kmemleak: allow freeing internal objects after kmemleak was disabled (c89da70c) · Commits · 戴 / test

Documentation/kmemleak.txt

+14 −1

Original line number	Diff line number	Diff line
		@@ -53,7 +53,8 @@ Memory scanning parameters can be modified at run-time by writing to the
		(default 600, 0 to stop the automatic scanning)
		scan - trigger a memory scan
		clear - clear list of current memory leak suspects, done by
		marking all current reported unreferenced objects grey
		marking all current reported unreferenced objects grey,
		or free all kmemleak objects if kmemleak has been disabled.
		dump=<addr> - dump information about the object found at <addr>

		Kmemleak can also be disabled at boot-time by passing "kmemleak=off" on
		@@ -120,6 +121,18 @@ Then as usual to get your report with:

		# cat /sys/kernel/debug/kmemleak

		Freeing kmemleak internal objects
		---------------------------------

		To allow access to previosuly found memory leaks after kmemleak has been
		disabled by the user or due to an fatal error, internal kmemleak objects
		won't be freed when kmemleak is disabled, and those objects may occupy
		a large part of physical memory.

		In this situation, you may reclaim memory with:

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

		Kmemleak API
		------------

mm/kmemleak.c

+32 −14

Original line number	Diff line number	Diff line
		@@ -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);
		}

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