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Commit 4f1cdd2b authored by Liam Mark's avatar Liam Mark Committed by Vinayak Menon
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android/lowmemorykiller: Ignore tasks with freed mm 



A killed task can stay in the task list long after its
memory has been returned to the system, therefore
ignore any tasks whose mm struct has been freed.

Change-Id: I76394b203b4ab2312437c839976f0ecb7b6dde4e
Signed-off-by: default avatarLiam Mark <lmark@codeaurora.org>
Signed-off-by: default avatarVinayak Menon <vinmenon@codeaurora.org>
parent 11a71a36

arch/arm/include/asm/thread_info.h

+1 −0
Original line number Diff line number Diff line
@@ -148,6 +148,7 @@ extern int vfp_restore_user_hwstate(struct user_vfp __user *, 
#define TIF_USING_IWMMXT	17

#define TIF_MEMDIE		18	/* is terminating due to OOM killer */

#define TIF_RESTORE_SIGMASK	20

#define TIF_MM_RELEASED	21	/* task MM has been released */



#define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)

#define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)

arch/um/include/asm/thread_info.h

+1 −0
Original line number Diff line number Diff line
@@ -63,6 +63,7 @@ static inline struct thread_info *current_thread_info(void) 
#define TIF_RESTORE_SIGMASK	7

#define TIF_NOTIFY_RESUME	8

#define TIF_SECCOMP		9	/* secure computing */

#define TIF_MM_RELEASED         10	/* task MM has been released */



#define _TIF_SYSCALL_TRACE	(1 << TIF_SYSCALL_TRACE)

#define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)

drivers/staging/android/lowmemorykiller.c

+23 −2
Original line number Diff line number Diff line
@@ -83,6 +83,22 @@ static unsigned long lowmem_count(struct shrinker *s, 
		global_node_page_state(NR_INACTIVE_FILE);

}



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 test_task_lmk_waiting(struct task_struct *p)

{

	struct task_struct *t = p;
@@ -158,6 +174,10 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc) 
		if (tsk->flags & PF_KTHREAD)

			continue;



		/* if task no longer has any memory ignore it */

		if (test_task_flag(tsk, TIF_MM_RELEASED))

			continue;



		if (time_before_eq(jiffies, lowmem_deathpending_timeout)) {

			if (test_task_lmk_waiting(tsk)) {

				rcu_read_unlock();
@@ -218,13 +238,14 @@ static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc) 
			     free);

		lowmem_deathpending_timeout = jiffies + HZ;

		rem += selected_tasksize;

		rcu_read_unlock();

		/* give the system time to free up the memory */

		msleep_interruptible(20);

	}

	} else

		rcu_read_unlock();



	lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n",

		     sc->nr_to_scan, sc->gfp_mask, rem);

	rcu_read_unlock();

	mutex_unlock(&scan_mutex);

	return rem;

}

include/linux/sched.h

+1 −1
Original line number Diff line number Diff line
@@ -3217,7 +3217,7 @@ static inline bool mmget_not_zero(struct mm_struct *mm) 
}



/* mmput gets rid of the mappings and all user-space */

extern void mmput(struct mm_struct *);

extern int mmput(struct mm_struct *mm);

#ifdef CONFIG_MMU

/* same as above but performs the slow path from the async context. Can

 * be called from the atomic context as well

kernel/exit.c

+5 −1
Original line number Diff line number Diff line
@@ -465,6 +465,7 @@ static void exit_mm(struct task_struct *tsk) 
{

	struct mm_struct *mm = tsk->mm;

	struct core_state *core_state;

	int mm_released;



	mm_release(tsk, mm);

	if (!mm)
@@ -511,9 +512,12 @@ static void exit_mm(struct task_struct *tsk) 
	enter_lazy_tlb(mm, current);

	task_unlock(tsk);

	mm_update_next_owner(mm);

	mmput(mm);



	mm_released = mmput(mm);

	if (test_thread_flag(TIF_MEMDIE))

		exit_oom_victim();

	if (mm_released)

		set_tsk_thread_flag(tsk, TIF_MM_RELEASED);

}



static struct task_struct *find_alive_thread(struct task_struct *p)