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Commit 95670001 authored by Anton Vorontsov's avatar Anton Vorontsov Committed by Greg Kroah-Hartman
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staging: android/lowmemorykiller: Better mm handling 



LMK should not directly check for task->mm. The reason is that the
process' threads may exit or detach its mm via use_mm(), but other
threads may still have a valid mm. To catch this we use
find_lock_task_mm(), which walks up all threads and returns an
appropriate task (with lock held).

Suggested-by: default avatarOleg Nesterov <oleg@redhat.com>
Reviewed-by: default avatarOleg Nesterov <oleg@redhat.com>
Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 294b2711

drivers/staging/android/lowmemorykiller.c

+9 −7
Original line number Diff line number Diff line
@@ -82,7 +82,7 @@ task_notify_func(struct notifier_block *self, unsigned long val, void *data) 


static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc)

{

	struct task_struct *p;

	struct task_struct *tsk;

	struct task_struct *selected = NULL;

	int rem = 0;

	int tasksize;
@@ -134,15 +134,17 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) 
	selected_oom_adj = min_adj;



	rcu_read_lock();

	for_each_process(p) {

		struct mm_struct *mm;

	for_each_process(tsk) {

		struct task_struct *p;

		struct signal_struct *sig;

		int oom_adj;



		task_lock(p);

		mm = p->mm;

		p = find_lock_task_mm(tsk);

		if (!p)

			continue;



		sig = p->signal;

		if (!mm || !sig) {

		if (!sig) {

			task_unlock(p);

			continue;

		}
@@ -151,7 +153,7 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) 
			task_unlock(p);

			continue;

		}

		tasksize = get_mm_rss(mm);

		tasksize = get_mm_rss(p->mm);

		task_unlock(p);

		if (tasksize <= 0)

			continue;