linux-kernel - Re: [PATCH 0/2 v4] oom: capture unreclaimable slab info in oom message when kernel panic

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: <20170925142352.havlx6ikheanqyhj@dhcp22.suse.cz>
Date:   Mon, 25 Sep 2017 16:23:52 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Yang Shi <yang.s@...baba-inc.com>
Cc:     cl@...ux.com, penberg@...nel.org, rientjes@...gle.com,
        iamjoonsoo.kim@....com, akpm@...ux-foundation.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2 v4] oom: capture unreclaimable slab info in oom
 message when kernel panic

On Thu 21-09-17 06:38:50, Yang Shi wrote:
> Recently we ran into a oom issue, kernel panic due to no killable process.
> The dmesg shows huge unreclaimable slabs used almost 100% memory, but kdump doesn't capture vmcore due to some reason.
> 
> So, it may sound better to capture unreclaimable slab info in oom message when kernel panic to aid trouble shooting and cover the corner case.
> Since kernel already panic, so capturing more information sounds worthy and doesn't bother normal oom killer.
> 
> With the patchset, tools/vm/slabinfo has a new option, "-U", to show unreclaimable slab only.
> 
> And, oom will print all non zero (num_objs * size != 0) unreclaimable slabs in oom killer message.

Well, I do undestand that this _might_ be useful but it also might
generates a _lot_ of output. The oom report can be quite verbose already
so is this something we want to have enabled by default?
-- 
Michal Hocko
SUSE Labs