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kmemleak: allow freeing internal objects after kmemleak was disabled

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Currently if kmemleak is disabled, the kmemleak objects can never be
freed, no matter if it's disabled by a user or due to fatal errors.

Those objects can be a big waste of memory.

    OBJS ACTIVE  USE OBJ SIZE  SLABS OBJ/SLAB CACHE SIZE NAME
  1200264 1197433  99%    0.30K  46164       26    369312K kmemleak_object

With this patch, after kmemleak was disabled you can reclaim memory
with:

	# echo clear > /sys/kernel/debug/kmemleak

Also inform users about this with a printk.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Li Zefan
2014-04-03 14:46:27 -07:00
committed by Linus Torvalds
parent dc9b3f4249
commit c89da70c73
2 changed files with 46 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files
mm/kmemleak.c
+32 -14
View File
@@ -1600,6 +1600,8 @@ static void kmemleak_clear(void)
kmemleak_found_leaks = false;
}
static void __kmemleak_do_cleanup(void);
/*
* File write operation to configure kmemleak at run-time. The following
* commands can be written to the /sys/kernel/debug/kmemleak file:
@@ -1612,7 +1614,8 @@ static void kmemleak_clear(void)
* disable it)
* scan - trigger a memory scan
* clear - mark all current reported unreferenced kmemleak objects as
* grey to ignore printing them
* grey to ignore printing them, or free all kmemleak objects
* if kmemleak has been disabled.
* dump=... - dump information about the object found at the given address
*/
static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
@@ -1622,9 +1625,6 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
int buf_size;
int ret;
if (!atomic_read(&kmemleak_enabled))
return -EBUSY;
buf_size = min(size, (sizeof(buf) - 1));
if (strncpy_from_user(buf, user_buf, buf_size) < 0)
return -EFAULT;
@@ -1634,6 +1634,19 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
if (ret < 0)
return ret;
if (strncmp(buf, "clear", 5) == 0) {
if (atomic_read(&kmemleak_enabled))
kmemleak_clear();
else
__kmemleak_do_cleanup();
goto out;
}
if (!atomic_read(&kmemleak_enabled)) {
ret = -EBUSY;
goto out;
}
if (strncmp(buf, "off", 3) == 0)
kmemleak_disable();
else if (strncmp(buf, "stack=on", 8) == 0)
@@ -1657,8 +1670,6 @@ static ssize_t kmemleak_write(struct file *file, const char __user *user_buf,
}
} else if (strncmp(buf, "scan", 4) == 0)
kmemleak_scan();
else if (strncmp(buf, "clear", 5) == 0)
kmemleak_clear();
else if (strncmp(buf, "dump=", 5) == 0)
ret = dump_str_object_info(buf + 5);
else
@@ -1683,6 +1694,16 @@ static const struct file_operations kmemleak_fops = {
.release = kmemleak_release,
};
static void __kmemleak_do_cleanup(void)
{
struct kmemleak_object *object;
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list)
delete_object_full(object->pointer);
rcu_read_unlock();
}
/*
* Stop the memory scanning thread and free the kmemleak internal objects if
* no previous scan thread (otherwise, kmemleak may still have some useful
@@ -1690,17 +1711,14 @@ static const struct file_operations kmemleak_fops = {
*/
static void kmemleak_do_cleanup(struct work_struct *work)
{
struct kmemleak_object *object;
mutex_lock(&scan_mutex);
stop_scan_thread();
if (!kmemleak_found_leaks) {
rcu_read_lock();
list_for_each_entry_rcu(object, &object_list, object_list)
delete_object_full(object->pointer);
rcu_read_unlock();
}
if (!kmemleak_found_leaks)
__kmemleak_do_cleanup();
else
pr_info("Kmemleak disabled without freeing internal data. "
"Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\"\n");
mutex_unlock(&scan_mutex);
}