linux-kernel - Re: [PATCH 3/3] mlock: avoid dirtying pages and triggering writeback

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: <20101118133702.GA18834@infradead.org>
Date:	Thu, 18 Nov 2010 08:37:02 -0500
From:	Christoph Hellwig <hch@...radead.org>
To:	Dave Chinner <david@...morbit.com>
Cc:	Michel Lespinasse <walken@...gle.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Nick Piggin <npiggin@...nel.dk>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>,
	Rik van Riel <riel@...hat.com>,
	Kosaki Motohiro <kosaki.motohiro@...fujitsu.com>,
	Theodore Tso <tytso@...gle.com>,
	Michael Rubin <mrubin@...gle.com>,
	Suleiman Souhlal <suleiman@...gle.com>
Subject: Re: [PATCH 3/3] mlock: avoid dirtying pages and triggering writeback

On Thu, Nov 18, 2010 at 10:11:43AM +1100, Dave Chinner wrote:
> Hence I think that avoiding ->page_mkwrite callouts is likely to
> break some filesystems in subtle, undetected ways.  IMO, regardless
> of what is done, it would be really good to start by writing a new
> regression test to exercise and encode the expected the mlock
> behaviour so we can detect regressions later on....

I think it would help if we could drink a bit of the test driven design
coolaid here. Michel, can you write some testcases where pages on a
shared mapping are mlocked, then dirtied and then munlocked, and then
written out using msync/fsync.  Anything that fails this test on
btrfs/ext4/gfs/xfs/etc obviously doesn't work.

--
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/