Commit dabca8de authored by Liam Mark's avatar Liam Mark
Browse files

android/lowmemorykiller: Check all tasks for death pending 



The lowmemorykiller uses the TIF_MEMDIE flag to help ensure it doesn't
kill another task until the memory from the previously killed task has
been returned to the system.

However the lowmemorykiller does not currently look at tasks who do not
have a tasks->mm, but just because a process doesn't have a tasks->mm
does not mean that the task's memory has been fully returned to the
system yet.

In order to prevent the lowmemorykiller from unnecessarily killing
multiple applications in a row the lowmemorykiller has been changed to
ensure that previous killed tasks are no longer in the process list
before attempting to kill another task.

Change-Id: I7d8a8fd39ca5625e6448ed2efebfb621f6e93845
Signed-off-by: default avatarLiam Mark <lmark@codeaurora.org>
parent ba0482e6

drivers/staging/android/lowmemorykiller.c

+23 −6
Original line number Diff line number Diff line
@@ -62,6 +62,22 @@ static unsigned long lowmem_deathpending_timeout; 
			printk(x);			\

	} while (0)



static int test_task_flag(struct task_struct *p, int flag)

{

	struct task_struct *t = p;



	do {

		task_lock(t);

		if (test_tsk_thread_flag(t, flag)) {

			task_unlock(t);

			return 1;

		}

		task_unlock(t);

	} while_each_thread(p, t);



	return 0;

}



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

{

	struct task_struct *tsk;
@@ -111,16 +127,17 @@ static int lowmem_shrink(struct shrinker *s, struct shrink_control *sc) 
		if (tsk->flags & PF_KTHREAD)

			continue;



		if (time_before_eq(jiffies, lowmem_deathpending_timeout)) {

			if (test_task_flag(tsk, TIF_MEMDIE)) {

				rcu_read_unlock();

				return 0;

			}

		}



		p = find_lock_task_mm(tsk);

		if (!p)

			continue;



		if (test_tsk_thread_flag(p, TIF_MEMDIE) &&

		    time_before_eq(jiffies, lowmem_deathpending_timeout)) {

			task_unlock(p);

			rcu_read_unlock();

			return 0;

		}

		oom_score_adj = p->signal->oom_score_adj;

		if (oom_score_adj < min_score_adj) {

			task_unlock(p);