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authorLinus Torvalds <torvalds@linux-foundation.org>2009-12-17 16:00:19 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-17 16:00:19 -0800
commitdcc7cd011220d7425a265c9bbf04c5731dacec1b (patch)
tree4c2244f6e6ce94e2698572e9d2df3baea8449c2a /mm
parentbf931a01a2c024a54204b4b02276af6e8d99a2c0 (diff)
parentb60e26a2f03d963f8c79ad7920d64abc4d38ecbc (diff)
downloadvexpress-lsk-dcc7cd011220d7425a265c9bbf04c5731dacec1b.tar.gz
Merge branch 'kmemleak' of git://linux-arm.org/linux-2.6
* 'kmemleak' of git://linux-arm.org/linux-2.6: kmemleak: fix kconfig for crc32 build error kmemleak: Reduce the false positives by checking for modified objects kmemleak: Show the age of an unreferenced object kmemleak: Release the object lock before calling put_object() kmemleak: Scan the _ftrace_events section in modules kmemleak: Simplify the kmemleak_scan_area() function prototype kmemleak: Do not use off-slab management with SLAB_NOLEAKTRACE
Diffstat (limited to 'mm')
-rw-r--r--mm/kmemleak.c188
-rw-r--r--mm/slab.c10
2 files changed, 107 insertions, 91 deletions
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 13f33b3081e..5b069e4f5e4 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -93,6 +93,7 @@
#include <linux/nodemask.h>
#include <linux/mm.h>
#include <linux/workqueue.h>
+#include <linux/crc32.h>
#include <asm/sections.h>
#include <asm/processor.h>
@@ -108,7 +109,6 @@
#define MSECS_MIN_AGE 5000 /* minimum object age for reporting */
#define SECS_FIRST_SCAN 60 /* delay before the first scan */
#define SECS_SCAN_WAIT 600 /* subsequent auto scanning delay */
-#define GRAY_LIST_PASSES 25 /* maximum number of gray list scans */
#define MAX_SCAN_SIZE 4096 /* maximum size of a scanned block */
#define BYTES_PER_POINTER sizeof(void *)
@@ -119,8 +119,8 @@
/* scanning area inside a memory block */
struct kmemleak_scan_area {
struct hlist_node node;
- unsigned long offset;
- size_t length;
+ unsigned long start;
+ size_t size;
};
#define KMEMLEAK_GREY 0
@@ -149,6 +149,8 @@ struct kmemleak_object {
int min_count;
/* the total number of pointers found pointing to this object */
int count;
+ /* checksum for detecting modified objects */
+ u32 checksum;
/* memory ranges to be scanned inside an object (empty for all) */
struct hlist_head area_list;
unsigned long trace[MAX_TRACE];
@@ -164,8 +166,6 @@ struct kmemleak_object {
#define OBJECT_REPORTED (1 << 1)
/* flag set to not scan the object */
#define OBJECT_NO_SCAN (1 << 2)
-/* flag set on newly allocated objects */
-#define OBJECT_NEW (1 << 3)
/* number of bytes to print per line; must be 16 or 32 */
#define HEX_ROW_SIZE 16
@@ -241,8 +241,6 @@ struct early_log {
const void *ptr; /* allocated/freed memory block */
size_t size; /* memory block size */
int min_count; /* minimum reference count */
- unsigned long offset; /* scan area offset */
- size_t length; /* scan area length */
unsigned long trace[MAX_TRACE]; /* stack trace */
unsigned int trace_len; /* stack trace length */
};
@@ -323,11 +321,6 @@ static bool color_gray(const struct kmemleak_object *object)
object->count >= object->min_count;
}
-static bool color_black(const struct kmemleak_object *object)
-{
- return object->min_count == KMEMLEAK_BLACK;
-}
-
/*
* Objects are considered unreferenced only if their color is white, they have
* not be deleted and have a minimum age to avoid false positives caused by
@@ -335,7 +328,7 @@ static bool color_black(const struct kmemleak_object *object)
*/
static bool unreferenced_object(struct kmemleak_object *object)
{
- return (object->flags & OBJECT_ALLOCATED) && color_white(object) &&
+ return (color_white(object) && object->flags & OBJECT_ALLOCATED) &&
time_before_eq(object->jiffies + jiffies_min_age,
jiffies_last_scan);
}
@@ -348,11 +341,13 @@ static void print_unreferenced(struct seq_file *seq,
struct kmemleak_object *object)
{
int i;
+ unsigned int msecs_age = jiffies_to_msecs(jiffies - object->jiffies);
seq_printf(seq, "unreferenced object 0x%08lx (size %zu):\n",
object->pointer, object->size);
- seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu\n",
- object->comm, object->pid, object->jiffies);
+ seq_printf(seq, " comm \"%s\", pid %d, jiffies %lu (age %d.%03ds)\n",
+ object->comm, object->pid, object->jiffies,
+ msecs_age / 1000, msecs_age % 1000);
hex_dump_object(seq, object);
seq_printf(seq, " backtrace:\n");
@@ -381,6 +376,7 @@ static void dump_object_info(struct kmemleak_object *object)
pr_notice(" min_count = %d\n", object->min_count);
pr_notice(" count = %d\n", object->count);
pr_notice(" flags = 0x%lx\n", object->flags);
+ pr_notice(" checksum = %d\n", object->checksum);
pr_notice(" backtrace:\n");
print_stack_trace(&trace, 4);
}
@@ -522,12 +518,13 @@ static struct kmemleak_object *create_object(unsigned long ptr, size_t size,
INIT_HLIST_HEAD(&object->area_list);
spin_lock_init(&object->lock);
atomic_set(&object->use_count, 1);
- object->flags = OBJECT_ALLOCATED | OBJECT_NEW;
+ object->flags = OBJECT_ALLOCATED;
object->pointer = ptr;
object->size = size;
object->min_count = min_count;
- object->count = -1; /* no color initially */
+ object->count = 0; /* white color initially */
object->jiffies = jiffies;
+ object->checksum = 0;
/* task information */
if (in_irq()) {
@@ -720,14 +717,13 @@ static void make_black_object(unsigned long ptr)
* Add a scanning area to the object. If at least one such area is added,
* kmemleak will only scan these ranges rather than the whole memory block.
*/
-static void add_scan_area(unsigned long ptr, unsigned long offset,
- size_t length, gfp_t gfp)
+static void add_scan_area(unsigned long ptr, size_t size, gfp_t gfp)
{
unsigned long flags;
struct kmemleak_object *object;
struct kmemleak_scan_area *area;
- object = find_and_get_object(ptr, 0);
+ object = find_and_get_object(ptr, 1);
if (!object) {
kmemleak_warn("Adding scan area to unknown object at 0x%08lx\n",
ptr);
@@ -741,7 +737,7 @@ static void add_scan_area(unsigned long ptr, unsigned long offset,
}
spin_lock_irqsave(&object->lock, flags);
- if (offset + length > object->size) {
+ if (ptr + size > object->pointer + object->size) {
kmemleak_warn("Scan area larger than object 0x%08lx\n", ptr);
dump_object_info(object);
kmem_cache_free(scan_area_cache, area);
@@ -749,8 +745,8 @@ static void add_scan_area(unsigned long ptr, unsigned long offset,
}
INIT_HLIST_NODE(&area->node);
- area->offset = offset;
- area->length = length;
+ area->start = ptr;
+ area->size = size;
hlist_add_head(&area->node, &object->area_list);
out_unlock:
@@ -786,7 +782,7 @@ static void object_no_scan(unsigned long ptr)
* processed later once kmemleak is fully initialized.
*/
static void __init log_early(int op_type, const void *ptr, size_t size,
- int min_count, unsigned long offset, size_t length)
+ int min_count)
{
unsigned long flags;
struct early_log *log;
@@ -808,8 +804,6 @@ static void __init log_early(int op_type, const void *ptr, size_t size,
log->ptr = ptr;
log->size = size;
log->min_count = min_count;
- log->offset = offset;
- log->length = length;
if (op_type == KMEMLEAK_ALLOC)
log->trace_len = __save_stack_trace(log->trace);
crt_early_log++;
@@ -858,7 +852,7 @@ void __ref kmemleak_alloc(const void *ptr, size_t size, int min_count,
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
create_object((unsigned long)ptr, size, min_count, gfp);
else if (atomic_read(&kmemleak_early_log))
- log_early(KMEMLEAK_ALLOC, ptr, size, min_count, 0, 0);
+ log_early(KMEMLEAK_ALLOC, ptr, size, min_count);
}
EXPORT_SYMBOL_GPL(kmemleak_alloc);
@@ -873,7 +867,7 @@ void __ref kmemleak_free(const void *ptr)
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
delete_object_full((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
- log_early(KMEMLEAK_FREE, ptr, 0, 0, 0, 0);
+ log_early(KMEMLEAK_FREE, ptr, 0, 0);
}
EXPORT_SYMBOL_GPL(kmemleak_free);
@@ -888,7 +882,7 @@ void __ref kmemleak_free_part(const void *ptr, size_t size)
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
delete_object_part((unsigned long)ptr, size);
else if (atomic_read(&kmemleak_early_log))
- log_early(KMEMLEAK_FREE_PART, ptr, size, 0, 0, 0);
+ log_early(KMEMLEAK_FREE_PART, ptr, size, 0);
}
EXPORT_SYMBOL_GPL(kmemleak_free_part);
@@ -903,7 +897,7 @@ void __ref kmemleak_not_leak(const void *ptr)
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
make_gray_object((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
- log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0, 0, 0);
+ log_early(KMEMLEAK_NOT_LEAK, ptr, 0, 0);
}
EXPORT_SYMBOL(kmemleak_not_leak);
@@ -919,22 +913,21 @@ void __ref kmemleak_ignore(const void *ptr)
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
make_black_object((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
- log_early(KMEMLEAK_IGNORE, ptr, 0, 0, 0, 0);
+ log_early(KMEMLEAK_IGNORE, ptr, 0, 0);
}
EXPORT_SYMBOL(kmemleak_ignore);
/*
* Limit the range to be scanned in an allocated memory block.
*/
-void __ref kmemleak_scan_area(const void *ptr, unsigned long offset,
- size_t length, gfp_t gfp)
+void __ref kmemleak_scan_area(const void *ptr, size_t size, gfp_t gfp)
{
pr_debug("%s(0x%p)\n", __func__, ptr);
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
- add_scan_area((unsigned long)ptr, offset, length, gfp);
+ add_scan_area((unsigned long)ptr, size, gfp);
else if (atomic_read(&kmemleak_early_log))
- log_early(KMEMLEAK_SCAN_AREA, ptr, 0, 0, offset, length);
+ log_early(KMEMLEAK_SCAN_AREA, ptr, size, 0);
}
EXPORT_SYMBOL(kmemleak_scan_area);
@@ -948,11 +941,25 @@ void __ref kmemleak_no_scan(const void *ptr)
if (atomic_read(&kmemleak_enabled) && ptr && !IS_ERR(ptr))
object_no_scan((unsigned long)ptr);
else if (atomic_read(&kmemleak_early_log))
- log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0, 0, 0);
+ log_early(KMEMLEAK_NO_SCAN, ptr, 0, 0);
}
EXPORT_SYMBOL(kmemleak_no_scan);
/*
+ * Update an object's checksum and return true if it was modified.
+ */
+static bool update_checksum(struct kmemleak_object *object)
+{
+ u32 old_csum = object->checksum;
+
+ if (!kmemcheck_is_obj_initialized(object->pointer, object->size))
+ return false;
+
+ object->checksum = crc32(0, (void *)object->pointer, object->size);
+ return object->checksum != old_csum;
+}
+
+/*
* Memory scanning is a long process and it needs to be interruptable. This
* function checks whether such interrupt condition occured.
*/
@@ -1031,11 +1038,14 @@ static void scan_block(void *_start, void *_end,
* added to the gray_list.
*/
object->count++;
- if (color_gray(object))
+ if (color_gray(object)) {
list_add_tail(&object->gray_list, &gray_list);
- else
- put_object(object);
+ spin_unlock_irqrestore(&object->lock, flags);
+ continue;
+ }
+
spin_unlock_irqrestore(&object->lock, flags);
+ put_object(object);
}
}
@@ -1075,14 +1085,47 @@ static void scan_object(struct kmemleak_object *object)
}
} else
hlist_for_each_entry(area, elem, &object->area_list, node)
- scan_block((void *)(object->pointer + area->offset),
- (void *)(object->pointer + area->offset
- + area->length), object, 0);
+ scan_block((void *)area->start,
+ (void *)(area->start + area->size),
+ object, 0);
out:
spin_unlock_irqrestore(&object->lock, flags);
}
/*
+ * Scan the objects already referenced (gray objects). More objects will be
+ * referenced and, if there are no memory leaks, all the objects are scanned.
+ */
+static void scan_gray_list(void)
+{
+ struct kmemleak_object *object, *tmp;
+
+ /*
+ * The list traversal is safe for both tail additions and removals
+ * from inside the loop. The kmemleak objects cannot be freed from
+ * outside the loop because their use_count was incremented.
+ */
+ object = list_entry(gray_list.next, typeof(*object), gray_list);
+ while (&object->gray_list != &gray_list) {
+ cond_resched();
+
+ /* may add new objects to the list */
+ if (!scan_should_stop())
+ scan_object(object);
+
+ tmp = list_entry(object->gray_list.next, typeof(*object),
+ gray_list);
+
+ /* remove the object from the list and release it */
+ list_del(&object->gray_list);
+ put_object(object);
+
+ object = tmp;
+ }
+ WARN_ON(!list_empty(&gray_list));
+}
+
+/*
* Scan data sections and all the referenced memory blocks allocated via the
* kernel's standard allocators. This function must be called with the
* scan_mutex held.
@@ -1090,10 +1133,9 @@ out:
static void kmemleak_scan(void)
{
unsigned long flags;
- struct kmemleak_object *object, *tmp;
+ struct kmemleak_object *object;
int i;
int new_leaks = 0;
- int gray_list_pass = 0;
jiffies_last_scan = jiffies;
@@ -1114,7 +1156,6 @@ static void kmemleak_scan(void)
#endif
/* reset the reference count (whiten the object) */
object->count = 0;
- object->flags &= ~OBJECT_NEW;
if (color_gray(object) && get_object(object))
list_add_tail(&object->gray_list, &gray_list);
@@ -1172,62 +1213,36 @@ static void kmemleak_scan(void)
/*
* Scan the objects already referenced from the sections scanned
- * above. More objects will be referenced and, if there are no memory
- * leaks, all the objects will be scanned. The list traversal is safe
- * for both tail additions and removals from inside the loop. The
- * kmemleak objects cannot be freed from outside the loop because their
- * use_count was increased.
+ * above.
*/
-repeat:
- object = list_entry(gray_list.next, typeof(*object), gray_list);
- while (&object->gray_list != &gray_list) {
- cond_resched();
-
- /* may add new objects to the list */
- if (!scan_should_stop())
- scan_object(object);
-
- tmp = list_entry(object->gray_list.next, typeof(*object),
- gray_list);
-
- /* remove the object from the list and release it */
- list_del(&object->gray_list);
- put_object(object);
-
- object = tmp;
- }
-
- if (scan_should_stop() || ++gray_list_pass >= GRAY_LIST_PASSES)
- goto scan_end;
+ scan_gray_list();
/*
- * Check for new objects allocated during this scanning and add them
- * to the gray list.
+ * Check for new or unreferenced objects modified since the previous
+ * scan and color them gray until the next scan.
*/
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list) {
spin_lock_irqsave(&object->lock, flags);
- if ((object->flags & OBJECT_NEW) && !color_black(object) &&
- get_object(object)) {
- object->flags &= ~OBJECT_NEW;
+ if (color_white(object) && (object->flags & OBJECT_ALLOCATED)
+ && update_checksum(object) && get_object(object)) {
+ /* color it gray temporarily */
+ object->count = object->min_count;
list_add_tail(&object->gray_list, &gray_list);
}
spin_unlock_irqrestore(&object->lock, flags);
}
rcu_read_unlock();
- if (!list_empty(&gray_list))
- goto repeat;
-
-scan_end:
- WARN_ON(!list_empty(&gray_list));
+ /*
+ * Re-scan the gray list for modified unreferenced objects.
+ */
+ scan_gray_list();
/*
- * If scanning was stopped or new objects were being allocated at a
- * higher rate than gray list scanning, do not report any new
- * unreferenced objects.
+ * If scanning was stopped do not report any new unreferenced objects.
*/
- if (scan_should_stop() || gray_list_pass >= GRAY_LIST_PASSES)
+ if (scan_should_stop())
return;
/*
@@ -1642,8 +1657,7 @@ void __init kmemleak_init(void)
kmemleak_ignore(log->ptr);
break;
case KMEMLEAK_SCAN_AREA:
- kmemleak_scan_area(log->ptr, log->offset, log->length,
- GFP_KERNEL);
+ kmemleak_scan_area(log->ptr, log->size, GFP_KERNEL);
break;
case KMEMLEAK_NO_SCAN:
kmemleak_no_scan(log->ptr);
diff --git a/mm/slab.c b/mm/slab.c
index 3f4822938f4..e17cc2c337b 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2275,9 +2275,11 @@ kmem_cache_create (const char *name, size_t size, size_t align,
/*
* Determine if the slab management is 'on' or 'off' slab.
* (bootstrapping cannot cope with offslab caches so don't do
- * it too early on.)
+ * it too early on. Always use on-slab management when
+ * SLAB_NOLEAKTRACE to avoid recursive calls into kmemleak)
*/
- if ((size >= (PAGE_SIZE >> 3)) && !slab_early_init)
+ if ((size >= (PAGE_SIZE >> 3)) && !slab_early_init &&
+ !(flags & SLAB_NOLEAKTRACE))
/*
* Size is large, assume best to place the slab management obj
* off-slab (should allow better packing of objs).
@@ -2596,8 +2598,8 @@ static struct slab *alloc_slabmgmt(struct kmem_cache *cachep, void *objp,
* kmemleak does not treat the ->s_mem pointer as a reference
* to the object. Otherwise we will not report the leak.
*/
- kmemleak_scan_area(slabp, offsetof(struct slab, list),
- sizeof(struct list_head), local_flags);
+ kmemleak_scan_area(&slabp->list, sizeof(struct list_head),
+ local_flags);
if (!slabp)
return NULL;
} else {