linux-kernel - Re: [PATCH] fs, mm: account filp and names caches to kmemcg

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]

Date:   Tue, 24 Oct 2017 11:45:11 -0400
From:   Johannes Weiner <hannes@...xchg.org>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     Greg Thelen <gthelen@...gle.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux MM <linux-mm@...ck.org>, linux-fsdevel@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fs, mm: account filp and names caches to kmemcg

On Fri, Oct 13, 2017 at 08:35:55AM +0200, Michal Hocko wrote:
> On Thu 12-10-17 15:03:12, Johannes Weiner wrote:
> > All I'm saying is that, when the syscall-context fails to charge, we
> > should do mem_cgroup_oom() to set up the async OOM killer, let the
> > charge succeed over the hard limit - since the OOM killer will most
> > likely get us back below the limit - then mem_cgroup_oom_synchronize()
> > before the syscall returns to userspace.
> 
> OK, then we are on the same page now. Your initial wording didn't
> mention async OOM killer. This makes more sense. Although I would argue
> that we can retry the charge as long as out_of_memory finds a victim.
> This would return ENOMEM to the pathological cases where no victims
> could be found.

I think that's much worse because it's even harder to test and verify
your applications against.

If syscalls can return -ENOMEM on OOM, they should do so reliably.