From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>
Subject: Re: [PATCH v3 2/4] mm/oom: handle remote ooms
Date: Fri, 12 Nov 2021 08:51:56 +0100
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To: Mina Almasry <almasrymina-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
Cc: Theodore Ts'o <tytso-3s7WtUTddSA@public.gmane.org>, Greg Thelen <gthelen-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>, Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>, Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>, Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>, Vladimir Davydov <vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, Muchun Song <songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>, riel-ebMLmSuQjDVBDgjK7y7TUQ@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org

On Thu 11-11-21 15:42:01, Mina Almasry wrote:
> On remote ooms (OOMs due to remote charging), the oom-killer will attempt
> to find a task to kill in the memcg under oom, if the oom-killer
> is unable to find one, the oom-killer should simply return ENOMEM to the
> allocating process.

This really begs for some justification.

> If we're in pagefault path and we're unable to return ENOMEM to the
> allocating process, we instead kill the allocating process.

Why do you handle those differently?

> Signed-off-by: Mina Almasry <almasrymina-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> 
> Cc: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>
> Cc: Theodore Ts'o <tytso-3s7WtUTddSA@public.gmane.org>
> Cc: Greg Thelen <gthelen-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> Cc: Shakeel Butt <shakeelb-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
> Cc: Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> CC: Roman Gushchin <guro-b10kYP2dOMg@public.gmane.org>
> Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
> Cc: Hugh Dickins <hughd-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
> Cc: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Cc: Vladimir Davydov <vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Cc: Muchun Song <songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org>
> Cc: riel-ebMLmSuQjDVBDgjK7y7TUQ@public.gmane.org
> Cc: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org
> Cc: linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
-- 
Michal Hocko
SUSE Labs