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Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001/*
2 * mm/kmemleak.c
3 *
4 * Copyright (C) 2008 ARM Limited
5 * Written by Catalin Marinas <catalin.marinas@arm.com>
6 *
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.
10 *
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.
15 *
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
19 *
20 *
21 * For more information on the algorithm and kmemleak usage, please see
22 * Documentation/kmemleak.txt.
23 *
24 * Notes on locking
25 * ----------------
26 *
27 * The following locks and mutexes are used by kmemleak:
28 *
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 priority search 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
Catalin Marinas4698c1f2009-06-26 17:38:27 +010051 * 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
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010055 *
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.
62 */
63
Joe Perchesae281062009-06-23 14:40:26 +010064#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
65
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010066#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/module.h>
73#include <linux/kthread.h>
74#include <linux/prio_tree.h>
75#include <linux/gfp.h>
76#include <linux/fs.h>
77#include <linux/debugfs.h>
78#include <linux/seq_file.h>
79#include <linux/cpumask.h>
80#include <linux/spinlock.h>
81#include <linux/mutex.h>
82#include <linux/rcupdate.h>
83#include <linux/stacktrace.h>
84#include <linux/cache.h>
85#include <linux/percpu.h>
86#include <linux/hardirq.h>
87#include <linux/mmzone.h>
88#include <linux/slab.h>
89#include <linux/thread_info.h>
90#include <linux/err.h>
91#include <linux/uaccess.h>
92#include <linux/string.h>
93#include <linux/nodemask.h>
94#include <linux/mm.h>
95
96#include <asm/sections.h>
97#include <asm/processor.h>
98#include <asm/atomic.h>
99
Pekka Enberg8e019362009-08-27 14:50:00 +0100100#include <linux/kmemcheck.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100101#include <linux/kmemleak.h>
102
103/*
104 * Kmemleak configuration and common defines.
105 */
106#define MAX_TRACE 16 /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100107#define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100108#define SECS_FIRST_SCAN 60 /* delay before the first scan */
109#define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
Catalin Marinas25873622009-07-07 10:32:58 +0100110#define GRAY_LIST_PASSES 25 /* maximum number of gray list scans */
Catalin Marinasaf986032009-08-27 14:29:12 +0100111#define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100112
113#define BYTES_PER_POINTER sizeof(void *)
114
Catalin Marinas216c04b2009-06-17 18:29:02 +0100115/* GFP bitmask for kmemleak internal allocations */
116#define GFP_KMEMLEAK_MASK (GFP_KERNEL | GFP_ATOMIC)
117
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100118/* scanning area inside a memory block */
119struct kmemleak_scan_area {
120 struct hlist_node node;
121 unsigned long offset;
122 size_t length;
123};
124
125/*
126 * Structure holding the metadata for each allocated memory block.
127 * Modifications to such objects should be made while holding the
128 * object->lock. Insertions or deletions from object_list, gray_list or
129 * tree_node are already protected by the corresponding locks or mutex (see
130 * the notes on locking above). These objects are reference-counted
131 * (use_count) and freed using the RCU mechanism.
132 */
133struct kmemleak_object {
134 spinlock_t lock;
135 unsigned long flags; /* object status flags */
136 struct list_head object_list;
137 struct list_head gray_list;
138 struct prio_tree_node tree_node;
139 struct rcu_head rcu; /* object_list lockless traversal */
140 /* object usage count; object freed when use_count == 0 */
141 atomic_t use_count;
142 unsigned long pointer;
143 size_t size;
144 /* minimum number of a pointers found before it is considered leak */
145 int min_count;
146 /* the total number of pointers found pointing to this object */
147 int count;
148 /* memory ranges to be scanned inside an object (empty for all) */
149 struct hlist_head area_list;
150 unsigned long trace[MAX_TRACE];
151 unsigned int trace_len;
152 unsigned long jiffies; /* creation timestamp */
153 pid_t pid; /* pid of the current task */
154 char comm[TASK_COMM_LEN]; /* executable name */
155};
156
157/* flag representing the memory block allocation status */
158#define OBJECT_ALLOCATED (1 << 0)
159/* flag set after the first reporting of an unreference object */
160#define OBJECT_REPORTED (1 << 1)
161/* flag set to not scan the object */
162#define OBJECT_NO_SCAN (1 << 2)
Catalin Marinas25873622009-07-07 10:32:58 +0100163/* flag set on newly allocated objects */
164#define OBJECT_NEW (1 << 3)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100165
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100166/* number of bytes to print per line; must be 16 or 32 */
167#define HEX_ROW_SIZE 16
168/* number of bytes to print at a time (1, 2, 4, 8) */
169#define HEX_GROUP_SIZE 1
170/* include ASCII after the hex output */
171#define HEX_ASCII 1
172/* max number of lines to be printed */
173#define HEX_MAX_LINES 2
174
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100175/* the list of all allocated objects */
176static LIST_HEAD(object_list);
177/* the list of gray-colored objects (see color_gray comment below) */
178static LIST_HEAD(gray_list);
179/* prio search tree for object boundaries */
180static struct prio_tree_root object_tree_root;
181/* rw_lock protecting the access to object_list and prio_tree_root */
182static DEFINE_RWLOCK(kmemleak_lock);
183
184/* allocation caches for kmemleak internal data */
185static struct kmem_cache *object_cache;
186static struct kmem_cache *scan_area_cache;
187
188/* set if tracing memory operations is enabled */
189static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
190/* set in the late_initcall if there were no errors */
191static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
192/* enables or disables early logging of the memory operations */
193static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
194/* set if a fata kmemleak error has occurred */
195static atomic_t kmemleak_error = ATOMIC_INIT(0);
196
197/* minimum and maximum address that may be valid pointers */
198static unsigned long min_addr = ULONG_MAX;
199static unsigned long max_addr;
200
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100201static struct task_struct *scan_thread;
Catalin Marinasacf49682009-06-26 17:38:29 +0100202/* used to avoid reporting of recently allocated objects */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100203static unsigned long jiffies_min_age;
Catalin Marinasacf49682009-06-26 17:38:29 +0100204static unsigned long jiffies_last_scan;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100205/* delay between automatic memory scannings */
206static signed long jiffies_scan_wait;
207/* enables or disables the task stacks scanning */
Catalin Marinase0a2a162009-06-26 17:38:25 +0100208static int kmemleak_stack_scan = 1;
Catalin Marinas4698c1f2009-06-26 17:38:27 +0100209/* protects the memory scanning, parameters and debug/kmemleak file access */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100210static DEFINE_MUTEX(scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100211
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100212/*
Catalin Marinas20301172009-06-17 18:29:04 +0100213 * Early object allocation/freeing logging. Kmemleak is initialized after the
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100214 * kernel allocator. However, both the kernel allocator and kmemleak may
Catalin Marinas20301172009-06-17 18:29:04 +0100215 * allocate memory blocks which need to be tracked. Kmemleak defines an
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100216 * arbitrary buffer to hold the allocation/freeing information before it is
217 * fully initialized.
218 */
219
220/* kmemleak operation type for early logging */
221enum {
222 KMEMLEAK_ALLOC,
223 KMEMLEAK_FREE,
Catalin Marinas53238a62009-07-07 10:33:00 +0100224 KMEMLEAK_FREE_PART,
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100225 KMEMLEAK_NOT_LEAK,
226 KMEMLEAK_IGNORE,
227 KMEMLEAK_SCAN_AREA,
228 KMEMLEAK_NO_SCAN
229};
230
231/*
232 * Structure holding the information passed to kmemleak callbacks during the
233 * early logging.
234 */
235struct early_log {
236 int op_type; /* kmemleak operation type */
237 const void *ptr; /* allocated/freed memory block */
238 size_t size; /* memory block size */
239 int min_count; /* minimum reference count */
240 unsigned long offset; /* scan area offset */
241 size_t length; /* scan area length */
Catalin Marinasfd678962009-08-27 14:29:17 +0100242 unsigned long trace[MAX_TRACE]; /* stack trace */
243 unsigned int trace_len; /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100244};
245
246/* early logging buffer and current position */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100247static struct early_log
248 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
249static int crt_early_log __initdata;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100250
251static void kmemleak_disable(void);
252
253/*
254 * Print a warning and dump the stack trace.
255 */
256#define kmemleak_warn(x...) do { \
257 pr_warning(x); \
258 dump_stack(); \
259} while (0)
260
261/*
262 * Macro invoked when a serious kmemleak condition occured and cannot be
Catalin Marinas20301172009-06-17 18:29:04 +0100263 * recovered from. Kmemleak will be disabled and further allocation/freeing
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100264 * tracing no longer available.
265 */
Catalin Marinas000814f2009-06-17 18:29:03 +0100266#define kmemleak_stop(x...) do { \
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100267 kmemleak_warn(x); \
268 kmemleak_disable(); \
269} while (0)
270
271/*
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100272 * Printing of the objects hex dump to the seq file. The number of lines to be
273 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
274 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
275 * with the object->lock held.
276 */
277static void hex_dump_object(struct seq_file *seq,
278 struct kmemleak_object *object)
279{
280 const u8 *ptr = (const u8 *)object->pointer;
281 int i, len, remaining;
282 unsigned char linebuf[HEX_ROW_SIZE * 5];
283
284 /* limit the number of lines to HEX_MAX_LINES */
285 remaining = len =
286 min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
287
288 seq_printf(seq, " hex dump (first %d bytes):\n", len);
289 for (i = 0; i < len; i += HEX_ROW_SIZE) {
290 int linelen = min(remaining, HEX_ROW_SIZE);
291
292 remaining -= HEX_ROW_SIZE;
293 hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
294 HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
295 HEX_ASCII);
296 seq_printf(seq, " %s\n", linebuf);
297 }
298}
299
300/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100301 * Object colors, encoded with count and min_count:
302 * - white - orphan object, not enough references to it (count < min_count)
303 * - gray - not orphan, not marked as false positive (min_count == 0) or
304 * sufficient references to it (count >= min_count)
305 * - black - ignore, it doesn't contain references (e.g. text section)
306 * (min_count == -1). No function defined for this color.
307 * Newly created objects don't have any color assigned (object->count == -1)
308 * before the next memory scan when they become white.
309 */
310static int color_white(const struct kmemleak_object *object)
311{
312 return object->count != -1 && object->count < object->min_count;
313}
314
315static int color_gray(const struct kmemleak_object *object)
316{
317 return object->min_count != -1 && object->count >= object->min_count;
318}
319
Catalin Marinas25873622009-07-07 10:32:58 +0100320static int color_black(const struct kmemleak_object *object)
321{
322 return object->min_count == -1;
323}
324
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100325/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100326 * Objects are considered unreferenced only if their color is white, they have
327 * not be deleted and have a minimum age to avoid false positives caused by
328 * pointers temporarily stored in CPU registers.
329 */
330static int unreferenced_object(struct kmemleak_object *object)
331{
332 return (object->flags & OBJECT_ALLOCATED) && color_white(object) &&
Catalin Marinasacf49682009-06-26 17:38:29 +0100333 time_before_eq(object->jiffies + jiffies_min_age,
334 jiffies_last_scan);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100335}
336
337/*
Catalin Marinasbab4a342009-06-26 17:38:26 +0100338 * Printing of the unreferenced objects information to the seq file. The
339 * print_unreferenced function must be called with the object->lock held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100340 */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100341static void print_unreferenced(struct seq_file *seq,
342 struct kmemleak_object *object)
343{
344 int i;
345
Catalin Marinasbab4a342009-06-26 17:38:26 +0100346 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
347 object->pointer, object->size);
348 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu\n",
349 object->comm, object->pid, object->jiffies);
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100350 hex_dump_object(seq, object);
Catalin Marinasbab4a342009-06-26 17:38:26 +0100351 seq_printf(seq, " backtrace:\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100352
353 for (i = 0; i < object->trace_len; i++) {
354 void *ptr = (void *)object->trace[i];
Catalin Marinasbab4a342009-06-26 17:38:26 +0100355 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100356 }
357}
358
359/*
360 * Print the kmemleak_object information. This function is used mainly for
361 * debugging special cases when kmemleak operations. It must be called with
362 * the object->lock held.
363 */
364static void dump_object_info(struct kmemleak_object *object)
365{
366 struct stack_trace trace;
367
368 trace.nr_entries = object->trace_len;
369 trace.entries = object->trace;
370
Joe Perchesae281062009-06-23 14:40:26 +0100371 pr_notice("Object 0x%08lx (size %zu):\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100372 object->tree_node.start, object->size);
373 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
374 object->comm, object->pid, object->jiffies);
375 pr_notice(" min_count = %d\n", object->min_count);
376 pr_notice(" count = %d\n", object->count);
Catalin Marinas189d84e2009-08-27 14:29:15 +0100377 pr_notice(" flags = 0x%lx\n", object->flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100378 pr_notice(" backtrace:\n");
379 print_stack_trace(&trace, 4);
380}
381
382/*
383 * Look-up a memory block metadata (kmemleak_object) in the priority search
384 * tree based on a pointer value. If alias is 0, only values pointing to the
385 * beginning of the memory block are allowed. The kmemleak_lock must be held
386 * when calling this function.
387 */
388static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
389{
390 struct prio_tree_node *node;
391 struct prio_tree_iter iter;
392 struct kmemleak_object *object;
393
394 prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
395 node = prio_tree_next(&iter);
396 if (node) {
397 object = prio_tree_entry(node, struct kmemleak_object,
398 tree_node);
399 if (!alias && object->pointer != ptr) {
Joe Perchesae281062009-06-23 14:40:26 +0100400 kmemleak_warn("Found object by alias");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100401 object = NULL;
402 }
403 } else
404 object = NULL;
405
406 return object;
407}
408
409/*
410 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
411 * that once an object's use_count reached 0, the RCU freeing was already
412 * registered and the object should no longer be used. This function must be
413 * called under the protection of rcu_read_lock().
414 */
415static int get_object(struct kmemleak_object *object)
416{
417 return atomic_inc_not_zero(&object->use_count);
418}
419
420/*
421 * RCU callback to free a kmemleak_object.
422 */
423static void free_object_rcu(struct rcu_head *rcu)
424{
425 struct hlist_node *elem, *tmp;
426 struct kmemleak_scan_area *area;
427 struct kmemleak_object *object =
428 container_of(rcu, struct kmemleak_object, rcu);
429
430 /*
431 * Once use_count is 0 (guaranteed by put_object), there is no other
432 * code accessing this object, hence no need for locking.
433 */
434 hlist_for_each_entry_safe(area, elem, tmp, &object->area_list, node) {
435 hlist_del(elem);
436 kmem_cache_free(scan_area_cache, area);
437 }
438 kmem_cache_free(object_cache, object);
439}
440
441/*
442 * Decrement the object use_count. Once the count is 0, free the object using
443 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
444 * delete_object() path, the delayed RCU freeing ensures that there is no
445 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
446 * is also possible.
447 */
448static void put_object(struct kmemleak_object *object)
449{
450 if (!atomic_dec_and_test(&object->use_count))
451 return;
452
453 /* should only get here after delete_object was called */
454 WARN_ON(object->flags & OBJECT_ALLOCATED);
455
456 call_rcu(&object->rcu, free_object_rcu);
457}
458
459/*
460 * Look up an object in the prio search tree and increase its use_count.
461 */
462static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
463{
464 unsigned long flags;
465 struct kmemleak_object *object = NULL;
466
467 rcu_read_lock();
468 read_lock_irqsave(&kmemleak_lock, flags);
469 if (ptr >= min_addr && ptr < max_addr)
470 object = lookup_object(ptr, alias);
471 read_unlock_irqrestore(&kmemleak_lock, flags);
472
473 /* check whether the object is still available */
474 if (object && !get_object(object))
475 object = NULL;
476 rcu_read_unlock();
477
478 return object;
479}
480
481/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100482 * Save stack trace to the given array of MAX_TRACE size.
483 */
484static int __save_stack_trace(unsigned long *trace)
485{
486 struct stack_trace stack_trace;
487
488 stack_trace.max_entries = MAX_TRACE;
489 stack_trace.nr_entries = 0;
490 stack_trace.entries = trace;
491 stack_trace.skip = 2;
492 save_stack_trace(&stack_trace);
493
494 return stack_trace.nr_entries;
495}
496
497/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100498 * Create the metadata (struct kmemleak_object) corresponding to an allocated
499 * memory block and add it to the object_list and object_tree_root.
500 */
Catalin Marinasfd678962009-08-27 14:29:17 +0100501static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
502 int min_count, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100503{
504 unsigned long flags;
505 struct kmemleak_object *object;
506 struct prio_tree_node *node;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100507
Catalin Marinas216c04b2009-06-17 18:29:02 +0100508 object = kmem_cache_alloc(object_cache, gfp & GFP_KMEMLEAK_MASK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100509 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100510 kmemleak_stop("Cannot allocate a kmemleak_object structure\n");
Catalin Marinasfd678962009-08-27 14:29:17 +0100511 return NULL;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100512 }
513
514 INIT_LIST_HEAD(&object->object_list);
515 INIT_LIST_HEAD(&object->gray_list);
516 INIT_HLIST_HEAD(&object->area_list);
517 spin_lock_init(&object->lock);
518 atomic_set(&object->use_count, 1);
Catalin Marinas25873622009-07-07 10:32:58 +0100519 object->flags = OBJECT_ALLOCATED | OBJECT_NEW;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100520 object->pointer = ptr;
521 object->size = size;
522 object->min_count = min_count;
523 object->count = -1; /* no color initially */
524 object->jiffies = jiffies;
525
526 /* task information */
527 if (in_irq()) {
528 object->pid = 0;
529 strncpy(object->comm, "hardirq", sizeof(object->comm));
530 } else if (in_softirq()) {
531 object->pid = 0;
532 strncpy(object->comm, "softirq", sizeof(object->comm));
533 } else {
534 object->pid = current->pid;
535 /*
536 * There is a small chance of a race with set_task_comm(),
537 * however using get_task_comm() here may cause locking
538 * dependency issues with current->alloc_lock. In the worst
539 * case, the command line is not correct.
540 */
541 strncpy(object->comm, current->comm, sizeof(object->comm));
542 }
543
544 /* kernel backtrace */
Catalin Marinasfd678962009-08-27 14:29:17 +0100545 object->trace_len = __save_stack_trace(object->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100546
547 INIT_PRIO_TREE_NODE(&object->tree_node);
548 object->tree_node.start = ptr;
549 object->tree_node.last = ptr + size - 1;
550
551 write_lock_irqsave(&kmemleak_lock, flags);
552 min_addr = min(min_addr, ptr);
553 max_addr = max(max_addr, ptr + size);
554 node = prio_tree_insert(&object_tree_root, &object->tree_node);
555 /*
556 * The code calling the kernel does not yet have the pointer to the
557 * memory block to be able to free it. However, we still hold the
558 * kmemleak_lock here in case parts of the kernel started freeing
559 * random memory blocks.
560 */
561 if (node != &object->tree_node) {
562 unsigned long flags;
563
Joe Perchesae281062009-06-23 14:40:26 +0100564 kmemleak_stop("Cannot insert 0x%lx into the object search tree "
565 "(already existing)\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100566 object = lookup_object(ptr, 1);
567 spin_lock_irqsave(&object->lock, flags);
568 dump_object_info(object);
569 spin_unlock_irqrestore(&object->lock, flags);
570
571 goto out;
572 }
573 list_add_tail_rcu(&object->object_list, &object_list);
574out:
575 write_unlock_irqrestore(&kmemleak_lock, flags);
Catalin Marinasfd678962009-08-27 14:29:17 +0100576 return object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100577}
578
579/*
580 * Remove the metadata (struct kmemleak_object) for a memory block from the
581 * object_list and object_tree_root and decrement its use_count.
582 */
Catalin Marinas53238a62009-07-07 10:33:00 +0100583static void __delete_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100584{
585 unsigned long flags;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100586
587 write_lock_irqsave(&kmemleak_lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100588 prio_tree_remove(&object_tree_root, &object->tree_node);
589 list_del_rcu(&object->object_list);
590 write_unlock_irqrestore(&kmemleak_lock, flags);
591
592 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
Catalin Marinas53238a62009-07-07 10:33:00 +0100593 WARN_ON(atomic_read(&object->use_count) < 2);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100594
595 /*
596 * Locking here also ensures that the corresponding memory block
597 * cannot be freed when it is being scanned.
598 */
599 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100600 object->flags &= ~OBJECT_ALLOCATED;
601 spin_unlock_irqrestore(&object->lock, flags);
602 put_object(object);
603}
604
605/*
Catalin Marinas53238a62009-07-07 10:33:00 +0100606 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
607 * delete it.
608 */
609static void delete_object_full(unsigned long ptr)
610{
611 struct kmemleak_object *object;
612
613 object = find_and_get_object(ptr, 0);
614 if (!object) {
615#ifdef DEBUG
616 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
617 ptr);
618#endif
619 return;
620 }
621 __delete_object(object);
622 put_object(object);
623}
624
625/*
626 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
627 * delete it. If the memory block is partially freed, the function may create
628 * additional metadata for the remaining parts of the block.
629 */
630static void delete_object_part(unsigned long ptr, size_t size)
631{
632 struct kmemleak_object *object;
633 unsigned long start, end;
634
635 object = find_and_get_object(ptr, 1);
636 if (!object) {
637#ifdef DEBUG
638 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
639 "(size %zu)\n", ptr, size);
640#endif
641 return;
642 }
643 __delete_object(object);
644
645 /*
646 * Create one or two objects that may result from the memory block
647 * split. Note that partial freeing is only done by free_bootmem() and
648 * this happens before kmemleak_init() is called. The path below is
649 * only executed during early log recording in kmemleak_init(), so
650 * GFP_KERNEL is enough.
651 */
652 start = object->pointer;
653 end = object->pointer + object->size;
654 if (ptr > start)
655 create_object(start, ptr - start, object->min_count,
656 GFP_KERNEL);
657 if (ptr + size < end)
658 create_object(ptr + size, end - ptr - size, object->min_count,
659 GFP_KERNEL);
660
661 put_object(object);
662}
663/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100664 * Make a object permanently as gray-colored so that it can no longer be
665 * reported as a leak. This is used in general to mark a false positive.
666 */
667static void make_gray_object(unsigned long ptr)
668{
669 unsigned long flags;
670 struct kmemleak_object *object;
671
672 object = find_and_get_object(ptr, 0);
673 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100674 kmemleak_warn("Graying unknown object at 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100675 return;
676 }
677
678 spin_lock_irqsave(&object->lock, flags);
679 object->min_count = 0;
680 spin_unlock_irqrestore(&object->lock, flags);
681 put_object(object);
682}
683
684/*
685 * Mark the object as black-colored so that it is ignored from scans and
686 * reporting.
687 */
688static void make_black_object(unsigned long ptr)
689{
690 unsigned long flags;
691 struct kmemleak_object *object;
692
693 object = find_and_get_object(ptr, 0);
694 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100695 kmemleak_warn("Blacking unknown object at 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100696 return;
697 }
698
699 spin_lock_irqsave(&object->lock, flags);
700 object->min_count = -1;
Catalin Marinasaf986032009-08-27 14:29:12 +0100701 object->flags |= OBJECT_NO_SCAN;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100702 spin_unlock_irqrestore(&object->lock, flags);
703 put_object(object);
704}
705
706/*
707 * Add a scanning area to the object. If at least one such area is added,
708 * kmemleak will only scan these ranges rather than the whole memory block.
709 */
710static void add_scan_area(unsigned long ptr, unsigned long offset,
711 size_t length, gfp_t gfp)
712{
713 unsigned long flags;
714 struct kmemleak_object *object;
715 struct kmemleak_scan_area *area;
716
717 object = find_and_get_object(ptr, 0);
718 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100719 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
720 ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100721 return;
722 }
723
Catalin Marinas216c04b2009-06-17 18:29:02 +0100724 area = kmem_cache_alloc(scan_area_cache, gfp & GFP_KMEMLEAK_MASK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100725 if (!area) {
Joe Perchesae281062009-06-23 14:40:26 +0100726 kmemleak_warn("Cannot allocate a scan area\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100727 goto out;
728 }
729
730 spin_lock_irqsave(&object->lock, flags);
731 if (offset + length > object->size) {
Joe Perchesae281062009-06-23 14:40:26 +0100732 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100733 dump_object_info(object);
734 kmem_cache_free(scan_area_cache, area);
735 goto out_unlock;
736 }
737
738 INIT_HLIST_NODE(&area->node);
739 area->offset = offset;
740 area->length = length;
741
742 hlist_add_head(&area->node, &object->area_list);
743out_unlock:
744 spin_unlock_irqrestore(&object->lock, flags);
745out:
746 put_object(object);
747}
748
749/*
750 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
751 * pointer. Such object will not be scanned by kmemleak but references to it
752 * are searched.
753 */
754static void object_no_scan(unsigned long ptr)
755{
756 unsigned long flags;
757 struct kmemleak_object *object;
758
759 object = find_and_get_object(ptr, 0);
760 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100761 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100762 return;
763 }
764
765 spin_lock_irqsave(&object->lock, flags);
766 object->flags |= OBJECT_NO_SCAN;
767 spin_unlock_irqrestore(&object->lock, flags);
768 put_object(object);
769}
770
771/*
772 * Log an early kmemleak_* call to the early_log buffer. These calls will be
773 * processed later once kmemleak is fully initialized.
774 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100775static void __init log_early(int op_type, const void *ptr, size_t size,
776 int min_count, unsigned long offset, size_t length)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100777{
778 unsigned long flags;
779 struct early_log *log;
780
781 if (crt_early_log >= ARRAY_SIZE(early_log)) {
Catalin Marinasa9d90582009-06-25 10:16:11 +0100782 pr_warning("Early log buffer exceeded\n");
783 kmemleak_disable();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100784 return;
785 }
786
787 /*
788 * There is no need for locking since the kernel is still in UP mode
789 * at this stage. Disabling the IRQs is enough.
790 */
791 local_irq_save(flags);
792 log = &early_log[crt_early_log];
793 log->op_type = op_type;
794 log->ptr = ptr;
795 log->size = size;
796 log->min_count = min_count;
797 log->offset = offset;
798 log->length = length;
Catalin Marinasfd678962009-08-27 14:29:17 +0100799 if (op_type == KMEMLEAK_ALLOC)
800 log->trace_len = __save_stack_trace(log->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100801 crt_early_log++;
802 local_irq_restore(flags);
803}
804
805/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100806 * Log an early allocated block and populate the stack trace.
807 */
808static void early_alloc(struct early_log *log)
809{
810 struct kmemleak_object *object;
811 unsigned long flags;
812 int i;
813
814 if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
815 return;
816
817 /*
818 * RCU locking needed to ensure object is not freed via put_object().
819 */
820 rcu_read_lock();
821 object = create_object((unsigned long)log->ptr, log->size,
822 log->min_count, GFP_KERNEL);
823 spin_lock_irqsave(&object->lock, flags);
824 for (i = 0; i < log->trace_len; i++)
825 object->trace[i] = log->trace[i];
826 object->trace_len = log->trace_len;
827 spin_unlock_irqrestore(&object->lock, flags);
828 rcu_read_unlock();
829}
830
831/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100832 * Memory allocation function callback. This function is called from the
833 * kernel allocators when a new block is allocated (kmem_cache_alloc, kmalloc,
834 * vmalloc etc.).
835 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100836void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
837 gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100838{
839 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
840
841 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
842 create_object((unsigned long)ptr, size, min_count, gfp);
843 else if (atomic_read(&kmemleak_early_log))
844 log_early(KMEMLEAK_ALLOC, ptr, size, min_count, 0, 0);
845}
846EXPORT_SYMBOL_GPL(kmemleak_alloc);
847
848/*
849 * Memory freeing function callback. This function is called from the kernel
850 * allocators when a block is freed (kmem_cache_free, kfree, vfree etc.).
851 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100852void __ref kmemleak_free(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100853{
854 pr_debug("%s(0x%p)\n", __func__, ptr);
855
856 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinas53238a62009-07-07 10:33:00 +0100857 delete_object_full((unsigned long)ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100858 else if (atomic_read(&kmemleak_early_log))
859 log_early(KMEMLEAK_FREE, ptr, 0, 0, 0, 0);
860}
861EXPORT_SYMBOL_GPL(kmemleak_free);
862
863/*
Catalin Marinas53238a62009-07-07 10:33:00 +0100864 * Partial memory freeing function callback. This function is usually called
865 * from bootmem allocator when (part of) a memory block is freed.
866 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100867void __ref kmemleak_free_part(const void *ptr, size_t size)
Catalin Marinas53238a62009-07-07 10:33:00 +0100868{
869 pr_debug("%s(0x%p)\n", __func__, ptr);
870
871 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
872 delete_object_part((unsigned long)ptr, size);
873 else if (atomic_read(&kmemleak_early_log))
874 log_early(KMEMLEAK_FREE_PART, ptr, size, 0, 0, 0);
875}
876EXPORT_SYMBOL_GPL(kmemleak_free_part);
877
878/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100879 * Mark an already allocated memory block as a false positive. This will cause
880 * the block to no longer be reported as leak and always be scanned.
881 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100882void __ref kmemleak_not_leak(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100883{
884 pr_debug("%s(0x%p)\n", __func__, ptr);
885
886 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
887 make_gray_object((unsigned long)ptr);
888 else if (atomic_read(&kmemleak_early_log))
889 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0, 0, 0);
890}
891EXPORT_SYMBOL(kmemleak_not_leak);
892
893/*
894 * Ignore a memory block. This is usually done when it is known that the
895 * corresponding block is not a leak and does not contain any references to
896 * other allocated memory blocks.
897 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100898void __ref kmemleak_ignore(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100899{
900 pr_debug("%s(0x%p)\n", __func__, ptr);
901
902 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
903 make_black_object((unsigned long)ptr);
904 else if (atomic_read(&kmemleak_early_log))
905 log_early(KMEMLEAK_IGNORE, ptr, 0, 0, 0, 0);
906}
907EXPORT_SYMBOL(kmemleak_ignore);
908
909/*
910 * Limit the range to be scanned in an allocated memory block.
911 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100912void __ref kmemleak_scan_area(const void *ptr, unsigned long offset,
913 size_t length, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100914{
915 pr_debug("%s(0x%p)\n", __func__, ptr);
916
917 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
918 add_scan_area((unsigned long)ptr, offset, length, gfp);
919 else if (atomic_read(&kmemleak_early_log))
920 log_early(KMEMLEAK_SCAN_AREA, ptr, 0, 0, offset, length);
921}
922EXPORT_SYMBOL(kmemleak_scan_area);
923
924/*
925 * Inform kmemleak not to scan the given memory block.
926 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100927void __ref kmemleak_no_scan(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100928{
929 pr_debug("%s(0x%p)\n", __func__, ptr);
930
931 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
932 object_no_scan((unsigned long)ptr);
933 else if (atomic_read(&kmemleak_early_log))
934 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0, 0, 0);
935}
936EXPORT_SYMBOL(kmemleak_no_scan);
937
938/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100939 * Memory scanning is a long process and it needs to be interruptable. This
940 * function checks whether such interrupt condition occured.
941 */
942static int scan_should_stop(void)
943{
944 if (!atomic_read(&kmemleak_enabled))
945 return 1;
946
947 /*
948 * This function may be called from either process or kthread context,
949 * hence the need to check for both stop conditions.
950 */
951 if (current->mm)
952 return signal_pending(current);
953 else
954 return kthread_should_stop();
955
956 return 0;
957}
958
959/*
960 * Scan a memory block (exclusive range) for valid pointers and add those
961 * found to the gray list.
962 */
963static void scan_block(void *_start, void *_end,
Catalin Marinas4b8a9672009-07-07 10:32:56 +0100964 struct kmemleak_object *scanned, int allow_resched)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100965{
966 unsigned long *ptr;
967 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
968 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
969
970 for (ptr = start; ptr < end; ptr++) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100971 struct kmemleak_object *object;
Pekka Enberg8e019362009-08-27 14:50:00 +0100972 unsigned long flags;
973 unsigned long pointer;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100974
Catalin Marinas4b8a9672009-07-07 10:32:56 +0100975 if (allow_resched)
976 cond_resched();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100977 if (scan_should_stop())
978 break;
979
Pekka Enberg8e019362009-08-27 14:50:00 +0100980 /* don't scan uninitialized memory */
981 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
982 BYTES_PER_POINTER))
983 continue;
984
985 pointer = *ptr;
986
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100987 object = find_and_get_object(pointer, 1);
988 if (!object)
989 continue;
990 if (object == scanned) {
991 /* self referenced, ignore */
992 put_object(object);
993 continue;
994 }
995
996 /*
997 * Avoid the lockdep recursive warning on object->lock being
998 * previously acquired in scan_object(). These locks are
999 * enclosed by scan_mutex.
1000 */
1001 spin_lock_irqsave_nested(&object->lock, flags,
1002 SINGLE_DEPTH_NESTING);
1003 if (!color_white(object)) {
1004 /* non-orphan, ignored or new */
1005 spin_unlock_irqrestore(&object->lock, flags);
1006 put_object(object);
1007 continue;
1008 }
1009
1010 /*
1011 * Increase the object's reference count (number of pointers
1012 * to the memory block). If this count reaches the required
1013 * minimum, the object's color will become gray and it will be
1014 * added to the gray_list.
1015 */
1016 object->count++;
1017 if (color_gray(object))
1018 list_add_tail(&object->gray_list, &gray_list);
1019 else
1020 put_object(object);
1021 spin_unlock_irqrestore(&object->lock, flags);
1022 }
1023}
1024
1025/*
1026 * Scan a memory block corresponding to a kmemleak_object. A condition is
1027 * that object->use_count >= 1.
1028 */
1029static void scan_object(struct kmemleak_object *object)
1030{
1031 struct kmemleak_scan_area *area;
1032 struct hlist_node *elem;
1033 unsigned long flags;
1034
1035 /*
1036 * Once the object->lock is aquired, the corresponding memory block
1037 * cannot be freed (the same lock is aquired in delete_object).
1038 */
1039 spin_lock_irqsave(&object->lock, flags);
1040 if (object->flags & OBJECT_NO_SCAN)
1041 goto out;
1042 if (!(object->flags & OBJECT_ALLOCATED))
1043 /* already freed object */
1044 goto out;
Catalin Marinasaf986032009-08-27 14:29:12 +01001045 if (hlist_empty(&object->area_list)) {
1046 void *start = (void *)object->pointer;
1047 void *end = (void *)(object->pointer + object->size);
1048
1049 while (start < end && (object->flags & OBJECT_ALLOCATED) &&
1050 !(object->flags & OBJECT_NO_SCAN)) {
1051 scan_block(start, min(start + MAX_SCAN_SIZE, end),
1052 object, 0);
1053 start += MAX_SCAN_SIZE;
1054
1055 spin_unlock_irqrestore(&object->lock, flags);
1056 cond_resched();
1057 spin_lock_irqsave(&object->lock, flags);
1058 }
1059 } else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001060 hlist_for_each_entry(area, elem, &object->area_list, node)
1061 scan_block((void *)(object->pointer + area->offset),
1062 (void *)(object->pointer + area->offset
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001063 + area->length), object, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001064out:
1065 spin_unlock_irqrestore(&object->lock, flags);
1066}
1067
1068/*
1069 * Scan data sections and all the referenced memory blocks allocated via the
1070 * kernel's standard allocators. This function must be called with the
1071 * scan_mutex held.
1072 */
1073static void kmemleak_scan(void)
1074{
1075 unsigned long flags;
1076 struct kmemleak_object *object, *tmp;
1077 struct task_struct *task;
1078 int i;
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001079 int new_leaks = 0;
Catalin Marinas25873622009-07-07 10:32:58 +01001080 int gray_list_pass = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001081
Catalin Marinasacf49682009-06-26 17:38:29 +01001082 jiffies_last_scan = jiffies;
1083
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001084 /* prepare the kmemleak_object's */
1085 rcu_read_lock();
1086 list_for_each_entry_rcu(object, &object_list, object_list) {
1087 spin_lock_irqsave(&object->lock, flags);
1088#ifdef DEBUG
1089 /*
1090 * With a few exceptions there should be a maximum of
1091 * 1 reference to any object at this point.
1092 */
1093 if (atomic_read(&object->use_count) > 1) {
Joe Perchesae281062009-06-23 14:40:26 +01001094 pr_debug("object->use_count = %d\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001095 atomic_read(&object->use_count));
1096 dump_object_info(object);
1097 }
1098#endif
1099 /* reset the reference count (whiten the object) */
1100 object->count = 0;
Catalin Marinas25873622009-07-07 10:32:58 +01001101 object->flags &= ~OBJECT_NEW;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001102 if (color_gray(object) && get_object(object))
1103 list_add_tail(&object->gray_list, &gray_list);
1104
1105 spin_unlock_irqrestore(&object->lock, flags);
1106 }
1107 rcu_read_unlock();
1108
1109 /* data/bss scanning */
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001110 scan_block(_sdata, _edata, NULL, 1);
1111 scan_block(__bss_start, __bss_stop, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001112
1113#ifdef CONFIG_SMP
1114 /* per-cpu sections scanning */
1115 for_each_possible_cpu(i)
1116 scan_block(__per_cpu_start + per_cpu_offset(i),
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001117 __per_cpu_end + per_cpu_offset(i), NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001118#endif
1119
1120 /*
1121 * Struct page scanning for each node. The code below is not yet safe
1122 * with MEMORY_HOTPLUG.
1123 */
1124 for_each_online_node(i) {
1125 pg_data_t *pgdat = NODE_DATA(i);
1126 unsigned long start_pfn = pgdat->node_start_pfn;
1127 unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
1128 unsigned long pfn;
1129
1130 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1131 struct page *page;
1132
1133 if (!pfn_valid(pfn))
1134 continue;
1135 page = pfn_to_page(pfn);
1136 /* only scan if page is in use */
1137 if (page_count(page) == 0)
1138 continue;
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001139 scan_block(page, page + 1, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001140 }
1141 }
1142
1143 /*
1144 * Scanning the task stacks may introduce false negatives and it is
1145 * not enabled by default.
1146 */
1147 if (kmemleak_stack_scan) {
1148 read_lock(&tasklist_lock);
1149 for_each_process(task)
1150 scan_block(task_stack_page(task),
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001151 task_stack_page(task) + THREAD_SIZE,
1152 NULL, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001153 read_unlock(&tasklist_lock);
1154 }
1155
1156 /*
1157 * Scan the objects already referenced from the sections scanned
1158 * above. More objects will be referenced and, if there are no memory
1159 * leaks, all the objects will be scanned. The list traversal is safe
1160 * for both tail additions and removals from inside the loop. The
1161 * kmemleak objects cannot be freed from outside the loop because their
1162 * use_count was increased.
1163 */
Catalin Marinas25873622009-07-07 10:32:58 +01001164repeat:
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001165 object = list_entry(gray_list.next, typeof(*object), gray_list);
1166 while (&object->gray_list != &gray_list) {
Ingo Molnar57d81f62009-07-01 09:43:53 +02001167 cond_resched();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001168
1169 /* may add new objects to the list */
1170 if (!scan_should_stop())
1171 scan_object(object);
1172
1173 tmp = list_entry(object->gray_list.next, typeof(*object),
1174 gray_list);
1175
1176 /* remove the object from the list and release it */
1177 list_del(&object->gray_list);
1178 put_object(object);
1179
1180 object = tmp;
1181 }
Catalin Marinas25873622009-07-07 10:32:58 +01001182
1183 if (scan_should_stop() || ++gray_list_pass >= GRAY_LIST_PASSES)
1184 goto scan_end;
1185
1186 /*
1187 * Check for new objects allocated during this scanning and add them
1188 * to the gray list.
1189 */
1190 rcu_read_lock();
1191 list_for_each_entry_rcu(object, &object_list, object_list) {
1192 spin_lock_irqsave(&object->lock, flags);
1193 if ((object->flags & OBJECT_NEW) && !color_black(object) &&
1194 get_object(object)) {
1195 object->flags &= ~OBJECT_NEW;
1196 list_add_tail(&object->gray_list, &gray_list);
1197 }
1198 spin_unlock_irqrestore(&object->lock, flags);
1199 }
1200 rcu_read_unlock();
1201
1202 if (!list_empty(&gray_list))
1203 goto repeat;
1204
1205scan_end:
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001206 WARN_ON(!list_empty(&gray_list));
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001207
1208 /*
Catalin Marinas25873622009-07-07 10:32:58 +01001209 * If scanning was stopped or new objects were being allocated at a
1210 * higher rate than gray list scanning, do not report any new
1211 * unreferenced objects.
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001212 */
Catalin Marinas25873622009-07-07 10:32:58 +01001213 if (scan_should_stop() || gray_list_pass >= GRAY_LIST_PASSES)
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001214 return;
1215
1216 /*
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001217 * Scanning result reporting.
1218 */
1219 rcu_read_lock();
1220 list_for_each_entry_rcu(object, &object_list, object_list) {
1221 spin_lock_irqsave(&object->lock, flags);
1222 if (unreferenced_object(object) &&
1223 !(object->flags & OBJECT_REPORTED)) {
1224 object->flags |= OBJECT_REPORTED;
1225 new_leaks++;
1226 }
1227 spin_unlock_irqrestore(&object->lock, flags);
1228 }
1229 rcu_read_unlock();
1230
1231 if (new_leaks)
1232 pr_info("%d new suspected memory leaks (see "
1233 "/sys/kernel/debug/kmemleak)\n", new_leaks);
1234
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001235}
1236
1237/*
1238 * Thread function performing automatic memory scanning. Unreferenced objects
1239 * at the end of a memory scan are reported but only the first time.
1240 */
1241static int kmemleak_scan_thread(void *arg)
1242{
1243 static int first_run = 1;
1244
Joe Perchesae281062009-06-23 14:40:26 +01001245 pr_info("Automatic memory scanning thread started\n");
Catalin Marinasbf2a76b2009-07-07 10:32:55 +01001246 set_user_nice(current, 10);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001247
1248 /*
1249 * Wait before the first scan to allow the system to fully initialize.
1250 */
1251 if (first_run) {
1252 first_run = 0;
1253 ssleep(SECS_FIRST_SCAN);
1254 }
1255
1256 while (!kthread_should_stop()) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001257 signed long timeout = jiffies_scan_wait;
1258
1259 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001260 kmemleak_scan();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001261 mutex_unlock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001262
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001263 /* wait before the next scan */
1264 while (timeout && !kthread_should_stop())
1265 timeout = schedule_timeout_interruptible(timeout);
1266 }
1267
Joe Perchesae281062009-06-23 14:40:26 +01001268 pr_info("Automatic memory scanning thread ended\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001269
1270 return 0;
1271}
1272
1273/*
1274 * Start the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001275 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001276 */
1277void start_scan_thread(void)
1278{
1279 if (scan_thread)
1280 return;
1281 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1282 if (IS_ERR(scan_thread)) {
Joe Perchesae281062009-06-23 14:40:26 +01001283 pr_warning("Failed to create the scan thread\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001284 scan_thread = NULL;
1285 }
1286}
1287
1288/*
1289 * Stop the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001290 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001291 */
1292void stop_scan_thread(void)
1293{
1294 if (scan_thread) {
1295 kthread_stop(scan_thread);
1296 scan_thread = NULL;
1297 }
1298}
1299
1300/*
1301 * Iterate over the object_list and return the first valid object at or after
1302 * the required position with its use_count incremented. The function triggers
1303 * a memory scanning when the pos argument points to the first position.
1304 */
1305static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1306{
1307 struct kmemleak_object *object;
1308 loff_t n = *pos;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001309 int err;
1310
1311 err = mutex_lock_interruptible(&scan_mutex);
1312 if (err < 0)
1313 return ERR_PTR(err);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001314
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001315 rcu_read_lock();
1316 list_for_each_entry_rcu(object, &object_list, object_list) {
1317 if (n-- > 0)
1318 continue;
1319 if (get_object(object))
1320 goto out;
1321 }
1322 object = NULL;
1323out:
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001324 return object;
1325}
1326
1327/*
1328 * Return the next object in the object_list. The function decrements the
1329 * use_count of the previous object and increases that of the next one.
1330 */
1331static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1332{
1333 struct kmemleak_object *prev_obj = v;
1334 struct kmemleak_object *next_obj = NULL;
1335 struct list_head *n = &prev_obj->object_list;
1336
1337 ++(*pos);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001338
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001339 list_for_each_continue_rcu(n, &object_list) {
1340 next_obj = list_entry(n, struct kmemleak_object, object_list);
1341 if (get_object(next_obj))
1342 break;
1343 }
Catalin Marinas288c8572009-07-07 10:32:57 +01001344
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001345 put_object(prev_obj);
1346 return next_obj;
1347}
1348
1349/*
1350 * Decrement the use_count of the last object required, if any.
1351 */
1352static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1353{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001354 if (!IS_ERR(v)) {
1355 /*
1356 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1357 * waiting was interrupted, so only release it if !IS_ERR.
1358 */
Catalin Marinasf5886c72009-07-29 16:26:57 +01001359 rcu_read_unlock();
Catalin Marinasb87324d2009-07-07 10:32:58 +01001360 mutex_unlock(&scan_mutex);
1361 if (v)
1362 put_object(v);
1363 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001364}
1365
1366/*
1367 * Print the information for an unreferenced object to the seq file.
1368 */
1369static int kmemleak_seq_show(struct seq_file *seq, void *v)
1370{
1371 struct kmemleak_object *object = v;
1372 unsigned long flags;
1373
1374 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas288c8572009-07-07 10:32:57 +01001375 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001376 print_unreferenced(seq, object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001377 spin_unlock_irqrestore(&object->lock, flags);
1378 return 0;
1379}
1380
1381static const struct seq_operations kmemleak_seq_ops = {
1382 .start = kmemleak_seq_start,
1383 .next = kmemleak_seq_next,
1384 .stop = kmemleak_seq_stop,
1385 .show = kmemleak_seq_show,
1386};
1387
1388static int kmemleak_open(struct inode *inode, struct file *file)
1389{
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001390 if (!atomic_read(&kmemleak_enabled))
1391 return -EBUSY;
1392
Catalin Marinasb87324d2009-07-07 10:32:58 +01001393 return seq_open(file, &kmemleak_seq_ops);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001394}
1395
1396static int kmemleak_release(struct inode *inode, struct file *file)
1397{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001398 return seq_release(inode, file);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001399}
1400
Catalin Marinas189d84e2009-08-27 14:29:15 +01001401static int dump_str_object_info(const char *str)
1402{
1403 unsigned long flags;
1404 struct kmemleak_object *object;
1405 unsigned long addr;
1406
1407 addr= simple_strtoul(str, NULL, 0);
1408 object = find_and_get_object(addr, 0);
1409 if (!object) {
1410 pr_info("Unknown object at 0x%08lx\n", addr);
1411 return -EINVAL;
1412 }
1413
1414 spin_lock_irqsave(&object->lock, flags);
1415 dump_object_info(object);
1416 spin_unlock_irqrestore(&object->lock, flags);
1417
1418 put_object(object);
1419 return 0;
1420}
1421
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001422/*
1423 * File write operation to configure kmemleak at run-time. The following
1424 * commands can be written to the /sys/kernel/debug/kmemleak file:
1425 * off - disable kmemleak (irreversible)
1426 * stack=on - enable the task stacks scanning
1427 * stack=off - disable the tasks stacks scanning
1428 * scan=on - start the automatic memory scanning thread
1429 * scan=off - stop the automatic memory scanning thread
1430 * scan=... - set the automatic memory scanning period in seconds (0 to
1431 * disable it)
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001432 * scan - trigger a memory scan
Catalin Marinas189d84e2009-08-27 14:29:15 +01001433 * dump=... - dump information about the object found at the given address
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001434 */
1435static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1436 size_t size, loff_t *ppos)
1437{
1438 char buf[64];
1439 int buf_size;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001440 int ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001441
1442 buf_size = min(size, (sizeof(buf) - 1));
1443 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1444 return -EFAULT;
1445 buf[buf_size] = 0;
1446
Catalin Marinasb87324d2009-07-07 10:32:58 +01001447 ret = mutex_lock_interruptible(&scan_mutex);
1448 if (ret < 0)
1449 return ret;
1450
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001451 if (strncmp(buf, "off", 3) == 0)
1452 kmemleak_disable();
1453 else if (strncmp(buf, "stack=on", 8) == 0)
1454 kmemleak_stack_scan = 1;
1455 else if (strncmp(buf, "stack=off", 9) == 0)
1456 kmemleak_stack_scan = 0;
1457 else if (strncmp(buf, "scan=on", 7) == 0)
1458 start_scan_thread();
1459 else if (strncmp(buf, "scan=off", 8) == 0)
1460 stop_scan_thread();
1461 else if (strncmp(buf, "scan=", 5) == 0) {
1462 unsigned long secs;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001463
Catalin Marinasb87324d2009-07-07 10:32:58 +01001464 ret = strict_strtoul(buf + 5, 0, &secs);
1465 if (ret < 0)
1466 goto out;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001467 stop_scan_thread();
1468 if (secs) {
1469 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1470 start_scan_thread();
1471 }
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001472 } else if (strncmp(buf, "scan", 4) == 0)
1473 kmemleak_scan();
Catalin Marinas189d84e2009-08-27 14:29:15 +01001474 else if (strncmp(buf, "dump=", 5) == 0)
1475 ret = dump_str_object_info(buf + 5);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001476 else
Catalin Marinasb87324d2009-07-07 10:32:58 +01001477 ret = -EINVAL;
1478
1479out:
1480 mutex_unlock(&scan_mutex);
1481 if (ret < 0)
1482 return ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001483
1484 /* ignore the rest of the buffer, only one command at a time */
1485 *ppos += size;
1486 return size;
1487}
1488
1489static const struct file_operations kmemleak_fops = {
1490 .owner = THIS_MODULE,
1491 .open = kmemleak_open,
1492 .read = seq_read,
1493 .write = kmemleak_write,
1494 .llseek = seq_lseek,
1495 .release = kmemleak_release,
1496};
1497
1498/*
1499 * Perform the freeing of the kmemleak internal objects after waiting for any
1500 * current memory scan to complete.
1501 */
1502static int kmemleak_cleanup_thread(void *arg)
1503{
1504 struct kmemleak_object *object;
1505
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001506 mutex_lock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001507 stop_scan_thread();
1508
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001509 rcu_read_lock();
1510 list_for_each_entry_rcu(object, &object_list, object_list)
Catalin Marinas53238a62009-07-07 10:33:00 +01001511 delete_object_full(object->pointer);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001512 rcu_read_unlock();
1513 mutex_unlock(&scan_mutex);
1514
1515 return 0;
1516}
1517
1518/*
1519 * Start the clean-up thread.
1520 */
1521static void kmemleak_cleanup(void)
1522{
1523 struct task_struct *cleanup_thread;
1524
1525 cleanup_thread = kthread_run(kmemleak_cleanup_thread, NULL,
1526 "kmemleak-clean");
1527 if (IS_ERR(cleanup_thread))
Joe Perchesae281062009-06-23 14:40:26 +01001528 pr_warning("Failed to create the clean-up thread\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001529}
1530
1531/*
1532 * Disable kmemleak. No memory allocation/freeing will be traced once this
1533 * function is called. Disabling kmemleak is an irreversible operation.
1534 */
1535static void kmemleak_disable(void)
1536{
1537 /* atomically check whether it was already invoked */
1538 if (atomic_cmpxchg(&kmemleak_error, 0, 1))
1539 return;
1540
1541 /* stop any memory operation tracing */
1542 atomic_set(&kmemleak_early_log, 0);
1543 atomic_set(&kmemleak_enabled, 0);
1544
1545 /* check whether it is too early for a kernel thread */
1546 if (atomic_read(&kmemleak_initialized))
1547 kmemleak_cleanup();
1548
1549 pr_info("Kernel memory leak detector disabled\n");
1550}
1551
1552/*
1553 * Allow boot-time kmemleak disabling (enabled by default).
1554 */
1555static int kmemleak_boot_config(char *str)
1556{
1557 if (!str)
1558 return -EINVAL;
1559 if (strcmp(str, "off") == 0)
1560 kmemleak_disable();
1561 else if (strcmp(str, "on") != 0)
1562 return -EINVAL;
1563 return 0;
1564}
1565early_param("kmemleak", kmemleak_boot_config);
1566
1567/*
Catalin Marinas20301172009-06-17 18:29:04 +01001568 * Kmemleak initialization.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001569 */
1570void __init kmemleak_init(void)
1571{
1572 int i;
1573 unsigned long flags;
1574
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001575 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1576 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1577
1578 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1579 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1580 INIT_PRIO_TREE_ROOT(&object_tree_root);
1581
1582 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1583 local_irq_save(flags);
1584 if (!atomic_read(&kmemleak_error)) {
1585 atomic_set(&kmemleak_enabled, 1);
1586 atomic_set(&kmemleak_early_log, 0);
1587 }
1588 local_irq_restore(flags);
1589
1590 /*
1591 * This is the point where tracking allocations is safe. Automatic
1592 * scanning is started during the late initcall. Add the early logged
1593 * callbacks to the kmemleak infrastructure.
1594 */
1595 for (i = 0; i < crt_early_log; i++) {
1596 struct early_log *log = &early_log[i];
1597
1598 switch (log->op_type) {
1599 case KMEMLEAK_ALLOC:
Catalin Marinasfd678962009-08-27 14:29:17 +01001600 early_alloc(log);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001601 break;
1602 case KMEMLEAK_FREE:
1603 kmemleak_free(log->ptr);
1604 break;
Catalin Marinas53238a62009-07-07 10:33:00 +01001605 case KMEMLEAK_FREE_PART:
1606 kmemleak_free_part(log->ptr, log->size);
1607 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001608 case KMEMLEAK_NOT_LEAK:
1609 kmemleak_not_leak(log->ptr);
1610 break;
1611 case KMEMLEAK_IGNORE:
1612 kmemleak_ignore(log->ptr);
1613 break;
1614 case KMEMLEAK_SCAN_AREA:
1615 kmemleak_scan_area(log->ptr, log->offset, log->length,
1616 GFP_KERNEL);
1617 break;
1618 case KMEMLEAK_NO_SCAN:
1619 kmemleak_no_scan(log->ptr);
1620 break;
1621 default:
1622 WARN_ON(1);
1623 }
1624 }
1625}
1626
1627/*
1628 * Late initialization function.
1629 */
1630static int __init kmemleak_late_init(void)
1631{
1632 struct dentry *dentry;
1633
1634 atomic_set(&kmemleak_initialized, 1);
1635
1636 if (atomic_read(&kmemleak_error)) {
1637 /*
1638 * Some error occured and kmemleak was disabled. There is a
1639 * small chance that kmemleak_disable() was called immediately
1640 * after setting kmemleak_initialized and we may end up with
1641 * two clean-up threads but serialized by scan_mutex.
1642 */
1643 kmemleak_cleanup();
1644 return -ENOMEM;
1645 }
1646
1647 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1648 &kmemleak_fops);
1649 if (!dentry)
Joe Perchesae281062009-06-23 14:40:26 +01001650 pr_warning("Failed to create the debugfs kmemleak file\n");
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001651 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001652 start_scan_thread();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001653 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001654
1655 pr_info("Kernel memory leak detector initialized\n");
1656
1657 return 0;
1658}
1659late_initcall(kmemleak_late_init);