linux-kernel - Re: [patch 1/5] mm: add nofail variants of kmalloc kcalloc and kzalloc

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: <1282740778.2605.3652.camel@laptop>
Date:	Wed, 25 Aug 2010 14:52:58 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Ted Ts'o <tytso@....edu>
Cc:	David Rientjes <rientjes@...gle.com>,
	Jens Axboe <jaxboe@...ionio.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Neil Brown <neilb@...e.de>, Alasdair G Kergon <agk@...hat.com>,
	Chris Mason <chris.mason@...cle.com>,
	Steven Whitehouse <swhiteho@...hat.com>,
	Jan Kara <jack@...e.cz>,
	Frederic Weisbecker <fweisbec@...il.com>,
	"linux-raid@...r.kernel.org" <linux-raid@...r.kernel.org>,
	"linux-btrfs@...r.kernel.org" <linux-btrfs@...r.kernel.org>,
	"cluster-devel@...hat.com" <cluster-devel@...hat.com>,
	"linux-ext4@...r.kernel.org" <linux-ext4@...r.kernel.org>,
	"reiserfs-devel@...r.kernel.org" <reiserfs-devel@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [patch 1/5] mm: add nofail variants of kmalloc kcalloc and
 kzalloc

On Wed, 2010-08-25 at 14:48 +0200, Peter Zijlstra wrote:

> > > On Wed, 2010-08-25 at 07:24 -0400, Ted Ts'o wrote:

> > > > (a) retry the loop in the jbd layer (which Andrew really doesn't
> > > > like), (b) keep our own private cache of free memory so we don't fail
> > > > and/or loop, 

> Well (b) sounds a lot saner than either of those. Simply revert to a
> state that is sub-optimal but has bounded memory use and reserve that
> memory up-front. That way you can always get out of a tight memory spot.

Also, there's a good reason for disliking (a), its a deadlock scenario,
suppose we need to write out data to get free pages, but the writing out
is blocked on requiring free pages.

There's really nothing the page allocator can do to help you there, its
a situation you have to avoid getting into.


--
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/