linux-kernel - Re: [PATCH v4 2/4] mm/oom: handle remote ooms

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <YZiCgrTzcl/QQC+N@casper.infradead.org>
Date:   Sat, 20 Nov 2021 05:07:14 +0000
From:   Matthew Wilcox <willy@...radead.org>
To:     Mina Almasry <almasrymina@...gle.com>
Cc:     Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jonathan Corbet <corbet@....net>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Hugh Dickins <hughd@...gle.com>, Shuah Khan <shuah@...nel.org>,
        Shakeel Butt <shakeelb@...gle.com>,
        Greg Thelen <gthelen@...gle.com>,
        Dave Chinner <david@...morbit.com>,
        Roman Gushchin <guro@...com>, Theodore Ts'o <tytso@....edu>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, cgroups@...r.kernel.org
Subject: Re: [PATCH v4 2/4] mm/oom: handle remote ooms

On Fri, Nov 19, 2021 at 08:50:08PM -0800, 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. The oom-killer may be
> unable to find a process to kill if there are no killable processes in
> the remote memcg. In this case, the oom-killer (out_of_memory()) will return
> false, and depending on the gfp, that will generally get bubbled up to
> mem_cgroup_charge_mapping() as an ENOMEM.

Why doesn't it try to run the shrinkers to get back some page cache /
slab cache memory from this memcg?  I understand it might not be able
to (eg if the memory is mlocked), but surely that's rare.