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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>
Catalin Marinas179a8102009-09-07 10:14:42 +010095#include <linux/workqueue.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010096
97#include <asm/sections.h>
98#include <asm/processor.h>
99#include <asm/atomic.h>
100
Pekka Enberg8e019362009-08-27 14:50:00 +0100101#include <linux/kmemcheck.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100102#include <linux/kmemleak.h>
103
104/*
105 * Kmemleak configuration and common defines.
106 */
107#define MAX_TRACE 16 /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100108#define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100109#define SECS_FIRST_SCAN 60 /* delay before the first scan */
110#define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
Catalin Marinas25873622009-07-07 10:32:58 +0100111#define GRAY_LIST_PASSES 25 /* maximum number of gray list scans */
Catalin Marinasaf986032009-08-27 14:29:12 +0100112#define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100113
114#define BYTES_PER_POINTER sizeof(void *)
115
Catalin Marinas216c04b2009-06-17 18:29:02 +0100116/* GFP bitmask for kmemleak internal allocations */
117#define GFP_KMEMLEAK_MASK (GFP_KERNEL | GFP_ATOMIC)
118
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100119/* scanning area inside a memory block */
120struct kmemleak_scan_area {
121 struct hlist_node node;
122 unsigned long offset;
123 size_t length;
124};
125
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700126#define KMEMLEAK_GREY 0
127#define KMEMLEAK_BLACK -1
128
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100129/*
130 * Structure holding the metadata for each allocated memory block.
131 * Modifications to such objects should be made while holding the
132 * object->lock. Insertions or deletions from object_list, gray_list or
133 * tree_node are already protected by the corresponding locks or mutex (see
134 * the notes on locking above). These objects are reference-counted
135 * (use_count) and freed using the RCU mechanism.
136 */
137struct kmemleak_object {
138 spinlock_t lock;
139 unsigned long flags; /* object status flags */
140 struct list_head object_list;
141 struct list_head gray_list;
142 struct prio_tree_node tree_node;
143 struct rcu_head rcu; /* object_list lockless traversal */
144 /* object usage count; object freed when use_count == 0 */
145 atomic_t use_count;
146 unsigned long pointer;
147 size_t size;
148 /* minimum number of a pointers found before it is considered leak */
149 int min_count;
150 /* the total number of pointers found pointing to this object */
151 int count;
152 /* memory ranges to be scanned inside an object (empty for all) */
153 struct hlist_head area_list;
154 unsigned long trace[MAX_TRACE];
155 unsigned int trace_len;
156 unsigned long jiffies; /* creation timestamp */
157 pid_t pid; /* pid of the current task */
158 char comm[TASK_COMM_LEN]; /* executable name */
159};
160
161/* flag representing the memory block allocation status */
162#define OBJECT_ALLOCATED (1 << 0)
163/* flag set after the first reporting of an unreference object */
164#define OBJECT_REPORTED (1 << 1)
165/* flag set to not scan the object */
166#define OBJECT_NO_SCAN (1 << 2)
Catalin Marinas25873622009-07-07 10:32:58 +0100167/* flag set on newly allocated objects */
168#define OBJECT_NEW (1 << 3)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100169
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100170/* number of bytes to print per line; must be 16 or 32 */
171#define HEX_ROW_SIZE 16
172/* number of bytes to print at a time (1, 2, 4, 8) */
173#define HEX_GROUP_SIZE 1
174/* include ASCII after the hex output */
175#define HEX_ASCII 1
176/* max number of lines to be printed */
177#define HEX_MAX_LINES 2
178
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100179/* the list of all allocated objects */
180static LIST_HEAD(object_list);
181/* the list of gray-colored objects (see color_gray comment below) */
182static LIST_HEAD(gray_list);
183/* prio search tree for object boundaries */
184static struct prio_tree_root object_tree_root;
185/* rw_lock protecting the access to object_list and prio_tree_root */
186static DEFINE_RWLOCK(kmemleak_lock);
187
188/* allocation caches for kmemleak internal data */
189static struct kmem_cache *object_cache;
190static struct kmem_cache *scan_area_cache;
191
192/* set if tracing memory operations is enabled */
193static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
194/* set in the late_initcall if there were no errors */
195static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
196/* enables or disables early logging of the memory operations */
197static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
198/* set if a fata kmemleak error has occurred */
199static atomic_t kmemleak_error = ATOMIC_INIT(0);
200
201/* minimum and maximum address that may be valid pointers */
202static unsigned long min_addr = ULONG_MAX;
203static unsigned long max_addr;
204
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100205static struct task_struct *scan_thread;
Catalin Marinasacf49682009-06-26 17:38:29 +0100206/* used to avoid reporting of recently allocated objects */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100207static unsigned long jiffies_min_age;
Catalin Marinasacf49682009-06-26 17:38:29 +0100208static unsigned long jiffies_last_scan;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100209/* delay between automatic memory scannings */
210static signed long jiffies_scan_wait;
211/* enables or disables the task stacks scanning */
Catalin Marinase0a2a162009-06-26 17:38:25 +0100212static int kmemleak_stack_scan = 1;
Catalin Marinas4698c1f2009-06-26 17:38:27 +0100213/* protects the memory scanning, parameters and debug/kmemleak file access */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100214static DEFINE_MUTEX(scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100215
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100216/*
Catalin Marinas20301172009-06-17 18:29:04 +0100217 * Early object allocation/freeing logging. Kmemleak is initialized after the
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100218 * kernel allocator. However, both the kernel allocator and kmemleak may
Catalin Marinas20301172009-06-17 18:29:04 +0100219 * allocate memory blocks which need to be tracked. Kmemleak defines an
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100220 * arbitrary buffer to hold the allocation/freeing information before it is
221 * fully initialized.
222 */
223
224/* kmemleak operation type for early logging */
225enum {
226 KMEMLEAK_ALLOC,
227 KMEMLEAK_FREE,
Catalin Marinas53238a62009-07-07 10:33:00 +0100228 KMEMLEAK_FREE_PART,
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100229 KMEMLEAK_NOT_LEAK,
230 KMEMLEAK_IGNORE,
231 KMEMLEAK_SCAN_AREA,
232 KMEMLEAK_NO_SCAN
233};
234
235/*
236 * Structure holding the information passed to kmemleak callbacks during the
237 * early logging.
238 */
239struct early_log {
240 int op_type; /* kmemleak operation type */
241 const void *ptr; /* allocated/freed memory block */
242 size_t size; /* memory block size */
243 int min_count; /* minimum reference count */
244 unsigned long offset; /* scan area offset */
245 size_t length; /* scan area length */
Catalin Marinasfd678962009-08-27 14:29:17 +0100246 unsigned long trace[MAX_TRACE]; /* stack trace */
247 unsigned int trace_len; /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100248};
249
250/* early logging buffer and current position */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100251static struct early_log
252 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
253static int crt_early_log __initdata;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100254
255static void kmemleak_disable(void);
256
257/*
258 * Print a warning and dump the stack trace.
259 */
260#define kmemleak_warn(x...) do { \
261 pr_warning(x); \
262 dump_stack(); \
263} while (0)
264
265/*
266 * Macro invoked when a serious kmemleak condition occured and cannot be
Catalin Marinas20301172009-06-17 18:29:04 +0100267 * recovered from. Kmemleak will be disabled and further allocation/freeing
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100268 * tracing no longer available.
269 */
Catalin Marinas000814f2009-06-17 18:29:03 +0100270#define kmemleak_stop(x...) do { \
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100271 kmemleak_warn(x); \
272 kmemleak_disable(); \
273} while (0)
274
275/*
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100276 * Printing of the objects hex dump to the seq file. The number of lines to be
277 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
278 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
279 * with the object->lock held.
280 */
281static void hex_dump_object(struct seq_file *seq,
282 struct kmemleak_object *object)
283{
284 const u8 *ptr = (const u8 *)object->pointer;
285 int i, len, remaining;
286 unsigned char linebuf[HEX_ROW_SIZE * 5];
287
288 /* limit the number of lines to HEX_MAX_LINES */
289 remaining = len =
290 min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
291
292 seq_printf(seq, " hex dump (first %d bytes):\n", len);
293 for (i = 0; i < len; i += HEX_ROW_SIZE) {
294 int linelen = min(remaining, HEX_ROW_SIZE);
295
296 remaining -= HEX_ROW_SIZE;
297 hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
298 HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
299 HEX_ASCII);
300 seq_printf(seq, " %s\n", linebuf);
301 }
302}
303
304/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100305 * Object colors, encoded with count and min_count:
306 * - white - orphan object, not enough references to it (count < min_count)
307 * - gray - not orphan, not marked as false positive (min_count == 0) or
308 * sufficient references to it (count >= min_count)
309 * - black - ignore, it doesn't contain references (e.g. text section)
310 * (min_count == -1). No function defined for this color.
311 * Newly created objects don't have any color assigned (object->count == -1)
312 * before the next memory scan when they become white.
313 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100314static bool color_white(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100315{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700316 return object->count != KMEMLEAK_BLACK &&
317 object->count < object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100318}
319
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100320static bool color_gray(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100321{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700322 return object->min_count != KMEMLEAK_BLACK &&
323 object->count >= object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100324}
325
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100326static bool color_black(const struct kmemleak_object *object)
Catalin Marinas25873622009-07-07 10:32:58 +0100327{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700328 return object->min_count == KMEMLEAK_BLACK;
Catalin Marinas25873622009-07-07 10:32:58 +0100329}
330
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100331/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100332 * Objects are considered unreferenced only if their color is white, they have
333 * not be deleted and have a minimum age to avoid false positives caused by
334 * pointers temporarily stored in CPU registers.
335 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100336static bool unreferenced_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100337{
338 return (object->flags & OBJECT_ALLOCATED) && color_white(object) &&
Catalin Marinasacf49682009-06-26 17:38:29 +0100339 time_before_eq(object->jiffies + jiffies_min_age,
340 jiffies_last_scan);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100341}
342
343/*
Catalin Marinasbab4a342009-06-26 17:38:26 +0100344 * Printing of the unreferenced objects information to the seq file. The
345 * print_unreferenced function must be called with the object->lock held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100346 */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100347static void print_unreferenced(struct seq_file *seq,
348 struct kmemleak_object *object)
349{
350 int i;
351
Catalin Marinasbab4a342009-06-26 17:38:26 +0100352 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
353 object->pointer, object->size);
354 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu\n",
355 object->comm, object->pid, object->jiffies);
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100356 hex_dump_object(seq, object);
Catalin Marinasbab4a342009-06-26 17:38:26 +0100357 seq_printf(seq, " backtrace:\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100358
359 for (i = 0; i < object->trace_len; i++) {
360 void *ptr = (void *)object->trace[i];
Catalin Marinasbab4a342009-06-26 17:38:26 +0100361 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100362 }
363}
364
365/*
366 * Print the kmemleak_object information. This function is used mainly for
367 * debugging special cases when kmemleak operations. It must be called with
368 * the object->lock held.
369 */
370static void dump_object_info(struct kmemleak_object *object)
371{
372 struct stack_trace trace;
373
374 trace.nr_entries = object->trace_len;
375 trace.entries = object->trace;
376
Joe Perchesae281062009-06-23 14:40:26 +0100377 pr_notice("Object 0x%08lx (size %zu):\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100378 object->tree_node.start, object->size);
379 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
380 object->comm, object->pid, object->jiffies);
381 pr_notice(" min_count = %d\n", object->min_count);
382 pr_notice(" count = %d\n", object->count);
Catalin Marinas189d84e2009-08-27 14:29:15 +0100383 pr_notice(" flags = 0x%lx\n", object->flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100384 pr_notice(" backtrace:\n");
385 print_stack_trace(&trace, 4);
386}
387
388/*
389 * Look-up a memory block metadata (kmemleak_object) in the priority search
390 * tree based on a pointer value. If alias is 0, only values pointing to the
391 * beginning of the memory block are allowed. The kmemleak_lock must be held
392 * when calling this function.
393 */
394static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
395{
396 struct prio_tree_node *node;
397 struct prio_tree_iter iter;
398 struct kmemleak_object *object;
399
400 prio_tree_iter_init(&iter, &object_tree_root, ptr, ptr);
401 node = prio_tree_next(&iter);
402 if (node) {
403 object = prio_tree_entry(node, struct kmemleak_object,
404 tree_node);
405 if (!alias && object->pointer != ptr) {
Joe Perchesae281062009-06-23 14:40:26 +0100406 kmemleak_warn("Found object by alias");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100407 object = NULL;
408 }
409 } else
410 object = NULL;
411
412 return object;
413}
414
415/*
416 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
417 * that once an object's use_count reached 0, the RCU freeing was already
418 * registered and the object should no longer be used. This function must be
419 * called under the protection of rcu_read_lock().
420 */
421static int get_object(struct kmemleak_object *object)
422{
423 return atomic_inc_not_zero(&object->use_count);
424}
425
426/*
427 * RCU callback to free a kmemleak_object.
428 */
429static void free_object_rcu(struct rcu_head *rcu)
430{
431 struct hlist_node *elem, *tmp;
432 struct kmemleak_scan_area *area;
433 struct kmemleak_object *object =
434 container_of(rcu, struct kmemleak_object, rcu);
435
436 /*
437 * Once use_count is 0 (guaranteed by put_object), there is no other
438 * code accessing this object, hence no need for locking.
439 */
440 hlist_for_each_entry_safe(area, elem, tmp, &object->area_list, node) {
441 hlist_del(elem);
442 kmem_cache_free(scan_area_cache, area);
443 }
444 kmem_cache_free(object_cache, object);
445}
446
447/*
448 * Decrement the object use_count. Once the count is 0, free the object using
449 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
450 * delete_object() path, the delayed RCU freeing ensures that there is no
451 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
452 * is also possible.
453 */
454static void put_object(struct kmemleak_object *object)
455{
456 if (!atomic_dec_and_test(&object->use_count))
457 return;
458
459 /* should only get here after delete_object was called */
460 WARN_ON(object->flags & OBJECT_ALLOCATED);
461
462 call_rcu(&object->rcu, free_object_rcu);
463}
464
465/*
466 * Look up an object in the prio search tree and increase its use_count.
467 */
468static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
469{
470 unsigned long flags;
471 struct kmemleak_object *object = NULL;
472
473 rcu_read_lock();
474 read_lock_irqsave(&kmemleak_lock, flags);
475 if (ptr >= min_addr && ptr < max_addr)
476 object = lookup_object(ptr, alias);
477 read_unlock_irqrestore(&kmemleak_lock, flags);
478
479 /* check whether the object is still available */
480 if (object && !get_object(object))
481 object = NULL;
482 rcu_read_unlock();
483
484 return object;
485}
486
487/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100488 * Save stack trace to the given array of MAX_TRACE size.
489 */
490static int __save_stack_trace(unsigned long *trace)
491{
492 struct stack_trace stack_trace;
493
494 stack_trace.max_entries = MAX_TRACE;
495 stack_trace.nr_entries = 0;
496 stack_trace.entries = trace;
497 stack_trace.skip = 2;
498 save_stack_trace(&stack_trace);
499
500 return stack_trace.nr_entries;
501}
502
503/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100504 * Create the metadata (struct kmemleak_object) corresponding to an allocated
505 * memory block and add it to the object_list and object_tree_root.
506 */
Catalin Marinasfd678962009-08-27 14:29:17 +0100507static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
508 int min_count, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100509{
510 unsigned long flags;
511 struct kmemleak_object *object;
512 struct prio_tree_node *node;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100513
Catalin Marinas216c04b2009-06-17 18:29:02 +0100514 object = kmem_cache_alloc(object_cache, gfp & GFP_KMEMLEAK_MASK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100515 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100516 kmemleak_stop("Cannot allocate a kmemleak_object structure\n");
Catalin Marinasfd678962009-08-27 14:29:17 +0100517 return NULL;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100518 }
519
520 INIT_LIST_HEAD(&object->object_list);
521 INIT_LIST_HEAD(&object->gray_list);
522 INIT_HLIST_HEAD(&object->area_list);
523 spin_lock_init(&object->lock);
524 atomic_set(&object->use_count, 1);
Catalin Marinas25873622009-07-07 10:32:58 +0100525 object->flags = OBJECT_ALLOCATED | OBJECT_NEW;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100526 object->pointer = ptr;
527 object->size = size;
528 object->min_count = min_count;
529 object->count = -1; /* no color initially */
530 object->jiffies = jiffies;
531
532 /* task information */
533 if (in_irq()) {
534 object->pid = 0;
535 strncpy(object->comm, "hardirq", sizeof(object->comm));
536 } else if (in_softirq()) {
537 object->pid = 0;
538 strncpy(object->comm, "softirq", sizeof(object->comm));
539 } else {
540 object->pid = current->pid;
541 /*
542 * There is a small chance of a race with set_task_comm(),
543 * however using get_task_comm() here may cause locking
544 * dependency issues with current->alloc_lock. In the worst
545 * case, the command line is not correct.
546 */
547 strncpy(object->comm, current->comm, sizeof(object->comm));
548 }
549
550 /* kernel backtrace */
Catalin Marinasfd678962009-08-27 14:29:17 +0100551 object->trace_len = __save_stack_trace(object->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100552
553 INIT_PRIO_TREE_NODE(&object->tree_node);
554 object->tree_node.start = ptr;
555 object->tree_node.last = ptr + size - 1;
556
557 write_lock_irqsave(&kmemleak_lock, flags);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100558
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100559 min_addr = min(min_addr, ptr);
560 max_addr = max(max_addr, ptr + size);
561 node = prio_tree_insert(&object_tree_root, &object->tree_node);
562 /*
563 * The code calling the kernel does not yet have the pointer to the
564 * memory block to be able to free it. However, we still hold the
565 * kmemleak_lock here in case parts of the kernel started freeing
566 * random memory blocks.
567 */
568 if (node != &object->tree_node) {
Joe Perchesae281062009-06-23 14:40:26 +0100569 kmemleak_stop("Cannot insert 0x%lx into the object search tree "
570 "(already existing)\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100571 object = lookup_object(ptr, 1);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100572 spin_lock(&object->lock);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100573 dump_object_info(object);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100574 spin_unlock(&object->lock);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100575
576 goto out;
577 }
578 list_add_tail_rcu(&object->object_list, &object_list);
579out:
580 write_unlock_irqrestore(&kmemleak_lock, flags);
Catalin Marinasfd678962009-08-27 14:29:17 +0100581 return object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100582}
583
584/*
585 * Remove the metadata (struct kmemleak_object) for a memory block from the
586 * object_list and object_tree_root and decrement its use_count.
587 */
Catalin Marinas53238a62009-07-07 10:33:00 +0100588static void __delete_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100589{
590 unsigned long flags;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100591
592 write_lock_irqsave(&kmemleak_lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100593 prio_tree_remove(&object_tree_root, &object->tree_node);
594 list_del_rcu(&object->object_list);
595 write_unlock_irqrestore(&kmemleak_lock, flags);
596
597 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
Catalin Marinas53238a62009-07-07 10:33:00 +0100598 WARN_ON(atomic_read(&object->use_count) < 2);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100599
600 /*
601 * Locking here also ensures that the corresponding memory block
602 * cannot be freed when it is being scanned.
603 */
604 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100605 object->flags &= ~OBJECT_ALLOCATED;
606 spin_unlock_irqrestore(&object->lock, flags);
607 put_object(object);
608}
609
610/*
Catalin Marinas53238a62009-07-07 10:33:00 +0100611 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
612 * delete it.
613 */
614static void delete_object_full(unsigned long ptr)
615{
616 struct kmemleak_object *object;
617
618 object = find_and_get_object(ptr, 0);
619 if (!object) {
620#ifdef DEBUG
621 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
622 ptr);
623#endif
624 return;
625 }
626 __delete_object(object);
627 put_object(object);
628}
629
630/*
631 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
632 * delete it. If the memory block is partially freed, the function may create
633 * additional metadata for the remaining parts of the block.
634 */
635static void delete_object_part(unsigned long ptr, size_t size)
636{
637 struct kmemleak_object *object;
638 unsigned long start, end;
639
640 object = find_and_get_object(ptr, 1);
641 if (!object) {
642#ifdef DEBUG
643 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
644 "(size %zu)\n", ptr, size);
645#endif
646 return;
647 }
648 __delete_object(object);
649
650 /*
651 * Create one or two objects that may result from the memory block
652 * split. Note that partial freeing is only done by free_bootmem() and
653 * this happens before kmemleak_init() is called. The path below is
654 * only executed during early log recording in kmemleak_init(), so
655 * GFP_KERNEL is enough.
656 */
657 start = object->pointer;
658 end = object->pointer + object->size;
659 if (ptr > start)
660 create_object(start, ptr - start, object->min_count,
661 GFP_KERNEL);
662 if (ptr + size < end)
663 create_object(ptr + size, end - ptr - size, object->min_count,
664 GFP_KERNEL);
665
666 put_object(object);
667}
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700668
669static void __paint_it(struct kmemleak_object *object, int color)
670{
671 object->min_count = color;
672 if (color == KMEMLEAK_BLACK)
673 object->flags |= OBJECT_NO_SCAN;
674}
675
676static void paint_it(struct kmemleak_object *object, int color)
677{
678 unsigned long flags;
679
680 spin_lock_irqsave(&object->lock, flags);
681 __paint_it(object, color);
682 spin_unlock_irqrestore(&object->lock, flags);
683}
684
685static void paint_ptr(unsigned long ptr, int color)
686{
687 struct kmemleak_object *object;
688
689 object = find_and_get_object(ptr, 0);
690 if (!object) {
691 kmemleak_warn("Trying to color unknown object "
692 "at 0x%08lx as %s\n", ptr,
693 (color == KMEMLEAK_GREY) ? "Grey" :
694 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
695 return;
696 }
697 paint_it(object, color);
698 put_object(object);
699}
700
Catalin Marinas53238a62009-07-07 10:33:00 +0100701/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100702 * Make a object permanently as gray-colored so that it can no longer be
703 * reported as a leak. This is used in general to mark a false positive.
704 */
705static void make_gray_object(unsigned long ptr)
706{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700707 paint_ptr(ptr, KMEMLEAK_GREY);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100708}
709
710/*
711 * Mark the object as black-colored so that it is ignored from scans and
712 * reporting.
713 */
714static void make_black_object(unsigned long ptr)
715{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700716 paint_ptr(ptr, KMEMLEAK_BLACK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100717}
718
719/*
720 * Add a scanning area to the object. If at least one such area is added,
721 * kmemleak will only scan these ranges rather than the whole memory block.
722 */
723static void add_scan_area(unsigned long ptr, unsigned long offset,
724 size_t length, gfp_t gfp)
725{
726 unsigned long flags;
727 struct kmemleak_object *object;
728 struct kmemleak_scan_area *area;
729
730 object = find_and_get_object(ptr, 0);
731 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100732 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
733 ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100734 return;
735 }
736
Catalin Marinas216c04b2009-06-17 18:29:02 +0100737 area = kmem_cache_alloc(scan_area_cache, gfp & GFP_KMEMLEAK_MASK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100738 if (!area) {
Joe Perchesae281062009-06-23 14:40:26 +0100739 kmemleak_warn("Cannot allocate a scan area\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100740 goto out;
741 }
742
743 spin_lock_irqsave(&object->lock, flags);
744 if (offset + length > object->size) {
Joe Perchesae281062009-06-23 14:40:26 +0100745 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100746 dump_object_info(object);
747 kmem_cache_free(scan_area_cache, area);
748 goto out_unlock;
749 }
750
751 INIT_HLIST_NODE(&area->node);
752 area->offset = offset;
753 area->length = length;
754
755 hlist_add_head(&area->node, &object->area_list);
756out_unlock:
757 spin_unlock_irqrestore(&object->lock, flags);
758out:
759 put_object(object);
760}
761
762/*
763 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
764 * pointer. Such object will not be scanned by kmemleak but references to it
765 * are searched.
766 */
767static void object_no_scan(unsigned long ptr)
768{
769 unsigned long flags;
770 struct kmemleak_object *object;
771
772 object = find_and_get_object(ptr, 0);
773 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100774 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100775 return;
776 }
777
778 spin_lock_irqsave(&object->lock, flags);
779 object->flags |= OBJECT_NO_SCAN;
780 spin_unlock_irqrestore(&object->lock, flags);
781 put_object(object);
782}
783
784/*
785 * Log an early kmemleak_* call to the early_log buffer. These calls will be
786 * processed later once kmemleak is fully initialized.
787 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100788static void __init log_early(int op_type, const void *ptr, size_t size,
789 int min_count, unsigned long offset, size_t length)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100790{
791 unsigned long flags;
792 struct early_log *log;
793
794 if (crt_early_log >= ARRAY_SIZE(early_log)) {
Catalin Marinasaddd72c2009-09-11 10:42:09 +0100795 pr_warning("Early log buffer exceeded, "
796 "please increase DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n");
Catalin Marinasa9d90582009-06-25 10:16:11 +0100797 kmemleak_disable();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100798 return;
799 }
800
801 /*
802 * There is no need for locking since the kernel is still in UP mode
803 * at this stage. Disabling the IRQs is enough.
804 */
805 local_irq_save(flags);
806 log = &early_log[crt_early_log];
807 log->op_type = op_type;
808 log->ptr = ptr;
809 log->size = size;
810 log->min_count = min_count;
811 log->offset = offset;
812 log->length = length;
Catalin Marinasfd678962009-08-27 14:29:17 +0100813 if (op_type == KMEMLEAK_ALLOC)
814 log->trace_len = __save_stack_trace(log->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100815 crt_early_log++;
816 local_irq_restore(flags);
817}
818
819/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100820 * Log an early allocated block and populate the stack trace.
821 */
822static void early_alloc(struct early_log *log)
823{
824 struct kmemleak_object *object;
825 unsigned long flags;
826 int i;
827
828 if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
829 return;
830
831 /*
832 * RCU locking needed to ensure object is not freed via put_object().
833 */
834 rcu_read_lock();
835 object = create_object((unsigned long)log->ptr, log->size,
Tetsuo Handac1bcd6b2009-10-09 10:39:24 +0100836 log->min_count, GFP_ATOMIC);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100837 if (!object)
838 goto out;
Catalin Marinasfd678962009-08-27 14:29:17 +0100839 spin_lock_irqsave(&object->lock, flags);
840 for (i = 0; i < log->trace_len; i++)
841 object->trace[i] = log->trace[i];
842 object->trace_len = log->trace_len;
843 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100844out:
Catalin Marinasfd678962009-08-27 14:29:17 +0100845 rcu_read_unlock();
846}
847
848/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100849 * Memory allocation function callback. This function is called from the
850 * kernel allocators when a new block is allocated (kmem_cache_alloc, kmalloc,
851 * vmalloc etc.).
852 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100853void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
854 gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100855{
856 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
857
858 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
859 create_object((unsigned long)ptr, size, min_count, gfp);
860 else if (atomic_read(&kmemleak_early_log))
861 log_early(KMEMLEAK_ALLOC, ptr, size, min_count, 0, 0);
862}
863EXPORT_SYMBOL_GPL(kmemleak_alloc);
864
865/*
866 * Memory freeing function callback. This function is called from the kernel
867 * allocators when a block is freed (kmem_cache_free, kfree, vfree etc.).
868 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100869void __ref kmemleak_free(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100870{
871 pr_debug("%s(0x%p)\n", __func__, ptr);
872
873 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinas53238a62009-07-07 10:33:00 +0100874 delete_object_full((unsigned long)ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100875 else if (atomic_read(&kmemleak_early_log))
876 log_early(KMEMLEAK_FREE, ptr, 0, 0, 0, 0);
877}
878EXPORT_SYMBOL_GPL(kmemleak_free);
879
880/*
Catalin Marinas53238a62009-07-07 10:33:00 +0100881 * Partial memory freeing function callback. This function is usually called
882 * from bootmem allocator when (part of) a memory block is freed.
883 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100884void __ref kmemleak_free_part(const void *ptr, size_t size)
Catalin Marinas53238a62009-07-07 10:33:00 +0100885{
886 pr_debug("%s(0x%p)\n", __func__, ptr);
887
888 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
889 delete_object_part((unsigned long)ptr, size);
890 else if (atomic_read(&kmemleak_early_log))
891 log_early(KMEMLEAK_FREE_PART, ptr, size, 0, 0, 0);
892}
893EXPORT_SYMBOL_GPL(kmemleak_free_part);
894
895/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100896 * Mark an already allocated memory block as a false positive. This will cause
897 * the block to no longer be reported as leak and always be scanned.
898 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100899void __ref kmemleak_not_leak(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100900{
901 pr_debug("%s(0x%p)\n", __func__, ptr);
902
903 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
904 make_gray_object((unsigned long)ptr);
905 else if (atomic_read(&kmemleak_early_log))
906 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0, 0, 0);
907}
908EXPORT_SYMBOL(kmemleak_not_leak);
909
910/*
911 * Ignore a memory block. This is usually done when it is known that the
912 * corresponding block is not a leak and does not contain any references to
913 * other allocated memory blocks.
914 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100915void __ref kmemleak_ignore(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100916{
917 pr_debug("%s(0x%p)\n", __func__, ptr);
918
919 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
920 make_black_object((unsigned long)ptr);
921 else if (atomic_read(&kmemleak_early_log))
922 log_early(KMEMLEAK_IGNORE, ptr, 0, 0, 0, 0);
923}
924EXPORT_SYMBOL(kmemleak_ignore);
925
926/*
927 * Limit the range to be scanned in an allocated memory block.
928 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100929void __ref kmemleak_scan_area(const void *ptr, unsigned long offset,
930 size_t length, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100931{
932 pr_debug("%s(0x%p)\n", __func__, ptr);
933
934 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
935 add_scan_area((unsigned long)ptr, offset, length, gfp);
936 else if (atomic_read(&kmemleak_early_log))
937 log_early(KMEMLEAK_SCAN_AREA, ptr, 0, 0, offset, length);
938}
939EXPORT_SYMBOL(kmemleak_scan_area);
940
941/*
942 * Inform kmemleak not to scan the given memory block.
943 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100944void __ref kmemleak_no_scan(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100945{
946 pr_debug("%s(0x%p)\n", __func__, ptr);
947
948 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
949 object_no_scan((unsigned long)ptr);
950 else if (atomic_read(&kmemleak_early_log))
951 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0, 0, 0);
952}
953EXPORT_SYMBOL(kmemleak_no_scan);
954
955/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100956 * Memory scanning is a long process and it needs to be interruptable. This
957 * function checks whether such interrupt condition occured.
958 */
959static int scan_should_stop(void)
960{
961 if (!atomic_read(&kmemleak_enabled))
962 return 1;
963
964 /*
965 * This function may be called from either process or kthread context,
966 * hence the need to check for both stop conditions.
967 */
968 if (current->mm)
969 return signal_pending(current);
970 else
971 return kthread_should_stop();
972
973 return 0;
974}
975
976/*
977 * Scan a memory block (exclusive range) for valid pointers and add those
978 * found to the gray list.
979 */
980static void scan_block(void *_start, void *_end,
Catalin Marinas4b8a9672009-07-07 10:32:56 +0100981 struct kmemleak_object *scanned, int allow_resched)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100982{
983 unsigned long *ptr;
984 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
985 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
986
987 for (ptr = start; ptr < end; ptr++) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100988 struct kmemleak_object *object;
Pekka Enberg8e019362009-08-27 14:50:00 +0100989 unsigned long flags;
990 unsigned long pointer;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100991
Catalin Marinas4b8a9672009-07-07 10:32:56 +0100992 if (allow_resched)
993 cond_resched();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100994 if (scan_should_stop())
995 break;
996
Pekka Enberg8e019362009-08-27 14:50:00 +0100997 /* don't scan uninitialized memory */
998 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
999 BYTES_PER_POINTER))
1000 continue;
1001
1002 pointer = *ptr;
1003
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001004 object = find_and_get_object(pointer, 1);
1005 if (!object)
1006 continue;
1007 if (object == scanned) {
1008 /* self referenced, ignore */
1009 put_object(object);
1010 continue;
1011 }
1012
1013 /*
1014 * Avoid the lockdep recursive warning on object->lock being
1015 * previously acquired in scan_object(). These locks are
1016 * enclosed by scan_mutex.
1017 */
1018 spin_lock_irqsave_nested(&object->lock, flags,
1019 SINGLE_DEPTH_NESTING);
1020 if (!color_white(object)) {
1021 /* non-orphan, ignored or new */
1022 spin_unlock_irqrestore(&object->lock, flags);
1023 put_object(object);
1024 continue;
1025 }
1026
1027 /*
1028 * Increase the object's reference count (number of pointers
1029 * to the memory block). If this count reaches the required
1030 * minimum, the object's color will become gray and it will be
1031 * added to the gray_list.
1032 */
1033 object->count++;
1034 if (color_gray(object))
1035 list_add_tail(&object->gray_list, &gray_list);
1036 else
1037 put_object(object);
1038 spin_unlock_irqrestore(&object->lock, flags);
1039 }
1040}
1041
1042/*
1043 * Scan a memory block corresponding to a kmemleak_object. A condition is
1044 * that object->use_count >= 1.
1045 */
1046static void scan_object(struct kmemleak_object *object)
1047{
1048 struct kmemleak_scan_area *area;
1049 struct hlist_node *elem;
1050 unsigned long flags;
1051
1052 /*
Uwe Kleine-König21ae2952009-10-07 15:21:09 +02001053 * Once the object->lock is acquired, the corresponding memory block
1054 * cannot be freed (the same lock is acquired in delete_object).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001055 */
1056 spin_lock_irqsave(&object->lock, flags);
1057 if (object->flags & OBJECT_NO_SCAN)
1058 goto out;
1059 if (!(object->flags & OBJECT_ALLOCATED))
1060 /* already freed object */
1061 goto out;
Catalin Marinasaf986032009-08-27 14:29:12 +01001062 if (hlist_empty(&object->area_list)) {
1063 void *start = (void *)object->pointer;
1064 void *end = (void *)(object->pointer + object->size);
1065
1066 while (start < end && (object->flags & OBJECT_ALLOCATED) &&
1067 !(object->flags & OBJECT_NO_SCAN)) {
1068 scan_block(start, min(start + MAX_SCAN_SIZE, end),
1069 object, 0);
1070 start += MAX_SCAN_SIZE;
1071
1072 spin_unlock_irqrestore(&object->lock, flags);
1073 cond_resched();
1074 spin_lock_irqsave(&object->lock, flags);
1075 }
1076 } else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001077 hlist_for_each_entry(area, elem, &object->area_list, node)
1078 scan_block((void *)(object->pointer + area->offset),
1079 (void *)(object->pointer + area->offset
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001080 + area->length), object, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001081out:
1082 spin_unlock_irqrestore(&object->lock, flags);
1083}
1084
1085/*
1086 * Scan data sections and all the referenced memory blocks allocated via the
1087 * kernel's standard allocators. This function must be called with the
1088 * scan_mutex held.
1089 */
1090static void kmemleak_scan(void)
1091{
1092 unsigned long flags;
1093 struct kmemleak_object *object, *tmp;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001094 int i;
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001095 int new_leaks = 0;
Catalin Marinas25873622009-07-07 10:32:58 +01001096 int gray_list_pass = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001097
Catalin Marinasacf49682009-06-26 17:38:29 +01001098 jiffies_last_scan = jiffies;
1099
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001100 /* prepare the kmemleak_object's */
1101 rcu_read_lock();
1102 list_for_each_entry_rcu(object, &object_list, object_list) {
1103 spin_lock_irqsave(&object->lock, flags);
1104#ifdef DEBUG
1105 /*
1106 * With a few exceptions there should be a maximum of
1107 * 1 reference to any object at this point.
1108 */
1109 if (atomic_read(&object->use_count) > 1) {
Joe Perchesae281062009-06-23 14:40:26 +01001110 pr_debug("object->use_count = %d\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001111 atomic_read(&object->use_count));
1112 dump_object_info(object);
1113 }
1114#endif
1115 /* reset the reference count (whiten the object) */
1116 object->count = 0;
Catalin Marinas25873622009-07-07 10:32:58 +01001117 object->flags &= ~OBJECT_NEW;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001118 if (color_gray(object) && get_object(object))
1119 list_add_tail(&object->gray_list, &gray_list);
1120
1121 spin_unlock_irqrestore(&object->lock, flags);
1122 }
1123 rcu_read_unlock();
1124
1125 /* data/bss scanning */
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001126 scan_block(_sdata, _edata, NULL, 1);
1127 scan_block(__bss_start, __bss_stop, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001128
1129#ifdef CONFIG_SMP
1130 /* per-cpu sections scanning */
1131 for_each_possible_cpu(i)
1132 scan_block(__per_cpu_start + per_cpu_offset(i),
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001133 __per_cpu_end + per_cpu_offset(i), NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001134#endif
1135
1136 /*
1137 * Struct page scanning for each node. The code below is not yet safe
1138 * with MEMORY_HOTPLUG.
1139 */
1140 for_each_online_node(i) {
1141 pg_data_t *pgdat = NODE_DATA(i);
1142 unsigned long start_pfn = pgdat->node_start_pfn;
1143 unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
1144 unsigned long pfn;
1145
1146 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1147 struct page *page;
1148
1149 if (!pfn_valid(pfn))
1150 continue;
1151 page = pfn_to_page(pfn);
1152 /* only scan if page is in use */
1153 if (page_count(page) == 0)
1154 continue;
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001155 scan_block(page, page + 1, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001156 }
1157 }
1158
1159 /*
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001160 * Scanning the task stacks (may introduce false negatives).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001161 */
1162 if (kmemleak_stack_scan) {
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001163 struct task_struct *p, *g;
1164
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001165 read_lock(&tasklist_lock);
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001166 do_each_thread(g, p) {
1167 scan_block(task_stack_page(p), task_stack_page(p) +
1168 THREAD_SIZE, NULL, 0);
1169 } while_each_thread(g, p);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001170 read_unlock(&tasklist_lock);
1171 }
1172
1173 /*
1174 * Scan the objects already referenced from the sections scanned
1175 * above. More objects will be referenced and, if there are no memory
1176 * leaks, all the objects will be scanned. The list traversal is safe
1177 * for both tail additions and removals from inside the loop. The
1178 * kmemleak objects cannot be freed from outside the loop because their
1179 * use_count was increased.
1180 */
Catalin Marinas25873622009-07-07 10:32:58 +01001181repeat:
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001182 object = list_entry(gray_list.next, typeof(*object), gray_list);
1183 while (&object->gray_list != &gray_list) {
Ingo Molnar57d81f62009-07-01 09:43:53 +02001184 cond_resched();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001185
1186 /* may add new objects to the list */
1187 if (!scan_should_stop())
1188 scan_object(object);
1189
1190 tmp = list_entry(object->gray_list.next, typeof(*object),
1191 gray_list);
1192
1193 /* remove the object from the list and release it */
1194 list_del(&object->gray_list);
1195 put_object(object);
1196
1197 object = tmp;
1198 }
Catalin Marinas25873622009-07-07 10:32:58 +01001199
1200 if (scan_should_stop() || ++gray_list_pass >= GRAY_LIST_PASSES)
1201 goto scan_end;
1202
1203 /*
1204 * Check for new objects allocated during this scanning and add them
1205 * to the gray list.
1206 */
1207 rcu_read_lock();
1208 list_for_each_entry_rcu(object, &object_list, object_list) {
1209 spin_lock_irqsave(&object->lock, flags);
1210 if ((object->flags & OBJECT_NEW) && !color_black(object) &&
1211 get_object(object)) {
1212 object->flags &= ~OBJECT_NEW;
1213 list_add_tail(&object->gray_list, &gray_list);
1214 }
1215 spin_unlock_irqrestore(&object->lock, flags);
1216 }
1217 rcu_read_unlock();
1218
1219 if (!list_empty(&gray_list))
1220 goto repeat;
1221
1222scan_end:
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001223 WARN_ON(!list_empty(&gray_list));
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001224
1225 /*
Catalin Marinas25873622009-07-07 10:32:58 +01001226 * If scanning was stopped or new objects were being allocated at a
1227 * higher rate than gray list scanning, do not report any new
1228 * unreferenced objects.
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001229 */
Catalin Marinas25873622009-07-07 10:32:58 +01001230 if (scan_should_stop() || gray_list_pass >= GRAY_LIST_PASSES)
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001231 return;
1232
1233 /*
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001234 * Scanning result reporting.
1235 */
1236 rcu_read_lock();
1237 list_for_each_entry_rcu(object, &object_list, object_list) {
1238 spin_lock_irqsave(&object->lock, flags);
1239 if (unreferenced_object(object) &&
1240 !(object->flags & OBJECT_REPORTED)) {
1241 object->flags |= OBJECT_REPORTED;
1242 new_leaks++;
1243 }
1244 spin_unlock_irqrestore(&object->lock, flags);
1245 }
1246 rcu_read_unlock();
1247
1248 if (new_leaks)
1249 pr_info("%d new suspected memory leaks (see "
1250 "/sys/kernel/debug/kmemleak)\n", new_leaks);
1251
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001252}
1253
1254/*
1255 * Thread function performing automatic memory scanning. Unreferenced objects
1256 * at the end of a memory scan are reported but only the first time.
1257 */
1258static int kmemleak_scan_thread(void *arg)
1259{
1260 static int first_run = 1;
1261
Joe Perchesae281062009-06-23 14:40:26 +01001262 pr_info("Automatic memory scanning thread started\n");
Catalin Marinasbf2a76b2009-07-07 10:32:55 +01001263 set_user_nice(current, 10);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001264
1265 /*
1266 * Wait before the first scan to allow the system to fully initialize.
1267 */
1268 if (first_run) {
1269 first_run = 0;
1270 ssleep(SECS_FIRST_SCAN);
1271 }
1272
1273 while (!kthread_should_stop()) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001274 signed long timeout = jiffies_scan_wait;
1275
1276 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001277 kmemleak_scan();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001278 mutex_unlock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001279
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001280 /* wait before the next scan */
1281 while (timeout && !kthread_should_stop())
1282 timeout = schedule_timeout_interruptible(timeout);
1283 }
1284
Joe Perchesae281062009-06-23 14:40:26 +01001285 pr_info("Automatic memory scanning thread ended\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001286
1287 return 0;
1288}
1289
1290/*
1291 * Start the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001292 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001293 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001294static void start_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001295{
1296 if (scan_thread)
1297 return;
1298 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1299 if (IS_ERR(scan_thread)) {
Joe Perchesae281062009-06-23 14:40:26 +01001300 pr_warning("Failed to create the scan thread\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001301 scan_thread = NULL;
1302 }
1303}
1304
1305/*
1306 * Stop the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001307 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001308 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001309static void stop_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001310{
1311 if (scan_thread) {
1312 kthread_stop(scan_thread);
1313 scan_thread = NULL;
1314 }
1315}
1316
1317/*
1318 * Iterate over the object_list and return the first valid object at or after
1319 * the required position with its use_count incremented. The function triggers
1320 * a memory scanning when the pos argument points to the first position.
1321 */
1322static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1323{
1324 struct kmemleak_object *object;
1325 loff_t n = *pos;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001326 int err;
1327
1328 err = mutex_lock_interruptible(&scan_mutex);
1329 if (err < 0)
1330 return ERR_PTR(err);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001331
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001332 rcu_read_lock();
1333 list_for_each_entry_rcu(object, &object_list, object_list) {
1334 if (n-- > 0)
1335 continue;
1336 if (get_object(object))
1337 goto out;
1338 }
1339 object = NULL;
1340out:
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001341 return object;
1342}
1343
1344/*
1345 * Return the next object in the object_list. The function decrements the
1346 * use_count of the previous object and increases that of the next one.
1347 */
1348static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1349{
1350 struct kmemleak_object *prev_obj = v;
1351 struct kmemleak_object *next_obj = NULL;
1352 struct list_head *n = &prev_obj->object_list;
1353
1354 ++(*pos);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001355
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001356 list_for_each_continue_rcu(n, &object_list) {
1357 next_obj = list_entry(n, struct kmemleak_object, object_list);
1358 if (get_object(next_obj))
1359 break;
1360 }
Catalin Marinas288c8572009-07-07 10:32:57 +01001361
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001362 put_object(prev_obj);
1363 return next_obj;
1364}
1365
1366/*
1367 * Decrement the use_count of the last object required, if any.
1368 */
1369static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1370{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001371 if (!IS_ERR(v)) {
1372 /*
1373 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1374 * waiting was interrupted, so only release it if !IS_ERR.
1375 */
Catalin Marinasf5886c72009-07-29 16:26:57 +01001376 rcu_read_unlock();
Catalin Marinasb87324d2009-07-07 10:32:58 +01001377 mutex_unlock(&scan_mutex);
1378 if (v)
1379 put_object(v);
1380 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001381}
1382
1383/*
1384 * Print the information for an unreferenced object to the seq file.
1385 */
1386static int kmemleak_seq_show(struct seq_file *seq, void *v)
1387{
1388 struct kmemleak_object *object = v;
1389 unsigned long flags;
1390
1391 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas288c8572009-07-07 10:32:57 +01001392 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001393 print_unreferenced(seq, object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001394 spin_unlock_irqrestore(&object->lock, flags);
1395 return 0;
1396}
1397
1398static const struct seq_operations kmemleak_seq_ops = {
1399 .start = kmemleak_seq_start,
1400 .next = kmemleak_seq_next,
1401 .stop = kmemleak_seq_stop,
1402 .show = kmemleak_seq_show,
1403};
1404
1405static int kmemleak_open(struct inode *inode, struct file *file)
1406{
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001407 if (!atomic_read(&kmemleak_enabled))
1408 return -EBUSY;
1409
Catalin Marinasb87324d2009-07-07 10:32:58 +01001410 return seq_open(file, &kmemleak_seq_ops);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001411}
1412
1413static int kmemleak_release(struct inode *inode, struct file *file)
1414{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001415 return seq_release(inode, file);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001416}
1417
Catalin Marinas189d84e2009-08-27 14:29:15 +01001418static int dump_str_object_info(const char *str)
1419{
1420 unsigned long flags;
1421 struct kmemleak_object *object;
1422 unsigned long addr;
1423
1424 addr= simple_strtoul(str, NULL, 0);
1425 object = find_and_get_object(addr, 0);
1426 if (!object) {
1427 pr_info("Unknown object at 0x%08lx\n", addr);
1428 return -EINVAL;
1429 }
1430
1431 spin_lock_irqsave(&object->lock, flags);
1432 dump_object_info(object);
1433 spin_unlock_irqrestore(&object->lock, flags);
1434
1435 put_object(object);
1436 return 0;
1437}
1438
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001439/*
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001440 * We use grey instead of black to ensure we can do future scans on the same
1441 * objects. If we did not do future scans these black objects could
1442 * potentially contain references to newly allocated objects in the future and
1443 * we'd end up with false positives.
1444 */
1445static void kmemleak_clear(void)
1446{
1447 struct kmemleak_object *object;
1448 unsigned long flags;
1449
1450 rcu_read_lock();
1451 list_for_each_entry_rcu(object, &object_list, object_list) {
1452 spin_lock_irqsave(&object->lock, flags);
1453 if ((object->flags & OBJECT_REPORTED) &&
1454 unreferenced_object(object))
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -07001455 __paint_it(object, KMEMLEAK_GREY);
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001456 spin_unlock_irqrestore(&object->lock, flags);
1457 }
1458 rcu_read_unlock();
1459}
1460
1461/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001462 * File write operation to configure kmemleak at run-time. The following
1463 * commands can be written to the /sys/kernel/debug/kmemleak file:
1464 * off - disable kmemleak (irreversible)
1465 * stack=on - enable the task stacks scanning
1466 * stack=off - disable the tasks stacks scanning
1467 * scan=on - start the automatic memory scanning thread
1468 * scan=off - stop the automatic memory scanning thread
1469 * scan=... - set the automatic memory scanning period in seconds (0 to
1470 * disable it)
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001471 * scan - trigger a memory scan
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001472 * clear - mark all current reported unreferenced kmemleak objects as
1473 * grey to ignore printing them
Catalin Marinas189d84e2009-08-27 14:29:15 +01001474 * dump=... - dump information about the object found at the given address
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001475 */
1476static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1477 size_t size, loff_t *ppos)
1478{
1479 char buf[64];
1480 int buf_size;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001481 int ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001482
1483 buf_size = min(size, (sizeof(buf) - 1));
1484 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1485 return -EFAULT;
1486 buf[buf_size] = 0;
1487
Catalin Marinasb87324d2009-07-07 10:32:58 +01001488 ret = mutex_lock_interruptible(&scan_mutex);
1489 if (ret < 0)
1490 return ret;
1491
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001492 if (strncmp(buf, "off", 3) == 0)
1493 kmemleak_disable();
1494 else if (strncmp(buf, "stack=on", 8) == 0)
1495 kmemleak_stack_scan = 1;
1496 else if (strncmp(buf, "stack=off", 9) == 0)
1497 kmemleak_stack_scan = 0;
1498 else if (strncmp(buf, "scan=on", 7) == 0)
1499 start_scan_thread();
1500 else if (strncmp(buf, "scan=off", 8) == 0)
1501 stop_scan_thread();
1502 else if (strncmp(buf, "scan=", 5) == 0) {
1503 unsigned long secs;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001504
Catalin Marinasb87324d2009-07-07 10:32:58 +01001505 ret = strict_strtoul(buf + 5, 0, &secs);
1506 if (ret < 0)
1507 goto out;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001508 stop_scan_thread();
1509 if (secs) {
1510 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1511 start_scan_thread();
1512 }
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001513 } else if (strncmp(buf, "scan", 4) == 0)
1514 kmemleak_scan();
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001515 else if (strncmp(buf, "clear", 5) == 0)
1516 kmemleak_clear();
Catalin Marinas189d84e2009-08-27 14:29:15 +01001517 else if (strncmp(buf, "dump=", 5) == 0)
1518 ret = dump_str_object_info(buf + 5);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001519 else
Catalin Marinasb87324d2009-07-07 10:32:58 +01001520 ret = -EINVAL;
1521
1522out:
1523 mutex_unlock(&scan_mutex);
1524 if (ret < 0)
1525 return ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001526
1527 /* ignore the rest of the buffer, only one command at a time */
1528 *ppos += size;
1529 return size;
1530}
1531
1532static const struct file_operations kmemleak_fops = {
1533 .owner = THIS_MODULE,
1534 .open = kmemleak_open,
1535 .read = seq_read,
1536 .write = kmemleak_write,
1537 .llseek = seq_lseek,
1538 .release = kmemleak_release,
1539};
1540
1541/*
1542 * Perform the freeing of the kmemleak internal objects after waiting for any
1543 * current memory scan to complete.
1544 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001545static void kmemleak_do_cleanup(struct work_struct *work)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001546{
1547 struct kmemleak_object *object;
1548
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001549 mutex_lock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001550 stop_scan_thread();
1551
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001552 rcu_read_lock();
1553 list_for_each_entry_rcu(object, &object_list, object_list)
Catalin Marinas53238a62009-07-07 10:33:00 +01001554 delete_object_full(object->pointer);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001555 rcu_read_unlock();
1556 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001557}
1558
Catalin Marinas179a8102009-09-07 10:14:42 +01001559static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001560
1561/*
1562 * Disable kmemleak. No memory allocation/freeing will be traced once this
1563 * function is called. Disabling kmemleak is an irreversible operation.
1564 */
1565static void kmemleak_disable(void)
1566{
1567 /* atomically check whether it was already invoked */
1568 if (atomic_cmpxchg(&kmemleak_error, 0, 1))
1569 return;
1570
1571 /* stop any memory operation tracing */
1572 atomic_set(&kmemleak_early_log, 0);
1573 atomic_set(&kmemleak_enabled, 0);
1574
1575 /* check whether it is too early for a kernel thread */
1576 if (atomic_read(&kmemleak_initialized))
Catalin Marinas179a8102009-09-07 10:14:42 +01001577 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001578
1579 pr_info("Kernel memory leak detector disabled\n");
1580}
1581
1582/*
1583 * Allow boot-time kmemleak disabling (enabled by default).
1584 */
1585static int kmemleak_boot_config(char *str)
1586{
1587 if (!str)
1588 return -EINVAL;
1589 if (strcmp(str, "off") == 0)
1590 kmemleak_disable();
1591 else if (strcmp(str, "on") != 0)
1592 return -EINVAL;
1593 return 0;
1594}
1595early_param("kmemleak", kmemleak_boot_config);
1596
1597/*
Catalin Marinas20301172009-06-17 18:29:04 +01001598 * Kmemleak initialization.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001599 */
1600void __init kmemleak_init(void)
1601{
1602 int i;
1603 unsigned long flags;
1604
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001605 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1606 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1607
1608 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1609 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
1610 INIT_PRIO_TREE_ROOT(&object_tree_root);
1611
1612 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1613 local_irq_save(flags);
1614 if (!atomic_read(&kmemleak_error)) {
1615 atomic_set(&kmemleak_enabled, 1);
1616 atomic_set(&kmemleak_early_log, 0);
1617 }
1618 local_irq_restore(flags);
1619
1620 /*
1621 * This is the point where tracking allocations is safe. Automatic
1622 * scanning is started during the late initcall. Add the early logged
1623 * callbacks to the kmemleak infrastructure.
1624 */
1625 for (i = 0; i < crt_early_log; i++) {
1626 struct early_log *log = &early_log[i];
1627
1628 switch (log->op_type) {
1629 case KMEMLEAK_ALLOC:
Catalin Marinasfd678962009-08-27 14:29:17 +01001630 early_alloc(log);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001631 break;
1632 case KMEMLEAK_FREE:
1633 kmemleak_free(log->ptr);
1634 break;
Catalin Marinas53238a62009-07-07 10:33:00 +01001635 case KMEMLEAK_FREE_PART:
1636 kmemleak_free_part(log->ptr, log->size);
1637 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001638 case KMEMLEAK_NOT_LEAK:
1639 kmemleak_not_leak(log->ptr);
1640 break;
1641 case KMEMLEAK_IGNORE:
1642 kmemleak_ignore(log->ptr);
1643 break;
1644 case KMEMLEAK_SCAN_AREA:
1645 kmemleak_scan_area(log->ptr, log->offset, log->length,
1646 GFP_KERNEL);
1647 break;
1648 case KMEMLEAK_NO_SCAN:
1649 kmemleak_no_scan(log->ptr);
1650 break;
1651 default:
1652 WARN_ON(1);
1653 }
1654 }
1655}
1656
1657/*
1658 * Late initialization function.
1659 */
1660static int __init kmemleak_late_init(void)
1661{
1662 struct dentry *dentry;
1663
1664 atomic_set(&kmemleak_initialized, 1);
1665
1666 if (atomic_read(&kmemleak_error)) {
1667 /*
1668 * Some error occured and kmemleak was disabled. There is a
1669 * small chance that kmemleak_disable() was called immediately
1670 * after setting kmemleak_initialized and we may end up with
1671 * two clean-up threads but serialized by scan_mutex.
1672 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001673 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001674 return -ENOMEM;
1675 }
1676
1677 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1678 &kmemleak_fops);
1679 if (!dentry)
Joe Perchesae281062009-06-23 14:40:26 +01001680 pr_warning("Failed to create the debugfs kmemleak file\n");
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001681 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001682 start_scan_thread();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001683 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001684
1685 pr_info("Kernel memory leak detector initialized\n");
1686
1687 return 0;
1688}
1689late_initcall(kmemleak_late_init);