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Commit 29c696e1 authored by Vladimir Davydov's avatar Vladimir Davydov Committed by Linus Torvalds
Browse files

oom: make oom_reaper_list single linked 



Entries are only added/removed from oom_reaper_list at head so we can
use a single linked list and hence save a word in task_struct.

Signed-off-by: default avatarVladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 855b0183

include/linux/sched.h

+1 −1
Original line number Diff line number Diff line
@@ -1852,7 +1852,7 @@ struct task_struct { 
#endif

	int pagefault_disabled;

#ifdef CONFIG_MMU

	struct list_head oom_reaper_list;

	struct task_struct *oom_reaper_list;

#endif

/* CPU-specific state of this task */

	struct thread_struct thread;

mm/oom_kill.c

+7 −8
Original line number Diff line number Diff line
@@ -419,7 +419,7 @@ bool oom_killer_disabled __read_mostly; 
 */

static struct task_struct *oom_reaper_th;

static DECLARE_WAIT_QUEUE_HEAD(oom_reaper_wait);

static LIST_HEAD(oom_reaper_list);

static struct task_struct *oom_reaper_list;

static DEFINE_SPINLOCK(oom_reaper_lock);
@@ -528,13 +528,11 @@ static int oom_reaper(void *unused) 
	while (true) {

		struct task_struct *tsk = NULL;



		wait_event_freezable(oom_reaper_wait,

				     (!list_empty(&oom_reaper_list)));

		wait_event_freezable(oom_reaper_wait, oom_reaper_list != NULL);

		spin_lock(&oom_reaper_lock);

		if (!list_empty(&oom_reaper_list)) {

			tsk = list_first_entry(&oom_reaper_list,

					struct task_struct, oom_reaper_list);

			list_del(&tsk->oom_reaper_list);

		if (oom_reaper_list != NULL) {

			tsk = oom_reaper_list;

			oom_reaper_list = tsk->oom_reaper_list;

		}

		spin_unlock(&oom_reaper_lock);
@@ -553,7 +551,8 @@ static void wake_oom_reaper(struct task_struct *tsk) 
	get_task_struct(tsk);



	spin_lock(&oom_reaper_lock);

	list_add(&tsk->oom_reaper_list, &oom_reaper_list);

	tsk->oom_reaper_list = oom_reaper_list;

	oom_reaper_list = tsk;

	spin_unlock(&oom_reaper_lock);

	wake_up(&oom_reaper_wait);

}