
531 INIT_HLIST_HEAD(&object->area_list);
532 spin_lock_init(&object->lock);
533 atomic_set(&object->use_count, 1);
534 object->flags = OBJECT_ALLOCATED;
535 object->pointer = ptr;
536 object->size = size;
537 object->min_count = min_count;
538 object->count = 0; /* white color initially */
539 object->jiffies = jiffies;
540 object->checksum = 0;
542 /* task information */
543 if (in_irq()) {
544 object->pid = 0;
545 strncpy(object->comm, "hardirq", sizeof(object->comm));
546 } else if (in_softirq()) {
547 object->pid = 0;
548 strncpy(object->comm, "softirq", sizeof(object->comm));
549 } else {
550 object->pid = current->pid;
552 * There is a small chance of a race with set_task_comm(),
553 * however using get_task_comm() here may cause locking
554 * dependency issues with current->alloc_lock. In the worst
555 * case, the command line is not correct.
557 strncpy(object->comm, current->comm, sizeof(object->comm));
560 /* kernel backtrace */
561 object->trace_len = __save_stack_trace(object->trace);
563 write_lock_irqsave(&kmemleak_lock, flags);
565 min_addr = min(min_addr, ptr);
566 max_addr = max(max_addr, ptr + size);
567 link = &object_tree_root.rb_node;
568 rb_parent = NULL;
569 while (*link) {
570 rb_parent = *link;
571 parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
572 if (ptr + size <= parent->pointer)
573 link = &parent->rb_node.rb_left;
574 else if (parent->pointer + parent->size <= ptr)
575 link = &parent->rb_node.rb_right;
576 else {
577 kmemleak_stop("Cannot insert 0x%lx into the object "
578 "search tree (overlaps existing)\n",
579 ptr);
580 kmem_cache_free(object_cache, object);
581 object = parent;
582 spin_lock(&object->lock);
583 dump_object_info(object);
584 spin_unlock(&object->lock);
585 goto out;
588 rb_link_node(&object->rb_node, rb_parent, link);
589 rb_insert_color(&object->rb_node, &object_tree_root);
591 list_add_tail_rcu(&object->object_list, &object_list);
592 out:
593 write_unlock_irqrestore(&kmemleak_lock, flags);
594 return object;
598 * Remove the metadata (struct kmemleak_object) for a memory block from the
599 * object_list and object_tree_root and decrement its use_count.
601 static void __delete_object(struct kmemleak_object *object)
603 unsigned long flags;
605 write_lock_irqsave(&kmemleak_lock, flags);
606 rb_erase(&object->rb_node, &object_tree_root);
607 list_del_rcu(&object->object_list);
608 write_unlock_irqrestore(&kmemleak_lock, flags);
610 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
611 WARN_ON(atomic_read(&object->use_count) < 2);
614 * Locking here also ensures that the corresponding memory block
615 * cannot be freed when it is being scanned.
617 spin_lock_irqsave(&object->lock, flags);
618 object->flags &= ~OBJECT_ALLOCATED;
619 spin_unlock_irqrestore(&object->lock, flags);
620 put_object(object);
624 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
625 * delete it.
627 static void delete_object_full(unsigned long ptr)
629 struct kmemleak_object *object;
631 object = find_and_get_object(ptr, 0);
632 if (!object) {
633 #ifdef DEBUG
634 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
635 ptr);
636 #endif
637 return;
639 __delete_object(object);
640 put_object(object);
644 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
645 * delete it. If the memory block is partially freed, the function may create
646 * additional metadata for the remaining parts of the block.
648 static void delete_object_part(unsigned long ptr, size_t size)
650 struct kmemleak_object *object;
651 unsigned long start, end;
653 object = find_and_get_object(ptr, 1);
654 if (!object) {
655 #ifdef DEBUG
656 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
657 "(size %zu)\n", ptr, size);
658 #endif
659 return;
661 __delete_object(object);
664 * Create one or two objects that may result from the memory block
665 * split. Note that partial freeing is only done by free_bootmem() and
666 * this happens before kmemleak_init() is called. The path below is
667 * only executed during early log recording in kmemleak_init(), so
668 * GFP_KERNEL is enough.
670 start = object->pointer;
671 end = object->pointer + object->size;
672 if (ptr > start)
673 create_object(start, ptr - start, object->min_count,
674 GFP_KERNEL);
675 if (ptr + size < end)
676 create_object(ptr + size, end - ptr - size, object->min_count,
677 GFP_KERNEL);
679 put_object(object);
682 static void __paint_it(struct kmemleak_object *object, int color)
684 object->min_count = color;
685 if (color == KMEMLEAK_BLACK)
686 object->flags |= OBJECT_NO_SCAN;
689 static void paint_it(struct kmemleak_object *object, int color)
691 unsigned long flags;
693 spin_lock_irqsave(&object->lock, flags);
694 __paint_it(object, color);
695 spin_unlock_irqrestore(&object->lock, flags);
698 static void paint_ptr(unsigned long ptr, int color)
700 struct kmemleak_object *object;
702 object = find_and_get_object(ptr, 0);
703 if (!object) {
704 kmemleak_warn("Trying to color unknown object "
705 "at 0x%08lx as %s\n", ptr,
706 (color == KMEMLEAK_GREY) ? "Grey" :
707 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
708 return;
710 paint_it(object, color);
711 put_object(object);
715 * Mark an object permanently as gray-colored so that it can no longer be
716 * reported as a leak. This is used in general to mark a false positive.
718 static void make_gray_object(unsigned long ptr)
720 paint_ptr(ptr, KMEMLEAK_GREY);
724 * Mark the object as black-colored so that it is ignored from scans and
725 * reporting.
727 static void make_black_object(unsigned long ptr)
729 paint_ptr(ptr, KMEMLEAK_BLACK);
733 * Add a scanning area to the object. If at least one such area is added,
734 * kmemleak will only scan these ranges rather than the whole memory block.
736 static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
738 unsigned long flags;
739 struct kmemleak_object *object;
740 struct kmemleak_scan_area *area;
742 object = find_and_get_object(ptr, 1);
743 if (!object) {
744 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
745 ptr);
746 return;
749 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
750 if (!area) {
751 pr_warning("Cannot allocate a scan area\n");
752 goto out;
755 spin_lock_irqsave(&object->lock, flags);
756 if (ptr + size > object->pointer + object->size) {
757 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
758 dump_object_info(object);
759 kmem_cache_free(scan_area_cache, area);
760 goto out_unlock;
763 INIT_HLIST_NODE(&area->node);
764 area->start = ptr;
765 area->size = size;
767 hlist_add_head(&area->node, &object->area_list);
768 out_unlock:
769 spin_unlock_irqrestore(&object->lock, flags);
770 out:
771 put_object(object);
775 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
776 * pointer. Such object will not be scanned by kmemleak but references to it
777 * are searched.
779 static void object_no_scan(unsigned long ptr)
781 unsigned long flags;
782 struct kmemleak_object *object;
784 object = find_and_get_object(ptr, 0);
785 if (!object) {
786 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
787 return;
790 spin_lock_irqsave(&object->lock, flags);
791 object->flags |= OBJECT_NO_SCAN;
792 spin_unlock_irqrestore(&object->lock, flags);
793 put_object(object);
797 * Log an early kmemleak_* call to the early_log buffer. These calls will be
798 * processed later once kmemleak is fully initialized.
800 static void __init log_early(int op_type, const void *ptr, size_t size,
801 int min_count)
803 unsigned long flags;
804 struct early_log *log;
806 if (atomic_read(&kmemleak_error)) {
807 /* kmemleak stopped recording, just count the requests */
808 crt_early_log++;
809 return;
812 if (crt_early_log >= ARRAY_SIZE(early_log)) {
813 kmemleak_disable();
814 return;
818 * There is no need for locking since the kernel is still in UP mode
819 * at this stage. Disabling the IRQs is enough.
821 local_irq_save(flags);
822 log = &early_log[crt_early_log];
823 log->op_type = op_type;
824 log->ptr = ptr;
825 log->size = size;
826 log->min_count = min_count;
827 log->trace_len = __save_stack_trace(log->trace);
828 crt_early_log++;
829 local_irq_restore(flags);
833 * Log an early allocated block and populate the stack trace.
835 static void early_alloc(struct early_log *log)
837 struct kmemleak_object *object;
838 unsigned long flags;
839 int i;
841 if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
842 return;
845 * RCU locking needed to ensure object is not freed via put_object().
847 rcu_read_lock();
848 object = create_object((unsigned long)log->ptr, log->size,
849 log->min_count, GFP_ATOMIC);
850 if (!object)
851 goto out;
852 spin_lock_irqsave(&object->lock, flags);
853 for (i = 0; i < log->trace_len; i++)
854 object->trace[i] = log->trace[i];
855 object->trace_len = log->trace_len;
856 spin_unlock_irqrestore(&object->lock, flags);
857 out:
858 rcu_read_unlock();
862 * Log an early allocated block and populate the stack trace.
864 static void early_alloc_percpu(struct early_log *log)
866 unsigned int cpu;
867 const void __percpu *ptr = log->ptr;
869 for_each_possible_cpu(cpu) {
870 log->ptr = per_cpu_ptr(ptr, cpu);
871 early_alloc(log);
876 * kmemleak_alloc - register a newly allocated object
877 * @ptr: pointer to beginning of the object
878 * @size: size of the object
879 * @min_count: minimum number of references to this object. If during memory
880 * scanning a number of references less than @min_count is found,
881 * the object is reported as a memory leak. If @min_count is 0,
882 * the object is never reported as a leak. If @min_count is -1,
883 * the object is ignored (not scanned and not reported as a leak)
884 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
886 * This function is called from the kernel allocators when a new object
887 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
889 void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
890 gfp_t gfp)
892 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
894 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
895 create_object((unsigned long)ptr, size, min_count, gfp);
896 else if (atomic_read(&kmemleak_early_log))
897 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
899 EXPORT_SYMBOL_GPL(kmemleak_alloc);
902 * kmemleak_alloc_percpu - register a newly allocated __percpu object
903 * @ptr: __percpu pointer to beginning of the object
904 * @size: size of the object
906 * This function is called from the kernel percpu allocator when a new object
907 * (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL
908 * allocation.
910 void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size)
912 unsigned int cpu;
914 pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
917 * Percpu allocations are only scanned and not reported as leaks
918 * (min_count is set to 0).
920 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
921 for_each_possible_cpu(cpu)
922 create_object((unsigned long)per_cpu_ptr(ptr, cpu),
923 size, 0, GFP_KERNEL);
924 else if (atomic_read(&kmemleak_early_log))
925 log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
927 EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
930 * kmemleak_free - unregister a previously registered object
931 * @ptr: pointer to beginning of the object
933 * This function is called from the kernel allocators when an object (memory
934 * block) is freed (kmem_cache_free, kfree, vfree etc.).
936 void __ref kmemleak_free(const void *ptr)
938 pr_debug("%s(0x%p)\n", __func__, ptr);
940 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
941 delete_object_full((unsigned long)ptr);
942 else if (atomic_read(&kmemleak_early_log))
943 log_early(KMEMLEAK_FREE, ptr, 0, 0);
945 EXPORT_SYMBOL_GPL(kmemleak_free);
948 * kmemleak_free_part - partially unregister a previously registered object
949 * @ptr: pointer to the beginning or inside the object. This also
950 * represents the start of the range to be freed
951 * @size: size to be unregistered
953 * This function is called when only a part of a memory block is freed
954 * (usually from the bootmem allocator).
956 void __ref kmemleak_free_part(const void *ptr, size_t size)
958 pr_debug("%s(0x%p)\n", __func__, ptr);
960 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
961 delete_object_part((unsigned long)ptr, size);
962 else if (atomic_read(&kmemleak_early_log))
963 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
965 EXPORT_SYMBOL_GPL(kmemleak_free_part);
968 * kmemleak_free_percpu - unregister a previously registered __percpu object
969 * @ptr: __percpu pointer to beginning of the object
971 * This function is called from the kernel percpu allocator when an object
972 * (memory block) is freed (free_percpu).
974 void __ref kmemleak_free_percpu(const void __percpu *ptr)
976 unsigned int cpu;
978 pr_debug("%s(0x%p)\n", __func__, ptr);
980 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
981 for_each_possible_cpu(cpu)
982 delete_object_full((unsigned long)per_cpu_ptr(ptr,
983 cpu));
984 else if (atomic_read(&kmemleak_early_log))
985 log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
987 EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
990 * kmemleak_not_leak - mark an allocated object as false positive
991 * @ptr: pointer to beginning of the object
993 * Calling this function on an object will cause the memory block to no longer
994 * be reported as leak and always be scanned.
996 void __ref kmemleak_not_leak(const void *ptr)
998 pr_debug("%s(0x%p)\n", __func__, ptr);
1000 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
1001 make_gray_object((unsigned long)ptr);
1002 else if (atomic_read(&kmemleak_early_log))
1003 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
1005 EXPORT_SYMBOL(kmemleak_not_leak);
1008 * kmemleak_ignore - ignore an allocated object
1009 * @ptr: pointer to beginning of the object
1011 * Calling this function on an object will cause the memory block to be
1012 * ignored (not scanned and not reported as a leak). This is usually done when
1013 * it is known that the corresponding block is not a leak and does not contain
1014 * any references to other allocated memory blocks.
1016 void __ref kmemleak_ignore(const void *ptr)
1018 pr_debug("%s(0x%p)\n", __func__, ptr);
1020 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
1021 make_black_object((unsigned long)ptr);
1022 else if (atomic_read(&kmemleak_early_log))
1023 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
1025 EXPORT_SYMBOL(kmemleak_ignore);
1028 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1029 * @ptr: pointer to beginning or inside the object. This also
1030 * represents the start of the scan area
1031 * @size: size of the scan area
1032 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1034 * This function is used when it is known that only certain parts of an object
1035 * contain references to other objects. Kmemleak will only scan these areas
1036 * reducing the number false negatives.
1038 void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
1040 pr_debug("%s(0x%p)\n", __func__, ptr);
1042 if (atomic_read(&kmemleak_enabled) && ptr && size && !IS_ERR(ptr))
1043 add_scan_area((unsigned long)ptr, size, gfp);
1044 else if (atomic_read(&kmemleak_early_log))
1045 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
1047 EXPORT_SYMBOL(kmemleak_scan_area);
1050 * kmemleak_no_scan - do not scan an allocated object
1051 * @ptr: pointer to beginning of the object
1053 * This function notifies kmemleak not to scan the given memory block. Useful
1054 * in situations where it is known that the given object does not contain any
1055 * references to other objects. Kmemleak will not scan such objects reducing
1056 * the number of false negatives.
1058 void __ref kmemleak_no_scan(const void *ptr)
1060 pr_debug("%s(0x%p)\n", __func__, ptr);
1062 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
1063 object_no_scan((unsigned long)ptr);
1064 else if (atomic_read(&kmemleak_early_log))
1065 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
1067 EXPORT_SYMBOL(kmemleak_no_scan);
1070 * Update an object's checksum and return true if it was modified.
1072 static bool update_checksum(struct kmemleak_object *object)
1074 u32 old_csum = object->checksum;
1076 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
1077 return false;
1079 object->checksum = crc32(0, (void *)object->pointer, object->size);
1080 return object->checksum != old_csum;
1084 * Memory scanning is a long process and it needs to be interruptable. This
1085 * function checks whether such interrupt condition occurred.
1087 static int scan_should_stop(void)
1089 if (!atomic_read(&kmemleak_enabled))
1090 return 1;
1093 * This function may be called from either process or kthread context,
1094 * hence the need to check for both stop conditions.
1096 if (current->mm)
1097 return signal_pending(current);
1098 else
1099 return kthread_should_stop();
1101 return 0;
1105 * Scan a memory block (exclusive range) for valid pointers and add those
1106 * found to the gray list.
1108 static void scan_block(void *_start, void *_end,
1109 struct kmemleak_object *scanned, int allow_resched)
1111 unsigned long *ptr;
1112 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1113 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1115 for (ptr = start; ptr < end; ptr++) {
1116 struct kmemleak_object *object;
1117 unsigned long flags;
1118 unsigned long pointer;
1120 if (allow_resched)
1121 cond_resched();
1122 if (scan_should_stop())
1123 break;
1125 /* don't scan uninitialized memory */
1126 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1127 BYTES_PER_POINTER))
1128 continue;
1130 pointer = *ptr;
1132 object = find_and_get_object(pointer, 1);
1133 if (!object)
1134 continue;
1135 if (object == scanned) {
1136 /* self referenced, ignore */
1137 put_object(object);
1138 continue;
1142 * Avoid the lockdep recursive warning on object->lock being
1143 * previously acquired in scan_object(). These locks are
1144 * enclosed by scan_mutex.
1146 spin_lock_irqsave_nested(&object->lock, flags,
1147 SINGLE_DEPTH_NESTING);
1148 if (!color_white(object)) {
1149 /* non-orphan, ignored or new */
1150 spin_unlock_irqrestore(&object->lock, flags);
1151 put_object(object);
1152 continue;
1156 * Increase the object's reference count (number of pointers
1157 * to the memory block). If this count reaches the required
1158 * minimum, the object's color will become gray and it will be
1159 * added to the gray_list.
1161 object->count++;
1162 if (color_gray(object)) {
1163 list_add_tail(&object->gray_list, &gray_list);
1164 spin_unlock_irqrestore(&object->lock, flags);
1165 continue;
1168 spin_unlock_irqrestore(&object->lock, flags);
1169 put_object(object);
1174 * Scan a memory block corresponding to a kmemleak_object. A condition is
1175 * that object->use_count >= 1.
1177 static void scan_object(struct kmemleak_object *object)
1179 struct kmemleak_scan_area *area;
1180 unsigned long flags;
1183 * Once the object->lock is acquired, the corresponding memory block
1184 * cannot be freed (the same lock is acquired in delete_object).
1186 spin_lock_irqsave(&object->lock, flags);
1187 if (object->flags & OBJECT_NO_SCAN)
1188 goto out;
1189 if (!(object->flags & OBJECT_ALLOCATED))
1190 /* already freed object */
1191 goto out;
1192 if (hlist_empty(&object->area_list)) {
1193 void *start = (void *)object->pointer;
1194 void *end = (void *)(object->pointer + object->size);
1196 while (start < end && (object->flags & OBJECT_ALLOCATED) &&
1197 !(object->flags & OBJECT_NO_SCAN)) {
1198 scan_block(start, min(start + MAX_SCAN_SIZE, end),
1199 object, 0);
1200 start += MAX_SCAN_SIZE;
1202 spin_unlock_irqrestore(&object->lock, flags);
1203 cond_resched();
1204 spin_lock_irqsave(&object->lock, flags);
1206 } else
1207 hlist_for_each_entry(area, &object->area_list, node)
1208 scan_block((void *)area->start,
1209 (void *)(area->start + area->size),
1210 object, 0);
1211 out:
1212 spin_unlock_irqrestore(&object->lock, flags);
1216 * Scan the objects already referenced (gray objects). More objects will be
1217 * referenced and, if there are no memory leaks, all the objects are scanned.
1219 static void scan_gray_list(void)
1221 struct kmemleak_object *object, *tmp;
1224 * The list traversal is safe for both tail additions and removals
1225 * from inside the loop. The kmemleak objects cannot be freed from
1226 * outside the loop because their use_count was incremented.
1228 object = list_entry(gray_list.next, typeof(*object), gray_list);
1229 while (&object->gray_list != &gray_list) {
1230 cond_resched();
1232 /* may add new objects to the list */
1233 if (!scan_should_stop())
1234 scan_object(object);
1236 tmp = list_entry(object->gray_list.next, typeof(*object),
1237 gray_list);
1239 /* remove the object from the list and release it */
1240 list_del(&object->gray_list);
1241 put_object(object);
1243 object = tmp;
1245 WARN_ON(!list_empty(&gray_list));
1249 * Scan data sections and all the referenced memory blocks allocated via the
1250 * kernel's standard allocators. This function must be called with the
1251 * scan_mutex held.
1253 static void kmemleak_scan(void)
1255 unsigned long flags;
1256 struct kmemleak_object *object;
1257 int i;
1258 int new_leaks = 0;
1260 jiffies_last_scan = jiffies;
1262 /* prepare the kmemleak_object's */
1263 rcu_read_lock();
1264 list_for_each_entry_rcu(object, &object_list, object_list) {
1265 spin_lock_irqsave(&object->lock, flags);
1266 #ifdef DEBUG
1268 * With a few exceptions there should be a maximum of
1269 * 1 reference to any object at this point.
1271 if (atomic_read(&object->use_count) > 1) {
1272 pr_debug("object->use_count = %d\n",
1273 atomic_read(&object->use_count));
1274 dump_object_info(object);
1276 #endif
1277 /* reset the reference count (whiten the object) */
1278 object->count = 0;
1279 if (color_gray(object) && get_object(object))
1280 list_add_tail(&object->gray_list, &gray_list);
1282 spin_unlock_irqrestore(&object->lock, flags);
1284 rcu_read_unlock();
1286 /* data/bss scanning */
1287 scan_block(_sdata, _edata, NULL, 1);
1288 scan_block(__bss_start, __bss_stop, NULL, 1);
1290 #ifdef CONFIG_SMP
1291 /* per-cpu sections scanning */
1292 for_each_possible_cpu(i)
1293 scan_block(__per_cpu_start + per_cpu_offset(i),
1294 __per_cpu_end + per_cpu_offset(i), NULL, 1);
1295 #endif
1298 * Struct page scanning for each node.
1300 lock_memory_hotplug();
1301 for_each_online_node(i) {
1302 unsigned long start_pfn = node_start_pfn(i);
1303 unsigned long end_pfn = node_end_pfn(i);
1304 unsigned long pfn;
1306 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1307 struct page *page;
1309 if (!pfn_valid(pfn))
1310 continue;
1311 page = pfn_to_page(pfn);
1312 /* only scan if page is in use */
1313 if (page_count(page) == 0)
1314 continue;
1315 scan_block(page, page + 1, NULL, 1);
1318 unlock_memory_hotplug();
1321 * Scanning the task stacks (may introduce false negatives).
1323 if (kmemleak_stack_scan) {
1324 struct task_struct *p, *g;
1326 read_lock(&tasklist_lock);
1327 do_each_thread(g, p) {
1328 scan_block(task_stack_page(p), task_stack_page(p) +
1329 THREAD_SIZE, NULL, 0);
1330 } while_each_thread(g, p);
1331 read_unlock(&tasklist_lock);
1335 * Scan the objects already referenced from the sections scanned
1336 * above.
1338 scan_gray_list();
1341 * Check for new or unreferenced objects modified since the previous
1342 * scan and color them gray until the next scan.
1344 rcu_read_lock();
1345 list_for_each_entry_rcu(object, &object_list, object_list) {
1346 spin_lock_irqsave(&object->lock, flags);
1347 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1348 && update_checksum(object) && get_object(object)) {
1349 /* color it gray temporarily */
1350 object->count = object->min_count;
1351 list_add_tail(&object->gray_list, &gray_list);
1353 spin_unlock_irqrestore(&object->lock, flags);
1355 rcu_read_unlock();
1358 * Re-scan the gray list for modified unreferenced objects.
1360 scan_gray_list();
1363 * If scanning was stopped do not report any new unreferenced objects.
1365 if (scan_should_stop())
1366 return;
1369 * Scanning result reporting.
1371 rcu_read_lock();
1372 list_for_each_entry_rcu(object, &object_list, object_list) {
1373 spin_lock_irqsave(&object->lock, flags);
1374 if (unreferenced_object(object) &&
1375 !(object->flags & OBJECT_REPORTED)) {
1376 object->flags |= OBJECT_REPORTED;
1377 new_leaks++;
1379 spin_unlock_irqrestore(&object->lock, flags);
1381 rcu_read_unlock();
1383 if (new_leaks)
1384 pr_info("%d new suspected memory leaks (see "
1385 "/sys/kernel/debug/kmemleak)\n", new_leaks);
1390 * Thread function performing automatic memory scanning. Unreferenced objects
1391 * at the end of a memory scan are reported but only the first time.
1393 static int kmemleak_scan_thread(void *arg)
1395 static int first_run = 1;
1397 pr_info("Automatic memory scanning thread started\n");
1398 set_user_nice(current, 10);
1401 * Wait before the first scan to allow the system to fully initialize.
1403 if (first_run) {
1404 first_run = 0;
1405 ssleep(SECS_FIRST_SCAN);
1408 while (!kthread_should_stop()) {
1409 signed long timeout = jiffies_scan_wait;
1411 mutex_lock(&scan_mutex);
1412 kmemleak_scan();
1413 mutex_unlock(&scan_mutex);
1415 /* wait before the next scan */
1416 while (timeout && !kthread_should_stop())
1417 timeout = schedule_timeout_interruptible(timeout);
1420 pr_info("Automatic memory scanning thread ended\n");
1422 return 0;
1426 * Start the automatic memory scanning thread. This function must be called
1427 * with the scan_mutex held.
1429 static void start_scan_thread(void)
1431 if (scan_thread)
1432 return;
1433 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1434 if (IS_ERR(scan_thread)) {
1435 pr_warning("Failed to create the scan thread\n");
1436 scan_thread = NULL;
1441 * Stop the automatic memory scanning thread. This function must be called
1442 * with the scan_mutex held.
1444 static void stop_scan_thread(void)
1446 if (scan_thread) {
1447 kthread_stop(scan_thread);
1448 scan_thread = NULL;
1453 * Iterate over the object_list and return the first valid object at or after
1454 * the required position with its use_count incremented. The function triggers
1455 * a memory scanning when the pos argument points to the first position.
1457 static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1459 struct kmemleak_object *object;
1460 loff_t n = *pos;
1461 int err;
1463 err = mutex_lock_interruptible(&scan_mutex);
1464 if (err < 0)
1465 return ERR_PTR(err);
1467 rcu_read_lock();
1468 list_for_each_entry_rcu(object, &object_list, object_list) {
1469 if (n-- > 0)
1470 continue;
1471 if (get_object(object))
1472 goto out;
1474 object = NULL;
1475 out:
1476 return object;
1480 * Return the next object in the object_list. The function decrements the
1481 * use_count of the previous object and increases that of the next one.
1483 static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1485 struct kmemleak_object *prev_obj = v;
1486 struct kmemleak_object *next_obj = NULL;
1487 struct kmemleak_object *obj = prev_obj;
1489 ++(*pos);
1491 list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
1492 if (get_object(obj)) {
1493 next_obj = obj;
1494 break;
1498 put_object(prev_obj);
1499 return next_obj;
1503 * Decrement the use_count of the last object required, if any.
1505 static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1507 if (!IS_ERR(v)) {
1509 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1510 * waiting was interrupted, so only release it if !IS_ERR.
1512 rcu_read_unlock();
1513 mutex_unlock(&scan_mutex);
1514 if (v)
1515 put_object(v);
1520 * Print the information for an unreferenced object to the seq file.
1522 static int kmemleak_seq_show(struct seq_file *seq, void *v)
1524 struct kmemleak_object *object = v;
1525 unsigned long flags;
1527 spin_lock_irqsave(&object->lock, flags);
1528 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
1529 print_unreferenced(seq, object);
1530 spin_unlock_irqrestore(&object->lock, flags);
1531 return 0;
1534 static const struct seq_operations kmemleak_seq_ops = {
1535 .start = kmemleak_seq_start,
1536 .next = kmemleak_seq_next,
1537 .stop = kmemleak_seq_stop,
1538 .show = kmemleak_seq_show,
1541 static int kmemleak_open(struct inode *inode, struct file *file)
1543 return seq_open(file, &kmemleak_seq_ops);
1546 static int kmemleak_release(struct inode *inode, struct file *file)
1548 return seq_release(inode, file);
1551 static int dump_str_object_info(const char *str)
1553 unsigned long flags;
1554 struct kmemleak_object *object;
1555 unsigned long addr;
1557 if (kstrtoul(str, 0, &addr))
1558 return -EINVAL;
1559 object = find_and_get_object(addr, 0);
1560 if (!object) {
1561 pr_info("Unknown object at 0x%08lx\n", addr);
1562 return -EINVAL;
1565 spin_lock_irqsave(&object->lock, flags);
1566 dump_object_info(object);
1567 spin_unlock_irqrestore(&object->lock, flags);
1569 put_object(object);
1570 return 0;
1574 * We use grey instead of black to ensure we can do future scans on the same
1575 * objects. If we did not do future scans these black objects could
1576 * potentially contain references to newly allocated objects in the future and
1577 * we'd end up with false positives.
1579 static void kmemleak_clear(void)
1581 struct kmemleak_object *object;
1582 unsigned long flags;
1584 rcu_read_lock();
1585 list_for_each_entry_rcu(object, &object_list, object_list) {
1586 spin_lock_irqsave(&object->lock, flags);
1587 if ((object->flags & OBJECT_REPORTED) &&
1588 unreferenced_object(object))
1589 __paint_it(object, KMEMLEAK_GREY);
1590 spin_unlock_irqrestore(&object->lock, flags);
1592 rcu_read_unlock();
1596 * File write operation to configure kmemleak at run-time. The following
1597 * commands can be written to the /sys/kernel/debug/kmemleak file:
1598 * off - disable kmemleak (irreversible)
1599 * stack=on - enable the task stacks scanning
1600 * stack=off - disable the tasks stacks scanning
1601 * scan=on - start the automatic memory scanning thread
1602 * scan=off - stop the automatic memory scanning thread
1603 * scan=... - set the automatic memory scanning period in seconds (0 to
1604 * disable it)
1605 * scan - trigger a memory scan
1606 * clear - mark all current reported unreferenced kmemleak objects as
1607 * grey to ignore printing them
1608 * dump=... - dump information about the object found at the given address
1610 static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1611 size_t size, loff_t *ppos)
1613 char buf[64];
1614 int buf_size;
1615 int ret;
1617 if (!atomic_read(&kmemleak_enabled))
1618 return -EBUSY;
1620 buf_size = min(size, (sizeof(buf) - 1));
1621 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1622 return -EFAULT;
1623 buf[buf_size] = 0;
1625 ret = mutex_lock_interruptible(&scan_mutex);
1626 if (ret < 0)
1627 return ret;
1629 if (strncmp(buf, "off", 3) == 0)
1630 kmemleak_disable();
1631 else if (strncmp(buf, "stack=on", 8) == 0)
1632 kmemleak_stack_scan = 1;
1633 else if (strncmp(buf, "stack=off", 9) == 0)
1634 kmemleak_stack_scan = 0;
1635 else if (strncmp(buf, "scan=on", 7) == 0)
1636 start_scan_thread();
1637 else if (strncmp(buf, "scan=off", 8) == 0)
1638 stop_scan_thread();
1639 else if (strncmp(buf, "scan=", 5) == 0) {
1640 unsigned long secs;
1642 ret = strict_strtoul(buf + 5, 0, &secs);
1643 if (ret < 0)
1644 goto out;
1645 stop_scan_thread();
1646 if (secs) {
1647 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1648 start_scan_thread();
1650 } else if (strncmp(buf, "scan", 4) == 0)
1651 kmemleak_scan();
1652 else if (strncmp(buf, "clear", 5) == 0)
1653 kmemleak_clear();
1654 else if (strncmp(buf, "dump=", 5) == 0)
1655 ret = dump_str_object_info(buf + 5);
1656 else
1657 ret = -EINVAL;
1659 out:
1660 mutex_unlock(&scan_mutex);
1661 if (ret < 0)
1662 return ret;
1664 /* ignore the rest of the buffer, only one command at a time */
1665 *ppos += size;
1666 return size;
1669 static const struct file_operations kmemleak_fops = {
1670 .owner = THIS_MODULE,
1671 .open = kmemleak_open,
1672 .read = seq_read,
1673 .write = kmemleak_write,
1674 .llseek = seq_lseek,
1675 .release = kmemleak_release,
1679 * Stop the memory scanning thread and free the kmemleak internal objects if
1680 * no previous scan thread (otherwise, kmemleak may still have some useful
1681 * information on memory leaks).
1683 static void kmemleak_do_cleanup(struct work_struct *work)
1685 struct kmemleak_object *object;
1686 bool cleanup = scan_thread == NULL;
1688 mutex_lock(&scan_mutex);
1689 stop_scan_thread();
1691 if (cleanup) {
1692 rcu_read_lock();
1693 list_for_each_entry_rcu(object, &object_list, object_list)
1694 delete_object_full(object->pointer);
1695 rcu_read_unlock();
1697 mutex_unlock(&scan_mutex);
1700 static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
1703 * Disable kmemleak. No memory allocation/freeing will be traced once this
1704 * function is called. Disabling kmemleak is an irreversible operation.
1706 static void kmemleak_disable(void)
1708 /* atomically check whether it was already invoked */
1709 if (atomic_cmpxchg(&kmemleak_error, 0, 1))
1710 return;
1712 /* stop any memory operation tracing */
1713 atomic_set(&kmemleak_enabled, 0);
1715 /* check whether it is too early for a kernel thread */
1716 if (atomic_read(&kmemleak_initialized))
1717 schedule_work(&cleanup_work);
1719 pr_info("Kernel memory leak detector disabled\n");
1723 * Allow boot-time kmemleak disabling (enabled by default).
1725 static int kmemleak_boot_config(char *str)
1727 if (!str)
1728 return -EINVAL;
1729 if (strcmp(str, "off") == 0)
1730 kmemleak_disable();
1731 else if (strcmp(str, "on") == 0)
1732 kmemleak_skip_disable = 1;
1733 else
1734 return -EINVAL;
1735 return 0;
1737 early_param("kmemleak", kmemleak_boot_config);
1739 static void __init print_log_trace(struct early_log *log)
1741 struct stack_trace trace;
1743 trace.nr_entries = log->trace_len;
1744 trace.entries = log->trace;
1746 pr_notice("Early log backtrace:\n");
1747 print_stack_trace(&trace, 2);
1751 * Kmemleak initialization.
1753 void __init kmemleak_init(void)
1755 int i;
1756 unsigned long flags;
1758 #ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1759 if (!kmemleak_skip_disable) {
1760 atomic_set(&kmemleak_early_log, 0);
1761 kmemleak_disable();
1762 return;
1764 #endif
1766 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1767 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1769 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1770 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1772 if (crt_early_log >= ARRAY_SIZE(early_log))
1773 pr_warning("Early log buffer exceeded (%d), please increase "
1774 "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log);
1776 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1777 local_irq_save(flags);
1778 atomic_set(&kmemleak_early_log, 0);
1779 if (atomic_read(&kmemleak_error)) {
1780 local_irq_restore(flags);
1781 return;
1782 } else
1783 atomic_set(&kmemleak_enabled, 1);
1784 local_irq_restore(flags);
1787 * This is the point where tracking allocations is safe. Automatic
1788 * scanning is started during the late initcall. Add the early logged
1789 * callbacks to the kmemleak infrastructure.
1791 for (i = 0; i < crt_early_log; i++) {
1792 struct early_log *log = &early_log[i];
1794 switch (log->op_type) {
1795 case KMEMLEAK_ALLOC:
1796 early_alloc(log);
1797 break;
1798 case KMEMLEAK_ALLOC_PERCPU:
1799 early_alloc_percpu(log);
1800 break;
1801 case KMEMLEAK_FREE:
1802 kmemleak_free(log->ptr);
1803 break;
1804 case KMEMLEAK_FREE_PART:
1805 kmemleak_free_part(log->ptr, log->size);
1806 break;
1807 case KMEMLEAK_FREE_PERCPU:
1808 kmemleak_free_percpu(log->ptr);
1809 break;
1810 case KMEMLEAK_NOT_LEAK:
1811 kmemleak_not_leak(log->ptr);
1812 break;
1813 case KMEMLEAK_IGNORE:
1814 kmemleak_ignore(log->ptr);
1815 break;
1816 case KMEMLEAK_SCAN_AREA:
1817 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
1818 break;
1819 case KMEMLEAK_NO_SCAN:
1820 kmemleak_no_scan(log->ptr);
1821 break;
1822 default:
1823 kmemleak_warn("Unknown early log operation: %d\n",
1824 log->op_type);
1827 if (atomic_read(&kmemleak_warning)) {
1828 print_log_trace(log);
1829 atomic_set(&kmemleak_warning, 0);
1835 * Late initialization function.
1837 static int __init kmemleak_late_init(void)
1839 struct dentry *dentry;
1841 atomic_set(&kmemleak_initialized, 1);
1843 if (atomic_read(&kmemleak_error)) {
1845 * Some error occurred and kmemleak was disabled. There is a
1846 * small chance that kmemleak_disable() was called immediately
1847 * after setting kmemleak_initialized and we may end up with
1848 * two clean-up threads but serialized by scan_mutex.
1850 schedule_work(&cleanup_work);
1851 return -ENOMEM;
1854 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1855 &kmemleak_fops);
1856 if (!dentry)
1857 pr_warning("Failed to create the debugfs kmemleak file\n");
1858 mutex_lock(&scan_mutex);
1859 start_scan_thread();
1860 mutex_unlock(&scan_mutex);
1862 pr_info("Kernel memory leak detector initialized\n");
1864 return 0;
1866 late_initcall(kmemleak_late_init);