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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
Michel Lespinasse85d3a312012-10-08 16:31:27 -070032 * blocks. The object_tree_root is a red black tree used to look-up
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010033 * 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>
Paul Gortmakerb95f1b312011-10-16 02:01:52 -040072#include <linux/export.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010073#include <linux/kthread.h>
Michel Lespinasse85d3a312012-10-08 16:31:27 -070074#include <linux/rbtree.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010075#include <linux/fs.h>
76#include <linux/debugfs.h>
77#include <linux/seq_file.h>
78#include <linux/cpumask.h>
79#include <linux/spinlock.h>
80#include <linux/mutex.h>
81#include <linux/rcupdate.h>
82#include <linux/stacktrace.h>
83#include <linux/cache.h>
84#include <linux/percpu.h>
85#include <linux/hardirq.h>
86#include <linux/mmzone.h>
87#include <linux/slab.h>
88#include <linux/thread_info.h>
89#include <linux/err.h>
90#include <linux/uaccess.h>
91#include <linux/string.h>
92#include <linux/nodemask.h>
93#include <linux/mm.h>
Catalin Marinas179a8102009-09-07 10:14:42 +010094#include <linux/workqueue.h>
Catalin Marinas04609ccc2009-10-28 13:33:12 +000095#include <linux/crc32.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +010096
97#include <asm/sections.h>
98#include <asm/processor.h>
Arun Sharma600634972011-07-26 16:09:06 -070099#include <linux/atomic.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100100
Pekka Enberg8e019362009-08-27 14:50:00 +0100101#include <linux/kmemcheck.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100102#include <linux/kmemleak.h>
Laura Abbott029aeff2011-11-15 23:49:09 +0000103#include <linux/memory_hotplug.h>
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100104
105/*
106 * Kmemleak configuration and common defines.
107 */
108#define MAX_TRACE 16 /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100109#define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100110#define SECS_FIRST_SCAN 60 /* delay before the first scan */
111#define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
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 */
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000117#define gfp_kmemleak_mask(gfp) (((gfp) & (GFP_KERNEL | GFP_ATOMIC)) | \
118 __GFP_NORETRY | __GFP_NOMEMALLOC | \
119 __GFP_NOWARN)
Catalin Marinas216c04b2009-06-17 18:29:02 +0100120
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100121/* scanning area inside a memory block */
122struct kmemleak_scan_area {
123 struct hlist_node node;
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000124 unsigned long start;
125 size_t size;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100126};
127
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700128#define KMEMLEAK_GREY 0
129#define KMEMLEAK_BLACK -1
130
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100131/*
132 * Structure holding the metadata for each allocated memory block.
133 * Modifications to such objects should be made while holding the
134 * object->lock. Insertions or deletions from object_list, gray_list or
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700135 * rb_node are already protected by the corresponding locks or mutex (see
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100136 * the notes on locking above). These objects are reference-counted
137 * (use_count) and freed using the RCU mechanism.
138 */
139struct kmemleak_object {
140 spinlock_t lock;
141 unsigned long flags; /* object status flags */
142 struct list_head object_list;
143 struct list_head gray_list;
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700144 struct rb_node rb_node;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100145 struct rcu_head rcu; /* object_list lockless traversal */
146 /* object usage count; object freed when use_count == 0 */
147 atomic_t use_count;
148 unsigned long pointer;
149 size_t size;
150 /* minimum number of a pointers found before it is considered leak */
151 int min_count;
152 /* the total number of pointers found pointing to this object */
153 int count;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000154 /* checksum for detecting modified objects */
155 u32 checksum;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100156 /* memory ranges to be scanned inside an object (empty for all) */
157 struct hlist_head area_list;
158 unsigned long trace[MAX_TRACE];
159 unsigned int trace_len;
160 unsigned long jiffies; /* creation timestamp */
161 pid_t pid; /* pid of the current task */
162 char comm[TASK_COMM_LEN]; /* executable name */
163};
164
165/* flag representing the memory block allocation status */
166#define OBJECT_ALLOCATED (1 << 0)
167/* flag set after the first reporting of an unreference object */
168#define OBJECT_REPORTED (1 << 1)
169/* flag set to not scan the object */
170#define OBJECT_NO_SCAN (1 << 2)
171
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100172/* number of bytes to print per line; must be 16 or 32 */
173#define HEX_ROW_SIZE 16
174/* number of bytes to print at a time (1, 2, 4, 8) */
175#define HEX_GROUP_SIZE 1
176/* include ASCII after the hex output */
177#define HEX_ASCII 1
178/* max number of lines to be printed */
179#define HEX_MAX_LINES 2
180
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100181/* the list of all allocated objects */
182static LIST_HEAD(object_list);
183/* the list of gray-colored objects (see color_gray comment below) */
184static LIST_HEAD(gray_list);
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700185/* search tree for object boundaries */
186static struct rb_root object_tree_root = RB_ROOT;
187/* rw_lock protecting the access to object_list and object_tree_root */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100188static DEFINE_RWLOCK(kmemleak_lock);
189
190/* allocation caches for kmemleak internal data */
191static struct kmem_cache *object_cache;
192static struct kmem_cache *scan_area_cache;
193
194/* set if tracing memory operations is enabled */
195static atomic_t kmemleak_enabled = ATOMIC_INIT(0);
196/* set in the late_initcall if there were no errors */
197static atomic_t kmemleak_initialized = ATOMIC_INIT(0);
198/* enables or disables early logging of the memory operations */
199static atomic_t kmemleak_early_log = ATOMIC_INIT(1);
Catalin Marinas5f790202011-09-28 12:17:03 +0100200/* set if a kmemleak warning was issued */
201static atomic_t kmemleak_warning = ATOMIC_INIT(0);
202/* set if a fatal kmemleak error has occurred */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100203static atomic_t kmemleak_error = ATOMIC_INIT(0);
204
205/* minimum and maximum address that may be valid pointers */
206static unsigned long min_addr = ULONG_MAX;
207static unsigned long max_addr;
208
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100209static struct task_struct *scan_thread;
Catalin Marinasacf49682009-06-26 17:38:29 +0100210/* used to avoid reporting of recently allocated objects */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100211static unsigned long jiffies_min_age;
Catalin Marinasacf49682009-06-26 17:38:29 +0100212static unsigned long jiffies_last_scan;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100213/* delay between automatic memory scannings */
214static signed long jiffies_scan_wait;
215/* enables or disables the task stacks scanning */
Catalin Marinase0a2a162009-06-26 17:38:25 +0100216static int kmemleak_stack_scan = 1;
Catalin Marinas4698c1f2009-06-26 17:38:27 +0100217/* protects the memory scanning, parameters and debug/kmemleak file access */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100218static DEFINE_MUTEX(scan_mutex);
Jason Baronab0155a2010-07-19 11:54:17 +0100219/* setting kmemleak=on, will set this var, skipping the disable */
220static int kmemleak_skip_disable;
Li Zefandc9b3f42014-04-03 14:46:26 -0700221/* If there are leaks that can be reported */
222static bool kmemleak_found_leaks;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100223
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100224/*
Catalin Marinas20301172009-06-17 18:29:04 +0100225 * Early object allocation/freeing logging. Kmemleak is initialized after the
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100226 * kernel allocator. However, both the kernel allocator and kmemleak may
Catalin Marinas20301172009-06-17 18:29:04 +0100227 * allocate memory blocks which need to be tracked. Kmemleak defines an
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100228 * arbitrary buffer to hold the allocation/freeing information before it is
229 * fully initialized.
230 */
231
232/* kmemleak operation type for early logging */
233enum {
234 KMEMLEAK_ALLOC,
Catalin Marinasf528f0b2011-09-26 17:12:53 +0100235 KMEMLEAK_ALLOC_PERCPU,
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100236 KMEMLEAK_FREE,
Catalin Marinas53238a62009-07-07 10:33:00 +0100237 KMEMLEAK_FREE_PART,
Catalin Marinasf528f0b2011-09-26 17:12:53 +0100238 KMEMLEAK_FREE_PERCPU,
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100239 KMEMLEAK_NOT_LEAK,
240 KMEMLEAK_IGNORE,
241 KMEMLEAK_SCAN_AREA,
242 KMEMLEAK_NO_SCAN
243};
244
245/*
246 * Structure holding the information passed to kmemleak callbacks during the
247 * early logging.
248 */
249struct early_log {
250 int op_type; /* kmemleak operation type */
251 const void *ptr; /* allocated/freed memory block */
252 size_t size; /* memory block size */
253 int min_count; /* minimum reference count */
Catalin Marinasfd678962009-08-27 14:29:17 +0100254 unsigned long trace[MAX_TRACE]; /* stack trace */
255 unsigned int trace_len; /* stack trace length */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100256};
257
258/* early logging buffer and current position */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100259static struct early_log
260 early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE] __initdata;
261static int crt_early_log __initdata;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100262
263static void kmemleak_disable(void);
264
265/*
266 * Print a warning and dump the stack trace.
267 */
Catalin Marinas5f790202011-09-28 12:17:03 +0100268#define kmemleak_warn(x...) do { \
269 pr_warning(x); \
270 dump_stack(); \
271 atomic_set(&kmemleak_warning, 1); \
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100272} while (0)
273
274/*
Lucas De Marchi25985ed2011-03-30 22:57:33 -0300275 * Macro invoked when a serious kmemleak condition occurred and cannot be
Catalin Marinas20301172009-06-17 18:29:04 +0100276 * recovered from. Kmemleak will be disabled and further allocation/freeing
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100277 * tracing no longer available.
278 */
Catalin Marinas000814f2009-06-17 18:29:03 +0100279#define kmemleak_stop(x...) do { \
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100280 kmemleak_warn(x); \
281 kmemleak_disable(); \
282} while (0)
283
284/*
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100285 * Printing of the objects hex dump to the seq file. The number of lines to be
286 * printed is limited to HEX_MAX_LINES to prevent seq file spamming. The
287 * actual number of printed bytes depends on HEX_ROW_SIZE. It must be called
288 * with the object->lock held.
289 */
290static void hex_dump_object(struct seq_file *seq,
291 struct kmemleak_object *object)
292{
293 const u8 *ptr = (const u8 *)object->pointer;
294 int i, len, remaining;
295 unsigned char linebuf[HEX_ROW_SIZE * 5];
296
297 /* limit the number of lines to HEX_MAX_LINES */
298 remaining = len =
299 min(object->size, (size_t)(HEX_MAX_LINES * HEX_ROW_SIZE));
300
301 seq_printf(seq, " hex dump (first %d bytes):\n", len);
302 for (i = 0; i < len; i += HEX_ROW_SIZE) {
303 int linelen = min(remaining, HEX_ROW_SIZE);
304
305 remaining -= HEX_ROW_SIZE;
306 hex_dump_to_buffer(ptr + i, linelen, HEX_ROW_SIZE,
307 HEX_GROUP_SIZE, linebuf, sizeof(linebuf),
308 HEX_ASCII);
309 seq_printf(seq, " %s\n", linebuf);
310 }
311}
312
313/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100314 * Object colors, encoded with count and min_count:
315 * - white - orphan object, not enough references to it (count < min_count)
316 * - gray - not orphan, not marked as false positive (min_count == 0) or
317 * sufficient references to it (count >= min_count)
318 * - black - ignore, it doesn't contain references (e.g. text section)
319 * (min_count == -1). No function defined for this color.
320 * Newly created objects don't have any color assigned (object->count == -1)
321 * before the next memory scan when they become white.
322 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100323static bool color_white(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100324{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700325 return object->count != KMEMLEAK_BLACK &&
326 object->count < object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100327}
328
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100329static bool color_gray(const struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100330{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700331 return object->min_count != KMEMLEAK_BLACK &&
332 object->count >= object->min_count;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100333}
334
335/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100336 * Objects are considered unreferenced only if their color is white, they have
337 * not be deleted and have a minimum age to avoid false positives caused by
338 * pointers temporarily stored in CPU registers.
339 */
Luis R. Rodriguez4a558dd2009-09-08 16:34:50 +0100340static bool unreferenced_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100341{
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000342 return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
Catalin Marinasacf49682009-06-26 17:38:29 +0100343 time_before_eq(object->jiffies + jiffies_min_age,
344 jiffies_last_scan);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100345}
346
347/*
Catalin Marinasbab4a342009-06-26 17:38:26 +0100348 * Printing of the unreferenced objects information to the seq file. The
349 * print_unreferenced function must be called with the object->lock held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100350 */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100351static void print_unreferenced(struct seq_file *seq,
352 struct kmemleak_object *object)
353{
354 int i;
Catalin Marinasfefdd332009-10-28 13:33:12 +0000355 unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100356
Catalin Marinasbab4a342009-06-26 17:38:26 +0100357 seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
358 object->pointer, object->size);
Catalin Marinasfefdd332009-10-28 13:33:12 +0000359 seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
360 object->comm, object->pid, object->jiffies,
361 msecs_age / 1000, msecs_age % 1000);
Sergey Senozhatsky0494e082009-08-27 14:29:18 +0100362 hex_dump_object(seq, object);
Catalin Marinasbab4a342009-06-26 17:38:26 +0100363 seq_printf(seq, " backtrace:\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100364
365 for (i = 0; i < object->trace_len; i++) {
366 void *ptr = (void *)object->trace[i];
Catalin Marinasbab4a342009-06-26 17:38:26 +0100367 seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100368 }
369}
370
371/*
372 * Print the kmemleak_object information. This function is used mainly for
373 * debugging special cases when kmemleak operations. It must be called with
374 * the object->lock held.
375 */
376static void dump_object_info(struct kmemleak_object *object)
377{
378 struct stack_trace trace;
379
380 trace.nr_entries = object->trace_len;
381 trace.entries = object->trace;
382
Joe Perchesae281062009-06-23 14:40:26 +0100383 pr_notice("Object 0x%08lx (size %zu):\n",
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700384 object->pointer, object->size);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100385 pr_notice(" comm \"%s\", pid %d, jiffies %lu\n",
386 object->comm, object->pid, object->jiffies);
387 pr_notice(" min_count = %d\n", object->min_count);
388 pr_notice(" count = %d\n", object->count);
Catalin Marinas189d84e2009-08-27 14:29:15 +0100389 pr_notice(" flags = 0x%lx\n", object->flags);
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000390 pr_notice(" checksum = %d\n", object->checksum);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100391 pr_notice(" backtrace:\n");
392 print_stack_trace(&trace, 4);
393}
394
395/*
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700396 * Look-up a memory block metadata (kmemleak_object) in the object search
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100397 * tree based on a pointer value. If alias is 0, only values pointing to the
398 * beginning of the memory block are allowed. The kmemleak_lock must be held
399 * when calling this function.
400 */
401static struct kmemleak_object *lookup_object(unsigned long ptr, int alias)
402{
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700403 struct rb_node *rb = object_tree_root.rb_node;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100404
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700405 while (rb) {
406 struct kmemleak_object *object =
407 rb_entry(rb, struct kmemleak_object, rb_node);
408 if (ptr < object->pointer)
409 rb = object->rb_node.rb_left;
410 else if (object->pointer + object->size <= ptr)
411 rb = object->rb_node.rb_right;
412 else if (object->pointer == ptr || alias)
413 return object;
414 else {
Catalin Marinas5f790202011-09-28 12:17:03 +0100415 kmemleak_warn("Found object by alias at 0x%08lx\n",
416 ptr);
Catalin Marinasa7686a42010-07-19 11:54:16 +0100417 dump_object_info(object);
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700418 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100419 }
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700420 }
421 return NULL;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100422}
423
424/*
425 * Increment the object use_count. Return 1 if successful or 0 otherwise. Note
426 * that once an object's use_count reached 0, the RCU freeing was already
427 * registered and the object should no longer be used. This function must be
428 * called under the protection of rcu_read_lock().
429 */
430static int get_object(struct kmemleak_object *object)
431{
432 return atomic_inc_not_zero(&object->use_count);
433}
434
435/*
436 * RCU callback to free a kmemleak_object.
437 */
438static void free_object_rcu(struct rcu_head *rcu)
439{
Sasha Levinb67bfe02013-02-27 17:06:00 -0800440 struct hlist_node *tmp;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100441 struct kmemleak_scan_area *area;
442 struct kmemleak_object *object =
443 container_of(rcu, struct kmemleak_object, rcu);
444
445 /*
446 * Once use_count is 0 (guaranteed by put_object), there is no other
447 * code accessing this object, hence no need for locking.
448 */
Sasha Levinb67bfe02013-02-27 17:06:00 -0800449 hlist_for_each_entry_safe(area, tmp, &object->area_list, node) {
450 hlist_del(&area->node);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100451 kmem_cache_free(scan_area_cache, area);
452 }
453 kmem_cache_free(object_cache, object);
454}
455
456/*
457 * Decrement the object use_count. Once the count is 0, free the object using
458 * an RCU callback. Since put_object() may be called via the kmemleak_free() ->
459 * delete_object() path, the delayed RCU freeing ensures that there is no
460 * recursive call to the kernel allocator. Lock-less RCU object_list traversal
461 * is also possible.
462 */
463static void put_object(struct kmemleak_object *object)
464{
465 if (!atomic_dec_and_test(&object->use_count))
466 return;
467
468 /* should only get here after delete_object was called */
469 WARN_ON(object->flags & OBJECT_ALLOCATED);
470
471 call_rcu(&object->rcu, free_object_rcu);
472}
473
474/*
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700475 * Look up an object in the object search tree and increase its use_count.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100476 */
477static struct kmemleak_object *find_and_get_object(unsigned long ptr, int alias)
478{
479 unsigned long flags;
480 struct kmemleak_object *object = NULL;
481
482 rcu_read_lock();
483 read_lock_irqsave(&kmemleak_lock, flags);
484 if (ptr >= min_addr && ptr < max_addr)
485 object = lookup_object(ptr, alias);
486 read_unlock_irqrestore(&kmemleak_lock, flags);
487
488 /* check whether the object is still available */
489 if (object && !get_object(object))
490 object = NULL;
491 rcu_read_unlock();
492
493 return object;
494}
495
496/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100497 * Save stack trace to the given array of MAX_TRACE size.
498 */
499static int __save_stack_trace(unsigned long *trace)
500{
501 struct stack_trace stack_trace;
502
503 stack_trace.max_entries = MAX_TRACE;
504 stack_trace.nr_entries = 0;
505 stack_trace.entries = trace;
506 stack_trace.skip = 2;
507 save_stack_trace(&stack_trace);
508
509 return stack_trace.nr_entries;
510}
511
512/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100513 * Create the metadata (struct kmemleak_object) corresponding to an allocated
514 * memory block and add it to the object_list and object_tree_root.
515 */
Catalin Marinasfd678962009-08-27 14:29:17 +0100516static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
517 int min_count, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100518{
519 unsigned long flags;
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700520 struct kmemleak_object *object, *parent;
521 struct rb_node **link, *rb_parent;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100522
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000523 object = kmem_cache_alloc(object_cache, gfp_kmemleak_mask(gfp));
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100524 if (!object) {
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000525 pr_warning("Cannot allocate a kmemleak_object structure\n");
526 kmemleak_disable();
Catalin Marinasfd678962009-08-27 14:29:17 +0100527 return NULL;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100528 }
529
530 INIT_LIST_HEAD(&object->object_list);
531 INIT_LIST_HEAD(&object->gray_list);
532 INIT_HLIST_HEAD(&object->area_list);
533 spin_lock_init(&object->lock);
534 atomic_set(&object->use_count, 1);
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000535 object->flags = OBJECT_ALLOCATED;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100536 object->pointer = ptr;
537 object->size = size;
538 object->min_count = min_count;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000539 object->count = 0; /* white color initially */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100540 object->jiffies = jiffies;
Catalin Marinas04609ccc2009-10-28 13:33:12 +0000541 object->checksum = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100542
543 /* task information */
544 if (in_irq()) {
545 object->pid = 0;
546 strncpy(object->comm, "hardirq", sizeof(object->comm));
547 } else if (in_softirq()) {
548 object->pid = 0;
549 strncpy(object->comm, "softirq", sizeof(object->comm));
550 } else {
551 object->pid = current->pid;
552 /*
553 * There is a small chance of a race with set_task_comm(),
554 * however using get_task_comm() here may cause locking
555 * dependency issues with current->alloc_lock. In the worst
556 * case, the command line is not correct.
557 */
558 strncpy(object->comm, current->comm, sizeof(object->comm));
559 }
560
561 /* kernel backtrace */
Catalin Marinasfd678962009-08-27 14:29:17 +0100562 object->trace_len = __save_stack_trace(object->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100563
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100564 write_lock_irqsave(&kmemleak_lock, flags);
Luis R. Rodriguez0580a182009-09-08 17:32:34 +0100565
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100566 min_addr = min(min_addr, ptr);
567 max_addr = max(max_addr, ptr + size);
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700568 link = &object_tree_root.rb_node;
569 rb_parent = NULL;
570 while (*link) {
571 rb_parent = *link;
572 parent = rb_entry(rb_parent, struct kmemleak_object, rb_node);
573 if (ptr + size <= parent->pointer)
574 link = &parent->rb_node.rb_left;
575 else if (parent->pointer + parent->size <= ptr)
576 link = &parent->rb_node.rb_right;
577 else {
578 kmemleak_stop("Cannot insert 0x%lx into the object "
579 "search tree (overlaps existing)\n",
580 ptr);
581 kmem_cache_free(object_cache, object);
582 object = parent;
583 spin_lock(&object->lock);
584 dump_object_info(object);
585 spin_unlock(&object->lock);
586 goto out;
587 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100588 }
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700589 rb_link_node(&object->rb_node, rb_parent, link);
590 rb_insert_color(&object->rb_node, &object_tree_root);
591
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100592 list_add_tail_rcu(&object->object_list, &object_list);
593out:
594 write_unlock_irqrestore(&kmemleak_lock, flags);
Catalin Marinasfd678962009-08-27 14:29:17 +0100595 return object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100596}
597
598/*
599 * Remove the metadata (struct kmemleak_object) for a memory block from the
600 * object_list and object_tree_root and decrement its use_count.
601 */
Catalin Marinas53238a62009-07-07 10:33:00 +0100602static void __delete_object(struct kmemleak_object *object)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100603{
604 unsigned long flags;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100605
606 write_lock_irqsave(&kmemleak_lock, flags);
Michel Lespinasse85d3a312012-10-08 16:31:27 -0700607 rb_erase(&object->rb_node, &object_tree_root);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100608 list_del_rcu(&object->object_list);
609 write_unlock_irqrestore(&kmemleak_lock, flags);
610
611 WARN_ON(!(object->flags & OBJECT_ALLOCATED));
Catalin Marinas53238a62009-07-07 10:33:00 +0100612 WARN_ON(atomic_read(&object->use_count) < 2);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100613
614 /*
615 * Locking here also ensures that the corresponding memory block
616 * cannot be freed when it is being scanned.
617 */
618 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100619 object->flags &= ~OBJECT_ALLOCATED;
620 spin_unlock_irqrestore(&object->lock, flags);
621 put_object(object);
622}
623
624/*
Catalin Marinas53238a62009-07-07 10:33:00 +0100625 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
626 * delete it.
627 */
628static void delete_object_full(unsigned long ptr)
629{
630 struct kmemleak_object *object;
631
632 object = find_and_get_object(ptr, 0);
633 if (!object) {
634#ifdef DEBUG
635 kmemleak_warn("Freeing unknown object at 0x%08lx\n",
636 ptr);
637#endif
638 return;
639 }
640 __delete_object(object);
641 put_object(object);
642}
643
644/*
645 * Look up the metadata (struct kmemleak_object) corresponding to ptr and
646 * delete it. If the memory block is partially freed, the function may create
647 * additional metadata for the remaining parts of the block.
648 */
649static void delete_object_part(unsigned long ptr, size_t size)
650{
651 struct kmemleak_object *object;
652 unsigned long start, end;
653
654 object = find_and_get_object(ptr, 1);
655 if (!object) {
656#ifdef DEBUG
657 kmemleak_warn("Partially freeing unknown object at 0x%08lx "
658 "(size %zu)\n", ptr, size);
659#endif
660 return;
661 }
662 __delete_object(object);
663
664 /*
665 * Create one or two objects that may result from the memory block
666 * split. Note that partial freeing is only done by free_bootmem() and
667 * this happens before kmemleak_init() is called. The path below is
668 * only executed during early log recording in kmemleak_init(), so
669 * GFP_KERNEL is enough.
670 */
671 start = object->pointer;
672 end = object->pointer + object->size;
673 if (ptr > start)
674 create_object(start, ptr - start, object->min_count,
675 GFP_KERNEL);
676 if (ptr + size < end)
677 create_object(ptr + size, end - ptr - size, object->min_count,
678 GFP_KERNEL);
679
680 put_object(object);
681}
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700682
683static void __paint_it(struct kmemleak_object *object, int color)
684{
685 object->min_count = color;
686 if (color == KMEMLEAK_BLACK)
687 object->flags |= OBJECT_NO_SCAN;
688}
689
690static void paint_it(struct kmemleak_object *object, int color)
691{
692 unsigned long flags;
693
694 spin_lock_irqsave(&object->lock, flags);
695 __paint_it(object, color);
696 spin_unlock_irqrestore(&object->lock, flags);
697}
698
699static void paint_ptr(unsigned long ptr, int color)
700{
701 struct kmemleak_object *object;
702
703 object = find_and_get_object(ptr, 0);
704 if (!object) {
705 kmemleak_warn("Trying to color unknown object "
706 "at 0x%08lx as %s\n", ptr,
707 (color == KMEMLEAK_GREY) ? "Grey" :
708 (color == KMEMLEAK_BLACK) ? "Black" : "Unknown");
709 return;
710 }
711 paint_it(object, color);
712 put_object(object);
713}
714
Catalin Marinas53238a62009-07-07 10:33:00 +0100715/*
Holger Hans Peter Freyther145b64b2010-07-22 19:54:13 +0800716 * Mark an object permanently as gray-colored so that it can no longer be
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100717 * reported as a leak. This is used in general to mark a false positive.
718 */
719static void make_gray_object(unsigned long ptr)
720{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700721 paint_ptr(ptr, KMEMLEAK_GREY);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100722}
723
724/*
725 * Mark the object as black-colored so that it is ignored from scans and
726 * reporting.
727 */
728static void make_black_object(unsigned long ptr)
729{
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -0700730 paint_ptr(ptr, KMEMLEAK_BLACK);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100731}
732
733/*
734 * Add a scanning area to the object. If at least one such area is added,
735 * kmemleak will only scan these ranges rather than the whole memory block.
736 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000737static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100738{
739 unsigned long flags;
740 struct kmemleak_object *object;
741 struct kmemleak_scan_area *area;
742
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000743 object = find_and_get_object(ptr, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100744 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100745 kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
746 ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100747 return;
748 }
749
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000750 area = kmem_cache_alloc(scan_area_cache, gfp_kmemleak_mask(gfp));
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100751 if (!area) {
Catalin Marinas6ae4bd12011-01-27 10:30:26 +0000752 pr_warning("Cannot allocate a scan area\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100753 goto out;
754 }
755
756 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas7f88f882013-11-12 15:07:45 -0800757 if (size == SIZE_MAX) {
758 size = object->pointer + object->size - ptr;
759 } else if (ptr + size > object->pointer + object->size) {
Joe Perchesae281062009-06-23 14:40:26 +0100760 kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100761 dump_object_info(object);
762 kmem_cache_free(scan_area_cache, area);
763 goto out_unlock;
764 }
765
766 INIT_HLIST_NODE(&area->node);
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000767 area->start = ptr;
768 area->size = size;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100769
770 hlist_add_head(&area->node, &object->area_list);
771out_unlock:
772 spin_unlock_irqrestore(&object->lock, flags);
773out:
774 put_object(object);
775}
776
777/*
778 * Set the OBJECT_NO_SCAN flag for the object corresponding to the give
779 * pointer. Such object will not be scanned by kmemleak but references to it
780 * are searched.
781 */
782static void object_no_scan(unsigned long ptr)
783{
784 unsigned long flags;
785 struct kmemleak_object *object;
786
787 object = find_and_get_object(ptr, 0);
788 if (!object) {
Joe Perchesae281062009-06-23 14:40:26 +0100789 kmemleak_warn("Not scanning unknown object at 0x%08lx\n", ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100790 return;
791 }
792
793 spin_lock_irqsave(&object->lock, flags);
794 object->flags |= OBJECT_NO_SCAN;
795 spin_unlock_irqrestore(&object->lock, flags);
796 put_object(object);
797}
798
799/*
800 * Log an early kmemleak_* call to the early_log buffer. These calls will be
801 * processed later once kmemleak is fully initialized.
802 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100803static void __init log_early(int op_type, const void *ptr, size_t size,
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000804 int min_count)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100805{
806 unsigned long flags;
807 struct early_log *log;
808
Catalin Marinasb6693002011-09-28 17:22:56 +0100809 if (atomic_read(&kmemleak_error)) {
810 /* kmemleak stopped recording, just count the requests */
811 crt_early_log++;
812 return;
813 }
814
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100815 if (crt_early_log >= ARRAY_SIZE(early_log)) {
Catalin Marinasa9d90582009-06-25 10:16:11 +0100816 kmemleak_disable();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100817 return;
818 }
819
820 /*
821 * There is no need for locking since the kernel is still in UP mode
822 * at this stage. Disabling the IRQs is enough.
823 */
824 local_irq_save(flags);
825 log = &early_log[crt_early_log];
826 log->op_type = op_type;
827 log->ptr = ptr;
828 log->size = size;
829 log->min_count = min_count;
Catalin Marinas5f790202011-09-28 12:17:03 +0100830 log->trace_len = __save_stack_trace(log->trace);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100831 crt_early_log++;
832 local_irq_restore(flags);
833}
834
835/*
Catalin Marinasfd678962009-08-27 14:29:17 +0100836 * Log an early allocated block and populate the stack trace.
837 */
838static void early_alloc(struct early_log *log)
839{
840 struct kmemleak_object *object;
841 unsigned long flags;
842 int i;
843
844 if (!atomic_read(&kmemleak_enabled) || !log->ptr || IS_ERR(log->ptr))
845 return;
846
847 /*
848 * RCU locking needed to ensure object is not freed via put_object().
849 */
850 rcu_read_lock();
851 object = create_object((unsigned long)log->ptr, log->size,
Tetsuo Handac1bcd6b2009-10-09 10:39:24 +0100852 log->min_count, GFP_ATOMIC);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100853 if (!object)
854 goto out;
Catalin Marinasfd678962009-08-27 14:29:17 +0100855 spin_lock_irqsave(&object->lock, flags);
856 for (i = 0; i < log->trace_len; i++)
857 object->trace[i] = log->trace[i];
858 object->trace_len = log->trace_len;
859 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0d5d1aa2009-10-09 10:30:34 +0100860out:
Catalin Marinasfd678962009-08-27 14:29:17 +0100861 rcu_read_unlock();
862}
863
Catalin Marinasf528f0b2011-09-26 17:12:53 +0100864/*
865 * Log an early allocated block and populate the stack trace.
866 */
867static void early_alloc_percpu(struct early_log *log)
868{
869 unsigned int cpu;
870 const void __percpu *ptr = log->ptr;
871
872 for_each_possible_cpu(cpu) {
873 log->ptr = per_cpu_ptr(ptr, cpu);
874 early_alloc(log);
875 }
876}
877
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100878/**
879 * kmemleak_alloc - register a newly allocated object
880 * @ptr: pointer to beginning of the object
881 * @size: size of the object
882 * @min_count: minimum number of references to this object. If during memory
883 * scanning a number of references less than @min_count is found,
884 * the object is reported as a memory leak. If @min_count is 0,
885 * the object is never reported as a leak. If @min_count is -1,
886 * the object is ignored (not scanned and not reported as a leak)
887 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
888 *
889 * This function is called from the kernel allocators when a new object
890 * (memory block) is allocated (kmem_cache_alloc, kmalloc, vmalloc etc.).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100891 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100892void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
893 gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100894{
895 pr_debug("%s(0x%p, %zu, %d)\n", __func__, ptr, size, min_count);
896
897 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
898 create_object((unsigned long)ptr, size, min_count, gfp);
899 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000900 log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100901}
902EXPORT_SYMBOL_GPL(kmemleak_alloc);
903
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100904/**
Catalin Marinasf528f0b2011-09-26 17:12:53 +0100905 * kmemleak_alloc_percpu - register a newly allocated __percpu object
906 * @ptr: __percpu pointer to beginning of the object
907 * @size: size of the object
908 *
909 * This function is called from the kernel percpu allocator when a new object
910 * (memory block) is allocated (alloc_percpu). It assumes GFP_KERNEL
911 * allocation.
912 */
913void __ref kmemleak_alloc_percpu(const void __percpu *ptr, size_t size)
914{
915 unsigned int cpu;
916
917 pr_debug("%s(0x%p, %zu)\n", __func__, ptr, size);
918
919 /*
920 * Percpu allocations are only scanned and not reported as leaks
921 * (min_count is set to 0).
922 */
923 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
924 for_each_possible_cpu(cpu)
925 create_object((unsigned long)per_cpu_ptr(ptr, cpu),
926 size, 0, GFP_KERNEL);
927 else if (atomic_read(&kmemleak_early_log))
928 log_early(KMEMLEAK_ALLOC_PERCPU, ptr, size, 0);
929}
930EXPORT_SYMBOL_GPL(kmemleak_alloc_percpu);
931
932/**
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100933 * kmemleak_free - unregister a previously registered object
934 * @ptr: pointer to beginning of the object
935 *
936 * This function is called from the kernel allocators when an object (memory
937 * block) is freed (kmem_cache_free, kfree, vfree etc.).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100938 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100939void __ref kmemleak_free(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100940{
941 pr_debug("%s(0x%p)\n", __func__, ptr);
942
943 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
Catalin Marinas53238a62009-07-07 10:33:00 +0100944 delete_object_full((unsigned long)ptr);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100945 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000946 log_early(KMEMLEAK_FREE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100947}
948EXPORT_SYMBOL_GPL(kmemleak_free);
949
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100950/**
951 * kmemleak_free_part - partially unregister a previously registered object
952 * @ptr: pointer to the beginning or inside the object. This also
953 * represents the start of the range to be freed
954 * @size: size to be unregistered
955 *
956 * This function is called when only a part of a memory block is freed
957 * (usually from the bootmem allocator).
Catalin Marinas53238a62009-07-07 10:33:00 +0100958 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100959void __ref kmemleak_free_part(const void *ptr, size_t size)
Catalin Marinas53238a62009-07-07 10:33:00 +0100960{
961 pr_debug("%s(0x%p)\n", __func__, ptr);
962
963 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
964 delete_object_part((unsigned long)ptr, size);
965 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +0000966 log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
Catalin Marinas53238a62009-07-07 10:33:00 +0100967}
968EXPORT_SYMBOL_GPL(kmemleak_free_part);
969
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100970/**
Catalin Marinasf528f0b2011-09-26 17:12:53 +0100971 * kmemleak_free_percpu - unregister a previously registered __percpu object
972 * @ptr: __percpu pointer to beginning of the object
973 *
974 * This function is called from the kernel percpu allocator when an object
975 * (memory block) is freed (free_percpu).
976 */
977void __ref kmemleak_free_percpu(const void __percpu *ptr)
978{
979 unsigned int cpu;
980
981 pr_debug("%s(0x%p)\n", __func__, ptr);
982
983 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
984 for_each_possible_cpu(cpu)
985 delete_object_full((unsigned long)per_cpu_ptr(ptr,
986 cpu));
987 else if (atomic_read(&kmemleak_early_log))
988 log_early(KMEMLEAK_FREE_PERCPU, ptr, 0, 0);
989}
990EXPORT_SYMBOL_GPL(kmemleak_free_percpu);
991
992/**
Catalin Marinasa2b6bf62010-07-19 11:54:17 +0100993 * kmemleak_not_leak - mark an allocated object as false positive
994 * @ptr: pointer to beginning of the object
995 *
996 * Calling this function on an object will cause the memory block to no longer
997 * be reported as leak and always be scanned.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +0100998 */
Catalin Marinasa6186d82009-08-27 14:29:16 +0100999void __ref kmemleak_not_leak(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001000{
1001 pr_debug("%s(0x%p)\n", __func__, ptr);
1002
1003 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
1004 make_gray_object((unsigned long)ptr);
1005 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001006 log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001007}
1008EXPORT_SYMBOL(kmemleak_not_leak);
1009
Catalin Marinasa2b6bf62010-07-19 11:54:17 +01001010/**
1011 * kmemleak_ignore - ignore an allocated object
1012 * @ptr: pointer to beginning of the object
1013 *
1014 * Calling this function on an object will cause the memory block to be
1015 * ignored (not scanned and not reported as a leak). This is usually done when
1016 * it is known that the corresponding block is not a leak and does not contain
1017 * any references to other allocated memory blocks.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001018 */
Catalin Marinasa6186d82009-08-27 14:29:16 +01001019void __ref kmemleak_ignore(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001020{
1021 pr_debug("%s(0x%p)\n", __func__, ptr);
1022
1023 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
1024 make_black_object((unsigned long)ptr);
1025 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001026 log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001027}
1028EXPORT_SYMBOL(kmemleak_ignore);
1029
Catalin Marinasa2b6bf62010-07-19 11:54:17 +01001030/**
1031 * kmemleak_scan_area - limit the range to be scanned in an allocated object
1032 * @ptr: pointer to beginning or inside the object. This also
1033 * represents the start of the scan area
1034 * @size: size of the scan area
1035 * @gfp: kmalloc() flags used for kmemleak internal memory allocations
1036 *
1037 * This function is used when it is known that only certain parts of an object
1038 * contain references to other objects. Kmemleak will only scan these areas
1039 * reducing the number false negatives.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001040 */
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001041void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001042{
1043 pr_debug("%s(0x%p)\n", __func__, ptr);
1044
Tiejun Chenb469d432012-01-11 05:51:10 +00001045 if (atomic_read(&kmemleak_enabled) && ptr && size && !IS_ERR(ptr))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001046 add_scan_area((unsigned long)ptr, size, gfp);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001047 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001048 log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001049}
1050EXPORT_SYMBOL(kmemleak_scan_area);
1051
Catalin Marinasa2b6bf62010-07-19 11:54:17 +01001052/**
1053 * kmemleak_no_scan - do not scan an allocated object
1054 * @ptr: pointer to beginning of the object
1055 *
1056 * This function notifies kmemleak not to scan the given memory block. Useful
1057 * in situations where it is known that the given object does not contain any
1058 * references to other objects. Kmemleak will not scan such objects reducing
1059 * the number of false negatives.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001060 */
Catalin Marinasa6186d82009-08-27 14:29:16 +01001061void __ref kmemleak_no_scan(const void *ptr)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001062{
1063 pr_debug("%s(0x%p)\n", __func__, ptr);
1064
1065 if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
1066 object_no_scan((unsigned long)ptr);
1067 else if (atomic_read(&kmemleak_early_log))
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001068 log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001069}
1070EXPORT_SYMBOL(kmemleak_no_scan);
1071
1072/*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001073 * Update an object's checksum and return true if it was modified.
1074 */
1075static bool update_checksum(struct kmemleak_object *object)
1076{
1077 u32 old_csum = object->checksum;
1078
1079 if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
1080 return false;
1081
1082 object->checksum = crc32(0, (void *)object->pointer, object->size);
1083 return object->checksum != old_csum;
1084}
1085
1086/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001087 * Memory scanning is a long process and it needs to be interruptable. This
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001088 * function checks whether such interrupt condition occurred.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001089 */
1090static int scan_should_stop(void)
1091{
1092 if (!atomic_read(&kmemleak_enabled))
1093 return 1;
1094
1095 /*
1096 * This function may be called from either process or kthread context,
1097 * hence the need to check for both stop conditions.
1098 */
1099 if (current->mm)
1100 return signal_pending(current);
1101 else
1102 return kthread_should_stop();
1103
1104 return 0;
1105}
1106
1107/*
1108 * Scan a memory block (exclusive range) for valid pointers and add those
1109 * found to the gray list.
1110 */
1111static void scan_block(void *_start, void *_end,
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001112 struct kmemleak_object *scanned, int allow_resched)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001113{
1114 unsigned long *ptr;
1115 unsigned long *start = PTR_ALIGN(_start, BYTES_PER_POINTER);
1116 unsigned long *end = _end - (BYTES_PER_POINTER - 1);
1117
1118 for (ptr = start; ptr < end; ptr++) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001119 struct kmemleak_object *object;
Pekka Enberg8e019362009-08-27 14:50:00 +01001120 unsigned long flags;
1121 unsigned long pointer;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001122
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001123 if (allow_resched)
1124 cond_resched();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001125 if (scan_should_stop())
1126 break;
1127
Pekka Enberg8e019362009-08-27 14:50:00 +01001128 /* don't scan uninitialized memory */
1129 if (!kmemcheck_is_obj_initialized((unsigned long)ptr,
1130 BYTES_PER_POINTER))
1131 continue;
1132
1133 pointer = *ptr;
1134
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001135 object = find_and_get_object(pointer, 1);
1136 if (!object)
1137 continue;
1138 if (object == scanned) {
1139 /* self referenced, ignore */
1140 put_object(object);
1141 continue;
1142 }
1143
1144 /*
1145 * Avoid the lockdep recursive warning on object->lock being
1146 * previously acquired in scan_object(). These locks are
1147 * enclosed by scan_mutex.
1148 */
1149 spin_lock_irqsave_nested(&object->lock, flags,
1150 SINGLE_DEPTH_NESTING);
1151 if (!color_white(object)) {
1152 /* non-orphan, ignored or new */
1153 spin_unlock_irqrestore(&object->lock, flags);
1154 put_object(object);
1155 continue;
1156 }
1157
1158 /*
1159 * Increase the object's reference count (number of pointers
1160 * to the memory block). If this count reaches the required
1161 * minimum, the object's color will become gray and it will be
1162 * added to the gray_list.
1163 */
1164 object->count++;
Catalin Marinas0587da42009-10-28 13:33:11 +00001165 if (color_gray(object)) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001166 list_add_tail(&object->gray_list, &gray_list);
Catalin Marinas0587da42009-10-28 13:33:11 +00001167 spin_unlock_irqrestore(&object->lock, flags);
1168 continue;
1169 }
1170
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001171 spin_unlock_irqrestore(&object->lock, flags);
Catalin Marinas0587da42009-10-28 13:33:11 +00001172 put_object(object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001173 }
1174}
1175
1176/*
1177 * Scan a memory block corresponding to a kmemleak_object. A condition is
1178 * that object->use_count >= 1.
1179 */
1180static void scan_object(struct kmemleak_object *object)
1181{
1182 struct kmemleak_scan_area *area;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001183 unsigned long flags;
1184
1185 /*
Uwe Kleine-König21ae2952009-10-07 15:21:09 +02001186 * Once the object->lock is acquired, the corresponding memory block
1187 * cannot be freed (the same lock is acquired in delete_object).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001188 */
1189 spin_lock_irqsave(&object->lock, flags);
1190 if (object->flags & OBJECT_NO_SCAN)
1191 goto out;
1192 if (!(object->flags & OBJECT_ALLOCATED))
1193 /* already freed object */
1194 goto out;
Catalin Marinasaf986032009-08-27 14:29:12 +01001195 if (hlist_empty(&object->area_list)) {
1196 void *start = (void *)object->pointer;
1197 void *end = (void *)(object->pointer + object->size);
1198
1199 while (start < end && (object->flags & OBJECT_ALLOCATED) &&
1200 !(object->flags & OBJECT_NO_SCAN)) {
1201 scan_block(start, min(start + MAX_SCAN_SIZE, end),
1202 object, 0);
1203 start += MAX_SCAN_SIZE;
1204
1205 spin_unlock_irqrestore(&object->lock, flags);
1206 cond_resched();
1207 spin_lock_irqsave(&object->lock, flags);
1208 }
1209 } else
Sasha Levinb67bfe02013-02-27 17:06:00 -08001210 hlist_for_each_entry(area, &object->area_list, node)
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001211 scan_block((void *)area->start,
1212 (void *)(area->start + area->size),
1213 object, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001214out:
1215 spin_unlock_irqrestore(&object->lock, flags);
1216}
1217
1218/*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001219 * Scan the objects already referenced (gray objects). More objects will be
1220 * referenced and, if there are no memory leaks, all the objects are scanned.
1221 */
1222static void scan_gray_list(void)
1223{
1224 struct kmemleak_object *object, *tmp;
1225
1226 /*
1227 * The list traversal is safe for both tail additions and removals
1228 * from inside the loop. The kmemleak objects cannot be freed from
1229 * outside the loop because their use_count was incremented.
1230 */
1231 object = list_entry(gray_list.next, typeof(*object), gray_list);
1232 while (&object->gray_list != &gray_list) {
1233 cond_resched();
1234
1235 /* may add new objects to the list */
1236 if (!scan_should_stop())
1237 scan_object(object);
1238
1239 tmp = list_entry(object->gray_list.next, typeof(*object),
1240 gray_list);
1241
1242 /* remove the object from the list and release it */
1243 list_del(&object->gray_list);
1244 put_object(object);
1245
1246 object = tmp;
1247 }
1248 WARN_ON(!list_empty(&gray_list));
1249}
1250
1251/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001252 * Scan data sections and all the referenced memory blocks allocated via the
1253 * kernel's standard allocators. This function must be called with the
1254 * scan_mutex held.
1255 */
1256static void kmemleak_scan(void)
1257{
1258 unsigned long flags;
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001259 struct kmemleak_object *object;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001260 int i;
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001261 int new_leaks = 0;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001262
Catalin Marinasacf49682009-06-26 17:38:29 +01001263 jiffies_last_scan = jiffies;
1264
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001265 /* prepare the kmemleak_object's */
1266 rcu_read_lock();
1267 list_for_each_entry_rcu(object, &object_list, object_list) {
1268 spin_lock_irqsave(&object->lock, flags);
1269#ifdef DEBUG
1270 /*
1271 * With a few exceptions there should be a maximum of
1272 * 1 reference to any object at this point.
1273 */
1274 if (atomic_read(&object->use_count) > 1) {
Joe Perchesae281062009-06-23 14:40:26 +01001275 pr_debug("object->use_count = %d\n",
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001276 atomic_read(&object->use_count));
1277 dump_object_info(object);
1278 }
1279#endif
1280 /* reset the reference count (whiten the object) */
1281 object->count = 0;
1282 if (color_gray(object) && get_object(object))
1283 list_add_tail(&object->gray_list, &gray_list);
1284
1285 spin_unlock_irqrestore(&object->lock, flags);
1286 }
1287 rcu_read_unlock();
1288
1289 /* data/bss scanning */
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001290 scan_block(_sdata, _edata, NULL, 1);
1291 scan_block(__bss_start, __bss_stop, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001292
1293#ifdef CONFIG_SMP
1294 /* per-cpu sections scanning */
1295 for_each_possible_cpu(i)
1296 scan_block(__per_cpu_start + per_cpu_offset(i),
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001297 __per_cpu_end + per_cpu_offset(i), NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001298#endif
1299
1300 /*
Laura Abbott029aeff2011-11-15 23:49:09 +00001301 * Struct page scanning for each node.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001302 */
Laura Abbott029aeff2011-11-15 23:49:09 +00001303 lock_memory_hotplug();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001304 for_each_online_node(i) {
Cody P Schafer108bcc92013-02-22 16:35:23 -08001305 unsigned long start_pfn = node_start_pfn(i);
1306 unsigned long end_pfn = node_end_pfn(i);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001307 unsigned long pfn;
1308
1309 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
1310 struct page *page;
1311
1312 if (!pfn_valid(pfn))
1313 continue;
1314 page = pfn_to_page(pfn);
1315 /* only scan if page is in use */
1316 if (page_count(page) == 0)
1317 continue;
Catalin Marinas4b8a9672009-07-07 10:32:56 +01001318 scan_block(page, page + 1, NULL, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001319 }
1320 }
Laura Abbott029aeff2011-11-15 23:49:09 +00001321 unlock_memory_hotplug();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001322
1323 /*
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001324 * Scanning the task stacks (may introduce false negatives).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001325 */
1326 if (kmemleak_stack_scan) {
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001327 struct task_struct *p, *g;
1328
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001329 read_lock(&tasklist_lock);
Catalin Marinas43ed5d62009-09-01 11:12:44 +01001330 do_each_thread(g, p) {
1331 scan_block(task_stack_page(p), task_stack_page(p) +
1332 THREAD_SIZE, NULL, 0);
1333 } while_each_thread(g, p);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001334 read_unlock(&tasklist_lock);
1335 }
1336
1337 /*
1338 * Scan the objects already referenced from the sections scanned
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001339 * above.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001340 */
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001341 scan_gray_list();
Catalin Marinas25873622009-07-07 10:32:58 +01001342
1343 /*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001344 * Check for new or unreferenced objects modified since the previous
1345 * scan and color them gray until the next scan.
Catalin Marinas25873622009-07-07 10:32:58 +01001346 */
1347 rcu_read_lock();
1348 list_for_each_entry_rcu(object, &object_list, object_list) {
1349 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001350 if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
1351 && update_checksum(object) && get_object(object)) {
1352 /* color it gray temporarily */
1353 object->count = object->min_count;
Catalin Marinas25873622009-07-07 10:32:58 +01001354 list_add_tail(&object->gray_list, &gray_list);
1355 }
1356 spin_unlock_irqrestore(&object->lock, flags);
1357 }
1358 rcu_read_unlock();
1359
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001360 /*
1361 * Re-scan the gray list for modified unreferenced objects.
1362 */
1363 scan_gray_list();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001364
1365 /*
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001366 * If scanning was stopped do not report any new unreferenced objects.
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001367 */
Catalin Marinas04609ccc2009-10-28 13:33:12 +00001368 if (scan_should_stop())
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001369 return;
1370
1371 /*
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001372 * Scanning result reporting.
1373 */
1374 rcu_read_lock();
1375 list_for_each_entry_rcu(object, &object_list, object_list) {
1376 spin_lock_irqsave(&object->lock, flags);
1377 if (unreferenced_object(object) &&
1378 !(object->flags & OBJECT_REPORTED)) {
1379 object->flags |= OBJECT_REPORTED;
1380 new_leaks++;
1381 }
1382 spin_unlock_irqrestore(&object->lock, flags);
1383 }
1384 rcu_read_unlock();
1385
Li Zefandc9b3f42014-04-03 14:46:26 -07001386 if (new_leaks) {
1387 kmemleak_found_leaks = true;
1388
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001389 pr_info("%d new suspected memory leaks (see "
1390 "/sys/kernel/debug/kmemleak)\n", new_leaks);
Li Zefandc9b3f42014-04-03 14:46:26 -07001391 }
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001392
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001393}
1394
1395/*
1396 * Thread function performing automatic memory scanning. Unreferenced objects
1397 * at the end of a memory scan are reported but only the first time.
1398 */
1399static int kmemleak_scan_thread(void *arg)
1400{
1401 static int first_run = 1;
1402
Joe Perchesae281062009-06-23 14:40:26 +01001403 pr_info("Automatic memory scanning thread started\n");
Catalin Marinasbf2a76b2009-07-07 10:32:55 +01001404 set_user_nice(current, 10);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001405
1406 /*
1407 * Wait before the first scan to allow the system to fully initialize.
1408 */
1409 if (first_run) {
1410 first_run = 0;
1411 ssleep(SECS_FIRST_SCAN);
1412 }
1413
1414 while (!kthread_should_stop()) {
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001415 signed long timeout = jiffies_scan_wait;
1416
1417 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001418 kmemleak_scan();
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001419 mutex_unlock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001420
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001421 /* wait before the next scan */
1422 while (timeout && !kthread_should_stop())
1423 timeout = schedule_timeout_interruptible(timeout);
1424 }
1425
Joe Perchesae281062009-06-23 14:40:26 +01001426 pr_info("Automatic memory scanning thread ended\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001427
1428 return 0;
1429}
1430
1431/*
1432 * Start the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001433 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001434 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001435static void start_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001436{
1437 if (scan_thread)
1438 return;
1439 scan_thread = kthread_run(kmemleak_scan_thread, NULL, "kmemleak");
1440 if (IS_ERR(scan_thread)) {
Joe Perchesae281062009-06-23 14:40:26 +01001441 pr_warning("Failed to create the scan thread\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001442 scan_thread = NULL;
1443 }
1444}
1445
1446/*
1447 * Stop the automatic memory scanning thread. This function must be called
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001448 * with the scan_mutex held.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001449 */
Luis R. Rodriguez7eb0d5e2009-09-08 17:31:45 +01001450static void stop_scan_thread(void)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001451{
1452 if (scan_thread) {
1453 kthread_stop(scan_thread);
1454 scan_thread = NULL;
1455 }
1456}
1457
1458/*
1459 * Iterate over the object_list and return the first valid object at or after
1460 * the required position with its use_count incremented. The function triggers
1461 * a memory scanning when the pos argument points to the first position.
1462 */
1463static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
1464{
1465 struct kmemleak_object *object;
1466 loff_t n = *pos;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001467 int err;
1468
1469 err = mutex_lock_interruptible(&scan_mutex);
1470 if (err < 0)
1471 return ERR_PTR(err);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001472
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001473 rcu_read_lock();
1474 list_for_each_entry_rcu(object, &object_list, object_list) {
1475 if (n-- > 0)
1476 continue;
1477 if (get_object(object))
1478 goto out;
1479 }
1480 object = NULL;
1481out:
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001482 return object;
1483}
1484
1485/*
1486 * Return the next object in the object_list. The function decrements the
1487 * use_count of the previous object and increases that of the next one.
1488 */
1489static void *kmemleak_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1490{
1491 struct kmemleak_object *prev_obj = v;
1492 struct kmemleak_object *next_obj = NULL;
Michael Wang58fac092012-08-17 12:33:34 +08001493 struct kmemleak_object *obj = prev_obj;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001494
1495 ++(*pos);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001496
Michael Wang58fac092012-08-17 12:33:34 +08001497 list_for_each_entry_continue_rcu(obj, &object_list, object_list) {
Catalin Marinas52c3ce42011-04-27 16:44:26 +01001498 if (get_object(obj)) {
1499 next_obj = obj;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001500 break;
Catalin Marinas52c3ce42011-04-27 16:44:26 +01001501 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001502 }
Catalin Marinas288c8572009-07-07 10:32:57 +01001503
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001504 put_object(prev_obj);
1505 return next_obj;
1506}
1507
1508/*
1509 * Decrement the use_count of the last object required, if any.
1510 */
1511static void kmemleak_seq_stop(struct seq_file *seq, void *v)
1512{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001513 if (!IS_ERR(v)) {
1514 /*
1515 * kmemleak_seq_start may return ERR_PTR if the scan_mutex
1516 * waiting was interrupted, so only release it if !IS_ERR.
1517 */
Catalin Marinasf5886c72009-07-29 16:26:57 +01001518 rcu_read_unlock();
Catalin Marinasb87324d2009-07-07 10:32:58 +01001519 mutex_unlock(&scan_mutex);
1520 if (v)
1521 put_object(v);
1522 }
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001523}
1524
1525/*
1526 * Print the information for an unreferenced object to the seq file.
1527 */
1528static int kmemleak_seq_show(struct seq_file *seq, void *v)
1529{
1530 struct kmemleak_object *object = v;
1531 unsigned long flags;
1532
1533 spin_lock_irqsave(&object->lock, flags);
Catalin Marinas288c8572009-07-07 10:32:57 +01001534 if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object))
Catalin Marinas17bb9e02009-06-29 17:13:56 +01001535 print_unreferenced(seq, object);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001536 spin_unlock_irqrestore(&object->lock, flags);
1537 return 0;
1538}
1539
1540static const struct seq_operations kmemleak_seq_ops = {
1541 .start = kmemleak_seq_start,
1542 .next = kmemleak_seq_next,
1543 .stop = kmemleak_seq_stop,
1544 .show = kmemleak_seq_show,
1545};
1546
1547static int kmemleak_open(struct inode *inode, struct file *file)
1548{
Catalin Marinasb87324d2009-07-07 10:32:58 +01001549 return seq_open(file, &kmemleak_seq_ops);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001550}
1551
Catalin Marinas189d84e2009-08-27 14:29:15 +01001552static int dump_str_object_info(const char *str)
1553{
1554 unsigned long flags;
1555 struct kmemleak_object *object;
1556 unsigned long addr;
1557
Abhijit Pawardc053732012-12-18 14:23:27 -08001558 if (kstrtoul(str, 0, &addr))
1559 return -EINVAL;
Catalin Marinas189d84e2009-08-27 14:29:15 +01001560 object = find_and_get_object(addr, 0);
1561 if (!object) {
1562 pr_info("Unknown object at 0x%08lx\n", addr);
1563 return -EINVAL;
1564 }
1565
1566 spin_lock_irqsave(&object->lock, flags);
1567 dump_object_info(object);
1568 spin_unlock_irqrestore(&object->lock, flags);
1569
1570 put_object(object);
1571 return 0;
1572}
1573
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001574/*
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001575 * We use grey instead of black to ensure we can do future scans on the same
1576 * objects. If we did not do future scans these black objects could
1577 * potentially contain references to newly allocated objects in the future and
1578 * we'd end up with false positives.
1579 */
1580static void kmemleak_clear(void)
1581{
1582 struct kmemleak_object *object;
1583 unsigned long flags;
1584
1585 rcu_read_lock();
1586 list_for_each_entry_rcu(object, &object_list, object_list) {
1587 spin_lock_irqsave(&object->lock, flags);
1588 if ((object->flags & OBJECT_REPORTED) &&
1589 unreferenced_object(object))
Luis R. Rodrigueza1084c82009-09-04 17:44:52 -07001590 __paint_it(object, KMEMLEAK_GREY);
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001591 spin_unlock_irqrestore(&object->lock, flags);
1592 }
1593 rcu_read_unlock();
Li Zefandc9b3f42014-04-03 14:46:26 -07001594
1595 kmemleak_found_leaks = false;
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001596}
1597
Li Zefanc89da702014-04-03 14:46:27 -07001598static void __kmemleak_do_cleanup(void);
1599
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001600/*
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001601 * File write operation to configure kmemleak at run-time. The following
1602 * commands can be written to the /sys/kernel/debug/kmemleak file:
1603 * off - disable kmemleak (irreversible)
1604 * stack=on - enable the task stacks scanning
1605 * stack=off - disable the tasks stacks scanning
1606 * scan=on - start the automatic memory scanning thread
1607 * scan=off - stop the automatic memory scanning thread
1608 * scan=... - set the automatic memory scanning period in seconds (0 to
1609 * disable it)
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001610 * scan - trigger a memory scan
Luis R. Rodriguez30b37102009-09-04 17:44:51 -07001611 * clear - mark all current reported unreferenced kmemleak objects as
Li Zefanc89da702014-04-03 14:46:27 -07001612 * grey to ignore printing them, or free all kmemleak objects
1613 * if kmemleak has been disabled.
Catalin Marinas189d84e2009-08-27 14:29:15 +01001614 * dump=... - dump information about the object found at the given address
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001615 */
1616static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
1617 size_t size, loff_t *ppos)
1618{
1619 char buf[64];
1620 int buf_size;
Catalin Marinasb87324d2009-07-07 10:32:58 +01001621 int ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001622
1623 buf_size = min(size, (sizeof(buf) - 1));
1624 if (strncpy_from_user(buf, user_buf, buf_size) < 0)
1625 return -EFAULT;
1626 buf[buf_size] = 0;
1627
Catalin Marinasb87324d2009-07-07 10:32:58 +01001628 ret = mutex_lock_interruptible(&scan_mutex);
1629 if (ret < 0)
1630 return ret;
1631
Li Zefanc89da702014-04-03 14:46:27 -07001632 if (strncmp(buf, "clear", 5) == 0) {
1633 if (atomic_read(&kmemleak_enabled))
1634 kmemleak_clear();
1635 else
1636 __kmemleak_do_cleanup();
1637 goto out;
1638 }
1639
1640 if (!atomic_read(&kmemleak_enabled)) {
1641 ret = -EBUSY;
1642 goto out;
1643 }
1644
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001645 if (strncmp(buf, "off", 3) == 0)
1646 kmemleak_disable();
1647 else if (strncmp(buf, "stack=on", 8) == 0)
1648 kmemleak_stack_scan = 1;
1649 else if (strncmp(buf, "stack=off", 9) == 0)
1650 kmemleak_stack_scan = 0;
1651 else if (strncmp(buf, "scan=on", 7) == 0)
1652 start_scan_thread();
1653 else if (strncmp(buf, "scan=off", 8) == 0)
1654 stop_scan_thread();
1655 else if (strncmp(buf, "scan=", 5) == 0) {
1656 unsigned long secs;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001657
Jingoo Han3dbb95f2013-09-11 14:20:25 -07001658 ret = kstrtoul(buf + 5, 0, &secs);
Catalin Marinasb87324d2009-07-07 10:32:58 +01001659 if (ret < 0)
1660 goto out;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001661 stop_scan_thread();
1662 if (secs) {
1663 jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
1664 start_scan_thread();
1665 }
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001666 } else if (strncmp(buf, "scan", 4) == 0)
1667 kmemleak_scan();
Catalin Marinas189d84e2009-08-27 14:29:15 +01001668 else if (strncmp(buf, "dump=", 5) == 0)
1669 ret = dump_str_object_info(buf + 5);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001670 else
Catalin Marinasb87324d2009-07-07 10:32:58 +01001671 ret = -EINVAL;
1672
1673out:
1674 mutex_unlock(&scan_mutex);
1675 if (ret < 0)
1676 return ret;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001677
1678 /* ignore the rest of the buffer, only one command at a time */
1679 *ppos += size;
1680 return size;
1681}
1682
1683static const struct file_operations kmemleak_fops = {
1684 .owner = THIS_MODULE,
1685 .open = kmemleak_open,
1686 .read = seq_read,
1687 .write = kmemleak_write,
1688 .llseek = seq_lseek,
Li Zefan5f3bf192014-04-03 14:46:28 -07001689 .release = seq_release,
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001690};
1691
Li Zefanc89da702014-04-03 14:46:27 -07001692static void __kmemleak_do_cleanup(void)
1693{
1694 struct kmemleak_object *object;
1695
1696 rcu_read_lock();
1697 list_for_each_entry_rcu(object, &object_list, object_list)
1698 delete_object_full(object->pointer);
1699 rcu_read_unlock();
1700}
1701
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001702/*
Catalin Marinas74341702011-09-29 11:50:07 +01001703 * Stop the memory scanning thread and free the kmemleak internal objects if
1704 * no previous scan thread (otherwise, kmemleak may still have some useful
1705 * information on memory leaks).
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001706 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001707static void kmemleak_do_cleanup(struct work_struct *work)
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001708{
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001709 mutex_lock(&scan_mutex);
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001710 stop_scan_thread();
1711
Li Zefanc89da702014-04-03 14:46:27 -07001712 if (!kmemleak_found_leaks)
1713 __kmemleak_do_cleanup();
1714 else
1715 pr_info("Kmemleak disabled without freeing internal data. "
1716 "Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\"\n");
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001717 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001718}
1719
Catalin Marinas179a8102009-09-07 10:14:42 +01001720static DECLARE_WORK(cleanup_work, kmemleak_do_cleanup);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001721
1722/*
1723 * Disable kmemleak. No memory allocation/freeing will be traced once this
1724 * function is called. Disabling kmemleak is an irreversible operation.
1725 */
1726static void kmemleak_disable(void)
1727{
1728 /* atomically check whether it was already invoked */
1729 if (atomic_cmpxchg(&kmemleak_error, 0, 1))
1730 return;
1731
1732 /* stop any memory operation tracing */
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001733 atomic_set(&kmemleak_enabled, 0);
1734
1735 /* check whether it is too early for a kernel thread */
1736 if (atomic_read(&kmemleak_initialized))
Catalin Marinas179a8102009-09-07 10:14:42 +01001737 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001738
1739 pr_info("Kernel memory leak detector disabled\n");
1740}
1741
1742/*
1743 * Allow boot-time kmemleak disabling (enabled by default).
1744 */
1745static int kmemleak_boot_config(char *str)
1746{
1747 if (!str)
1748 return -EINVAL;
1749 if (strcmp(str, "off") == 0)
1750 kmemleak_disable();
Jason Baronab0155a2010-07-19 11:54:17 +01001751 else if (strcmp(str, "on") == 0)
1752 kmemleak_skip_disable = 1;
1753 else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001754 return -EINVAL;
1755 return 0;
1756}
1757early_param("kmemleak", kmemleak_boot_config);
1758
Catalin Marinas5f790202011-09-28 12:17:03 +01001759static void __init print_log_trace(struct early_log *log)
1760{
1761 struct stack_trace trace;
1762
1763 trace.nr_entries = log->trace_len;
1764 trace.entries = log->trace;
1765
1766 pr_notice("Early log backtrace:\n");
1767 print_stack_trace(&trace, 2);
1768}
1769
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001770/*
Catalin Marinas20301172009-06-17 18:29:04 +01001771 * Kmemleak initialization.
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001772 */
1773void __init kmemleak_init(void)
1774{
1775 int i;
1776 unsigned long flags;
1777
Jason Baronab0155a2010-07-19 11:54:17 +01001778#ifdef CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF
1779 if (!kmemleak_skip_disable) {
Catalin Marinasb370d29e2012-01-20 10:42:40 +00001780 atomic_set(&kmemleak_early_log, 0);
Jason Baronab0155a2010-07-19 11:54:17 +01001781 kmemleak_disable();
1782 return;
1783 }
1784#endif
1785
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001786 jiffies_min_age = msecs_to_jiffies(MSECS_MIN_AGE);
1787 jiffies_scan_wait = msecs_to_jiffies(SECS_SCAN_WAIT * 1000);
1788
1789 object_cache = KMEM_CACHE(kmemleak_object, SLAB_NOLEAKTRACE);
1790 scan_area_cache = KMEM_CACHE(kmemleak_scan_area, SLAB_NOLEAKTRACE);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001791
Catalin Marinasb6693002011-09-28 17:22:56 +01001792 if (crt_early_log >= ARRAY_SIZE(early_log))
1793 pr_warning("Early log buffer exceeded (%d), please increase "
1794 "DEBUG_KMEMLEAK_EARLY_LOG_SIZE\n", crt_early_log);
1795
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001796 /* the kernel is still in UP mode, so disabling the IRQs is enough */
1797 local_irq_save(flags);
Catalin Marinasb6693002011-09-28 17:22:56 +01001798 atomic_set(&kmemleak_early_log, 0);
1799 if (atomic_read(&kmemleak_error)) {
1800 local_irq_restore(flags);
1801 return;
1802 } else
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001803 atomic_set(&kmemleak_enabled, 1);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001804 local_irq_restore(flags);
1805
1806 /*
1807 * This is the point where tracking allocations is safe. Automatic
1808 * scanning is started during the late initcall. Add the early logged
1809 * callbacks to the kmemleak infrastructure.
1810 */
1811 for (i = 0; i < crt_early_log; i++) {
1812 struct early_log *log = &early_log[i];
1813
1814 switch (log->op_type) {
1815 case KMEMLEAK_ALLOC:
Catalin Marinasfd678962009-08-27 14:29:17 +01001816 early_alloc(log);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001817 break;
Catalin Marinasf528f0b2011-09-26 17:12:53 +01001818 case KMEMLEAK_ALLOC_PERCPU:
1819 early_alloc_percpu(log);
1820 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001821 case KMEMLEAK_FREE:
1822 kmemleak_free(log->ptr);
1823 break;
Catalin Marinas53238a62009-07-07 10:33:00 +01001824 case KMEMLEAK_FREE_PART:
1825 kmemleak_free_part(log->ptr, log->size);
1826 break;
Catalin Marinasf528f0b2011-09-26 17:12:53 +01001827 case KMEMLEAK_FREE_PERCPU:
1828 kmemleak_free_percpu(log->ptr);
1829 break;
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001830 case KMEMLEAK_NOT_LEAK:
1831 kmemleak_not_leak(log->ptr);
1832 break;
1833 case KMEMLEAK_IGNORE:
1834 kmemleak_ignore(log->ptr);
1835 break;
1836 case KMEMLEAK_SCAN_AREA:
Catalin Marinasc017b4b2009-10-28 13:33:09 +00001837 kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001838 break;
1839 case KMEMLEAK_NO_SCAN:
1840 kmemleak_no_scan(log->ptr);
1841 break;
1842 default:
Catalin Marinas5f790202011-09-28 12:17:03 +01001843 kmemleak_warn("Unknown early log operation: %d\n",
1844 log->op_type);
1845 }
1846
1847 if (atomic_read(&kmemleak_warning)) {
1848 print_log_trace(log);
1849 atomic_set(&kmemleak_warning, 0);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001850 }
1851 }
1852}
1853
1854/*
1855 * Late initialization function.
1856 */
1857static int __init kmemleak_late_init(void)
1858{
1859 struct dentry *dentry;
1860
1861 atomic_set(&kmemleak_initialized, 1);
1862
1863 if (atomic_read(&kmemleak_error)) {
1864 /*
Lucas De Marchi25985ed2011-03-30 22:57:33 -03001865 * Some error occurred and kmemleak was disabled. There is a
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001866 * small chance that kmemleak_disable() was called immediately
1867 * after setting kmemleak_initialized and we may end up with
1868 * two clean-up threads but serialized by scan_mutex.
1869 */
Catalin Marinas179a8102009-09-07 10:14:42 +01001870 schedule_work(&cleanup_work);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001871 return -ENOMEM;
1872 }
1873
1874 dentry = debugfs_create_file("kmemleak", S_IRUGO, NULL, NULL,
1875 &kmemleak_fops);
1876 if (!dentry)
Joe Perchesae281062009-06-23 14:40:26 +01001877 pr_warning("Failed to create the debugfs kmemleak file\n");
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001878 mutex_lock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001879 start_scan_thread();
Catalin Marinas4698c1f2009-06-26 17:38:27 +01001880 mutex_unlock(&scan_mutex);
Catalin Marinas3c7b4e62009-06-11 13:22:39 +01001881
1882 pr_info("Kernel memory leak detector initialized\n");
1883
1884 return 0;
1885}
1886late_initcall(kmemleak_late_init);