linux-kernel - Re: [PATCH] Repeated fork() causes SLAB to grow without bound

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: <546DFFA1.4030700@redhat.com>
Date:	Thu, 20 Nov 2014 09:50:09 -0500
From:	Rik van Riel <riel@...hat.com>
To:	Konstantin Khlebnikov <koct9i@...il.com>,
	Michel Lespinasse <walken@...gle.com>
CC:	Vlastimil Babka <vbabka@...e.cz>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Tim Hartrick <tim@...ecast.com>, Michal Hocko <mhocko@...e.cz>
Subject: Re: [PATCH] Repeated fork() causes SLAB to grow without bound

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 11/20/2014 09:42 AM, Konstantin Khlebnikov wrote:

> I'm thinking about limitation for reusing anon_vmas which might
> increase performance without breaking asymptotic estimation of
> count anon_vma in the worst case. For example this heuristic: allow
> to reuse only anon_vma with single direct descendant. It seems
> there will be arount up to two times more anon_vmas but
> false-aliasing must be much lower.

It may even be possible to not create a child anon_vma for the
first child a parent forks, but only create a new anon_vma once
the parent clones a second child (alive at the same time as the
first child).

That still takes care of things like apache or sendmail, but
would not create infinite anon_vmas for a task that keeps forking
itself to infinite depth without calling exec...

- -- 
All rights reversed
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1

iQEcBAEBAgAGBQJUbf+hAAoJEM553pKExN6DxhQH/1QL+9GdhaSx7EQnRcbDRcHi
GuEfMU0g9Kv4ad+oPSQnH/L7vJMJAYeh5ZJGH+rOykWHp3sGReqDZOnzpXRAe11z
1cSC1BJsndzrv9wX8niFpuKpYbF0IP+ckv3qaEzWtm5yCRyhHVZfr6b794Y4K9jF
z2EPPu1vAAldbkx1VlYTwofBA5lESL5UmrFvH4ouI7BeWYSEe6BgVCbvK+K5fANT
ketdA5R08xyUAcXDa+28qpBYkdWnxNhwqseDoXCW8SOFNwWbLDI6GRfrsCNku13i
Gi41h3uEuIAGDf+AU/GMjiymgwutCOGq+cfZlszELaRvHmDpNGYdPv1llghNg7Q=
=Vk+H
-----END PGP SIGNATURE-----
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/