[PATCH] OOM: thaw the OOM victim if it is frozen

[Michal Hocko]

oom_kill_process only sets TIF_MEMDIE flag and sends a signal to the
victim. This is basically noop when the task is frozen though because
the task sleeps in uninterruptible sleep. The victim is eventually
thawed later when oom_scan_process_thread meets the task again in a
later OOM invocation so the OOM killer doesn't live lock. But this is
less than optimal. Let's add __thaw_task into mark_tsk_oom_victim after
we set TIF_MEMDIE to the victim. We are not checking whether the task is
frozen because that would be racy and __thaw_task does that already.
oom_scan_process_thread doesn't need to care about freezer anymore
as TIF_MEMDIE and freezer are excluded completely now.

Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
---
 mm/oom_kill.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 56eab9621c3a..19a08f3f00ba 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -266,8 +266,6 @@ enum oom_scan_t oom_scan_process_thread(struct task_struct *task,
 	 * Don't allow any other task to have access to the reserves.
 	 */
 	if (test_tsk_thread_flag(task, TIF_MEMDIE)) {
-		if (unlikely(frozen(task)))
-			__thaw_task(task);
 		if (!force_kill)
 			return OOM_SCAN_ABORT;
 	}
@@ -428,6 +426,7 @@ void note_oom_kill(void)
 void mark_tsk_oom_victim(struct task_struct *tsk)
 {
 	set_tsk_thread_flag(tsk, TIF_MEMDIE);
+	__thaw_task(tsk);
 }
 
 /**
-- 
2.1.3


-- 
Michal Hocko
SUSE Labs
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/