linux-kernel - Re: [PATCH v3 1/2] mm: introduce process

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: <CALvZod4M6mF3VvAdade3n5fE1E0LQp+CeJHWLc+pHmZqqAhepg@mail.gmail.com>
Date:   Mon, 26 Jul 2021 06:43:50 -0700
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Michal Hocko <mhocko@...e.com>
Cc:     Suren Baghdasaryan <surenb@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Rientjes <rientjes@...gle.com>,
        Matthew Wilcox <willy@...radead.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Roman Gushchin <guro@...com>, Rik van Riel <riel@...riel.com>,
        Minchan Kim <minchan@...nel.org>,
        Christian Brauner <christian@...uner.io>,
        Christoph Hellwig <hch@...radead.org>,
        Oleg Nesterov <oleg@...hat.com>,
        David Hildenbrand <david@...hat.com>,
        Jann Horn <jannh@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Florian Weimer <fweimer@...hat.com>,
        Jan Engelhardt <jengelh@...i.de>,
        Tim Murray <timmurray@...gle.com>,
        Linux API <linux-api@...r.kernel.org>,
        Linux MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-team <kernel-team@...roid.com>
Subject: Re: [PATCH v3 1/2] mm: introduce process_mrelease system call

On Mon, Jul 26, 2021 at 12:27 AM Michal Hocko <mhocko@...e.com> wrote:
>
[...]
>
> Is process_mrelease on all of them really necessary? I thought that the
> primary reason for the call is to guarantee a forward progress in cases
> where the userspace OOM victim cannot die on SIGKILL. That should be
> more an exception than a normal case, no?
>

I am thinking of using this API in this way: On user-defined OOM
condition, kill a job/cgroup and unconditionally reap all of its
processes. Keep monitoring the situation and if it does not improve go
for another kill and reap.

I can add additional logic in between kill and reap to see if reap is
necessary but unconditionally reaping is more simple.

>
> > An alternative would be to have a cgroup specific interface for
> > reaping similar to cgroup.kill.
>
> Could you elaborate?
>

I mentioned this in [1] where I was thinking if it makes sense to
overload cgroup.kill to also add the SIGKILLed processes in
oom_reaper_list. The downside would be that there will be one thread
doing the reaping and the syscall approach allows userspace to reap in
multiple threads. I think for now, I would go with whatever Suren is
proposing and we can always add more stuff if need arises.

[1] https://lore.kernel.org/containers/CALvZod4jsb6bFzTOS4ZRAJGAzBru0oWanAhezToprjACfGm+ew@mail.gmail.com/