On Fri 08-01-16 22:14:54, Tetsuo Handa wrote:

Michal Hocko wrote:

quoted

On Thu 07-01-16 11:28:15, Johannes Weiner wrote:

quoted

On Tue, Dec 29, 2015 at 10:58:22PM +0900, Tetsuo Handa wrote:

quoted

quoted

From 8bb9e36891a803e82c589ef78077838026ce0f7d Mon Sep 17 00:00:00 2001

From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: Tue, 29 Dec 2015 22:20:58 +0900
Subject: [PATCH] mm,oom: Exclude TIF_MEMDIE processes from candidates.

The OOM reaper kernel thread can reclaim OOM victim's memory before the victim
terminates. But since oom_kill_process() tries to kill children of the memory
hog process first, the OOM reaper can not reclaim enough memory for terminating
the victim if the victim is consuming little memory. The result is OOM livelock
as usual, for timeout based next OOM victim selection is not implemented.

What we should be doing is have the OOM reaper clear TIF_MEMDIE after
it's done. There is no reason to wait for and prioritize the exit of a
task that doesn't even have memory anymore. Once a task's memory has
been reaped, subsequent OOM invocations should evaluate anew the most
desirable OOM victim.

This is an interesting idea. It definitely sounds better than timeout
based solutions. I will cook up a patch for this. The API between oom
killer and the reaper has to change slightly but that shouldn't be a big
deal.

That is part of what I suggested at
http://lkml.kernel.org/r/201512052133.IAE00551.LSOQFtMFFVOHOJ@I-love.SAKURA.ne.jp .
| What about marking current OOM victim unkillable by updating
| victim->signal->oom_score_adj to OOM_SCORE_ADJ_MIN and clearing victim's
| TIF_MEMDIE flag when the victim is still alive for a second after
| oom_reap_vmas() completed?

Sorry, I must have missed this part. I have added your Suggested-by to the
patch description.

Can we update victim's oom_score_adj as well? Otherwise, the OOM killer
might choose the same victim if victim's oom_score_adj was set to 1000.

Yes I've done that in the patch I am testing ATM.

-- 
Michal Hocko
SUSE Labs

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