Re: [PATCH 2/2] oom-clear-tif_memdie-after-oom_reaper-managed-to-unmap-the-address-space-fix

From: Johannes Weiner
Date: Wed Mar 09 2016 - 17:30:17 EST

On Wed, Mar 09, 2016 at 01:21:42PM -0800, Andrew Morton wrote:
> I found the below patch lying around but I didn't queue it properly.
> Is it legit?

Yeah. Michal suggested this should be its own patch, which I agree
with. The subject would then be:

Subject: mm: oom_kill: don't ignore oom score on exiting tasks

> From: Johannes Weiner <hannes@xxxxxxxxxxx>
> Subject: oom-clear-tif_memdie-after-oom_reaper-managed-to-unmap-the-address-space-fix
> When the OOM killer scans tasks and encounters a PF_EXITING one, it
> force-selects that one regardless of the score. Is there a possibility
> that the task might hang after it has set PF_EXITING? In that case the
> OOM killer should be able to move on to the next task.
> Frankly, I don't even know why we check for exiting tasks in the OOM
> killer. We've tried direct reclaim at least 15 times by the time we
> decide the system is OOM, there was plenty of time to exit and free
> memory; and a task might exit voluntarily right after we issue a kill.
> This is testing pure noise.

Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>