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authorLinus Torvalds <torvalds@linux-foundation.org>2009-06-30 19:04:53 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-06-30 19:04:53 -0700
commite83c2b0ff325f52dda1aff3572d0e1516216c54b (patch)
tree0d9dd56df33a308d03c8ac2d666826017777f0cf /mm
parent9fcfc91bda04259abb9af2fd83bbf48d19da8502 (diff)
parent12de38b186c2af97bf0b4a1f907f766df46b1def (diff)
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Merge branch 'kmemleak' of git://linux-arm.org/linux-2.6
* 'kmemleak' of git://linux-arm.org/linux-2.6: kmemleak: Inform kmemleak about pid_hash kmemleak: Do not warn if an unknown object is freed kmemleak: Do not report new leaked objects if the scanning was stopped kmemleak: Slightly change the policy on newly allocated objects kmemleak: Do not trigger a scan when reading the debug/kmemleak file kmemleak: Simplify the reports logged by the scanning thread kmemleak: Enable task stacks scanning by default kmemleak: Allow the early log buffer to be configurable.
Diffstat (limited to 'mm')
-rw-r--r--mm/kmemleak.c166
1 files changed, 70 insertions, 96 deletions
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index c96f2c8700aa..eeece2deace2 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -48,10 +48,10 @@
* scanned. This list is only modified during a scanning episode when the
* scan_mutex is held. At the end of a scan, the gray_list is always empty.
* Note that the kmemleak_object.use_count is incremented when an object is
- * added to the gray_list and therefore cannot be freed
- * - kmemleak_mutex (mutex): prevents multiple users of the "kmemleak" debugfs
- * file together with modifications to the memory scanning parameters
- * including the scan_thread pointer
+ * added to the gray_list and therefore cannot be freed. This mutex also
+ * prevents multiple users of the "kmemleak" debugfs file together with
+ * modifications to the memory scanning parameters including the scan_thread
+ * pointer
*
* The kmemleak_object structures have a use_count incremented or decremented
* using the get_object()/put_object() functions. When the use_count becomes
@@ -190,15 +190,15 @@ static unsigned long max_addr;
static unsigned long next_scan_yield;
static struct task_struct *scan_thread;
static unsigned long jiffies_scan_yield;
+/* used to avoid reporting of recently allocated objects */
static unsigned long jiffies_min_age;
+static unsigned long jiffies_last_scan;
/* delay between automatic memory scannings */
static signed long jiffies_scan_wait;
/* enables or disables the task stacks scanning */
-static int kmemleak_stack_scan;
-/* mutex protecting the memory scanning */
+static int kmemleak_stack_scan = 1;
+/* protects the memory scanning, parameters and debug/kmemleak file access */
static DEFINE_MUTEX(scan_mutex);
-/* mutex protecting the access to the /sys/kernel/debug/kmemleak file */
-static DEFINE_MUTEX(kmemleak_mutex);
/* number of leaks reported (for limitation purposes) */
static int reported_leaks;
@@ -235,7 +235,7 @@ struct early_log {
};
/* early logging buffer and current position */
-static struct early_log early_log[200];
+static struct early_log early_log[CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE];
static int crt_early_log;
static void kmemleak_disable(void);
@@ -279,15 +279,6 @@ static int color_gray(const struct kmemleak_object *object)
}
/*
- * Objects are considered referenced if their color is gray and they have not
- * been deleted.
- */
-static int referenced_object(struct kmemleak_object *object)
-{
- return (object->flags & OBJECT_ALLOCATED) && color_gray(object);
-}
-
-/*
* 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
* pointers temporarily stored in CPU registers.
@@ -295,42 +286,28 @@ static int referenced_object(struct kmemleak_object *object)
static int unreferenced_object(struct kmemleak_object *object)
{
return (object->flags & OBJECT_ALLOCATED) && color_white(object) &&
- time_is_before_eq_jiffies(object->jiffies + jiffies_min_age);
+ time_before_eq(object->jiffies + jiffies_min_age,
+ jiffies_last_scan);
}
/*
- * Printing of the (un)referenced objects information, either to the seq file
- * or to the kernel log. The print_referenced/print_unreferenced functions
- * must be called with the object->lock held.
+ * Printing of the unreferenced objects information to the seq file. The
+ * print_unreferenced function must be called with the object->lock held.
*/
-#define print_helper(seq, x...) do { \
- struct seq_file *s = (seq); \
- if (s) \
- seq_printf(s, x); \
- else \
- pr_info(x); \
-} while (0)
-
-static void print_referenced(struct kmemleak_object *object)
-{
- pr_info("referenced object 0x%08lx (size %zu)\n",
- object->pointer, object->size);
-}
-
static void print_unreferenced(struct seq_file *seq,
struct kmemleak_object *object)
{
int i;
- print_helper(seq, "unreferenced object 0x%08lx (size %zu):\n",
- object->pointer, object->size);
- print_helper(seq, " comm \"%s\", pid %d, jiffies %lu\n",
- object->comm, object->pid, object->jiffies);
- print_helper(seq, " backtrace:\n");
+ 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, " backtrace:\n");
for (i = 0; i < object->trace_len; i++) {
void *ptr = (void *)object->trace[i];
- print_helper(seq, " [<%p>] %pS\n", ptr, ptr);
+ seq_printf(seq, " [<%p>] %pS\n", ptr, ptr);
}
}
@@ -554,8 +531,10 @@ static void delete_object(unsigned long ptr)
write_lock_irqsave(&kmemleak_lock, flags);
object = lookup_object(ptr, 0);
if (!object) {
+#ifdef DEBUG
kmemleak_warn("Freeing unknown object at 0x%08lx\n",
ptr);
+#endif
write_unlock_irqrestore(&kmemleak_lock, flags);
return;
}
@@ -571,8 +550,6 @@ static void delete_object(unsigned long ptr)
* cannot be freed when it is being scanned.
*/
spin_lock_irqsave(&object->lock, flags);
- if (object->flags & OBJECT_REPORTED)
- print_referenced(object);
object->flags &= ~OBJECT_ALLOCATED;
spin_unlock_irqrestore(&object->lock, flags);
put_object(object);
@@ -696,7 +673,8 @@ static void log_early(int op_type, const void *ptr, size_t size,
struct early_log *log;
if (crt_early_log >= ARRAY_SIZE(early_log)) {
- kmemleak_stop("Early log buffer exceeded\n");
+ pr_warning("Early log buffer exceeded\n");
+ kmemleak_disable();
return;
}
@@ -952,6 +930,9 @@ static void kmemleak_scan(void)
struct kmemleak_object *object, *tmp;
struct task_struct *task;
int i;
+ int new_leaks = 0;
+
+ jiffies_last_scan = jiffies;
/* prepare the kmemleak_object's */
rcu_read_lock();
@@ -1049,6 +1030,32 @@ static void kmemleak_scan(void)
object = tmp;
}
WARN_ON(!list_empty(&gray_list));
+
+ /*
+ * If scanning was stopped do not report any new unreferenced objects.
+ */
+ if (scan_should_stop())
+ return;
+
+ /*
+ * Scanning result reporting.
+ */
+ rcu_read_lock();
+ list_for_each_entry_rcu(object, &object_list, object_list) {
+ spin_lock_irqsave(&object->lock, flags);
+ if (unreferenced_object(object) &&
+ !(object->flags & OBJECT_REPORTED)) {
+ object->flags |= OBJECT_REPORTED;
+ new_leaks++;
+ }
+ spin_unlock_irqrestore(&object->lock, flags);
+ }
+ rcu_read_unlock();
+
+ if (new_leaks)
+ pr_info("%d new suspected memory leaks (see "
+ "/sys/kernel/debug/kmemleak)\n", new_leaks);
+
}
/*
@@ -1070,36 +1077,12 @@ static int kmemleak_scan_thread(void *arg)
}
while (!kthread_should_stop()) {
- struct kmemleak_object *object;
signed long timeout = jiffies_scan_wait;
mutex_lock(&scan_mutex);
-
kmemleak_scan();
- reported_leaks = 0;
-
- rcu_read_lock();
- list_for_each_entry_rcu(object, &object_list, object_list) {
- unsigned long flags;
-
- if (reported_leaks >= REPORTS_NR)
- break;
- spin_lock_irqsave(&object->lock, flags);
- if (!(object->flags & OBJECT_REPORTED) &&
- unreferenced_object(object)) {
- print_unreferenced(NULL, object);
- object->flags |= OBJECT_REPORTED;
- reported_leaks++;
- } else if ((object->flags & OBJECT_REPORTED) &&
- referenced_object(object)) {
- print_referenced(object);
- object->flags &= ~OBJECT_REPORTED;
- }
- spin_unlock_irqrestore(&object->lock, flags);
- }
- rcu_read_unlock();
-
mutex_unlock(&scan_mutex);
+
/* wait before the next scan */
while (timeout && !kthread_should_stop())
timeout = schedule_timeout_interruptible(timeout);
@@ -1112,7 +1095,7 @@ static int kmemleak_scan_thread(void *arg)
/*
* Start the automatic memory scanning thread. This function must be called
- * with the kmemleak_mutex held.
+ * with the scan_mutex held.
*/
void start_scan_thread(void)
{
@@ -1127,7 +1110,7 @@ void start_scan_thread(void)
/*
* Stop the automatic memory scanning thread. This function must be called
- * with the kmemleak_mutex held.
+ * with the scan_mutex held.
*/
void stop_scan_thread(void)
{
@@ -1147,10 +1130,8 @@ static void *kmemleak_seq_start(struct seq_file *seq, loff_t *pos)
struct kmemleak_object *object;
loff_t n = *pos;
- if (!n) {
- kmemleak_scan();
+ if (!n)
reported_leaks = 0;
- }
if (reported_leaks >= REPORTS_NR)
return NULL;
@@ -1211,11 +1192,10 @@ static int kmemleak_seq_show(struct seq_file *seq, void *v)
unsigned long flags;
spin_lock_irqsave(&object->lock, flags);
- if (!unreferenced_object(object))
- goto out;
- print_unreferenced(seq, object);
- reported_leaks++;
-out:
+ if ((object->flags & OBJECT_REPORTED) && unreferenced_object(object)) {
+ print_unreferenced(seq, object);
+ reported_leaks++;
+ }
spin_unlock_irqrestore(&object->lock, flags);
return 0;
}
@@ -1234,13 +1214,10 @@ static int kmemleak_open(struct inode *inode, struct file *file)
if (!atomic_read(&kmemleak_enabled))
return -EBUSY;
- ret = mutex_lock_interruptible(&kmemleak_mutex);
+ ret = mutex_lock_interruptible(&scan_mutex);
if (ret < 0)
goto out;
if (file->f_mode & FMODE_READ) {
- ret = mutex_lock_interruptible(&scan_mutex);
- if (ret < 0)
- goto kmemleak_unlock;
ret = seq_open(file, &kmemleak_seq_ops);
if (ret < 0)
goto scan_unlock;
@@ -1249,8 +1226,6 @@ static int kmemleak_open(struct inode *inode, struct file *file)
scan_unlock:
mutex_unlock(&scan_mutex);
-kmemleak_unlock:
- mutex_unlock(&kmemleak_mutex);
out:
return ret;
}
@@ -1259,11 +1234,9 @@ static int kmemleak_release(struct inode *inode, struct file *file)
{
int ret = 0;
- if (file->f_mode & FMODE_READ) {
+ if (file->f_mode & FMODE_READ)
seq_release(inode, file);
- mutex_unlock(&scan_mutex);
- }
- mutex_unlock(&kmemleak_mutex);
+ mutex_unlock(&scan_mutex);
return ret;
}
@@ -1278,6 +1251,7 @@ static int kmemleak_release(struct inode *inode, struct file *file)
* scan=off - stop the automatic memory scanning thread
* scan=... - set the automatic memory scanning period in seconds (0 to
* disable it)
+ * scan - trigger a memory scan
*/
static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
size_t size, loff_t *ppos)
@@ -1315,7 +1289,9 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
jiffies_scan_wait = msecs_to_jiffies(secs * 1000);
start_scan_thread();
}
- } else
+ } else if (strncmp(buf, "scan", 4) == 0)
+ kmemleak_scan();
+ else
return -EINVAL;
/* ignore the rest of the buffer, only one command at a time */
@@ -1340,11 +1316,9 @@ static int kmemleak_cleanup_thread(void *arg)
{
struct kmemleak_object *object;
- mutex_lock(&kmemleak_mutex);
+ mutex_lock(&scan_mutex);
stop_scan_thread();
- mutex_unlock(&kmemleak_mutex);
- mutex_lock(&scan_mutex);
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list)
delete_object(object->pointer);
@@ -1486,9 +1460,9 @@ static int __init kmemleak_late_init(void)
&kmemleak_fops);
if (!dentry)
pr_warning("Failed to create the debugfs kmemleak file\n");
- mutex_lock(&kmemleak_mutex);
+ mutex_lock(&scan_mutex);
start_scan_thread();
- mutex_unlock(&kmemleak_mutex);
+ mutex_unlock(&scan_mutex);
pr_info("Kernel memory leak detector initialized\n");