linux-kernel - Re: [PATCH] mm/oom_kill.c: don't kill TASK

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Date:	Fri, 18 Sep 2015 12:00:59 -0500 (CDT)
From:	Christoph Lameter <cl@...ux.com>
To:	Oleg Nesterov <oleg@...hat.com>
cc:	Kyle Walker <kwalker@...hat.com>, akpm@...ux-foundation.org,
	mhocko@...e.cz, rientjes@...gle.com, hannes@...xchg.org,
	vdavydov@...allels.com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	Stanislav Kozina <skozina@...hat.com>
Subject: Re: [PATCH] mm/oom_kill.c: don't kill TASK_UNINTERRUPTIBLE tasks

On Fri, 18 Sep 2015, Oleg Nesterov wrote:

> To simplify the discussion lets ignore PF_FROZEN, this is another issue.

Ok.

Subject: Allow multiple kills from the OOM killer

The OOM killer currently aborts if it finds a process that already is having
access to the reserve memory pool for exit processing. This is done so that
the reserves are not overcommitted but on the other hand this also allows
only one process being oom killed at the time. That process may be stuck
in D state.

Signed-off-by: Christoph Lameter <cl@...ux.com>

Index: linux/mm/oom_kill.c
===================================================================
--- linux.orig/mm/oom_kill.c	2015-09-18 11:58:52.963946782 -0500
+++ linux/mm/oom_kill.c	2015-09-18 11:59:42.010684778 -0500
@@ -264,10 +264,9 @@ enum oom_scan_t oom_scan_process_thread(
 	 * This task already has access to memory reserves and is being killed.
 	 * Don't allow any other task to have access to the reserves.
 	 */
-	if (test_tsk_thread_flag(task, TIF_MEMDIE)) {
-		if (oc->order != -1)
-			return OOM_SCAN_ABORT;
-	}
+	if (test_tsk_thread_flag(task, TIF_MEMDIE))
+		return OOM_SCAN_CONTINUE;
+
 	if (!task->mm)
 		return OOM_SCAN_CONTINUE;

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