linux-kernel - Re: [patch 2/4] vfs: add set_page_dirty

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, 17 Feb 2009 11:05:16 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Nick Piggin <npiggin@...e.de>
Cc:	Edward Shishkin <edward.shishkin@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Ryan Hope <rmh3093@...il.com>,
	Randy Dunlap <randy.dunlap@...cle.com>,
	linux-kernel@...r.kernel.org,
	ReiserFS Mailing List <reiserfs-devel@...r.kernel.org>
Subject: Re: [patch 2/4] vfs: add set_page_dirty_notag

On Tue, 2009-02-17 at 10:38 +0100, Nick Piggin wrote:

> It is a great shame that filesystems are not properly notified
> that a page may become dirty before the actual set_page_dirty
> event (which is not allowed to fail and is called after the
> page is already dirty).

Not quite true, for example the set_page_dirty() done by the write fault
code is done _before_ the page becomes dirty.

This before/after thing was the reason for that horrid file corruption
bug that dragged on for a few weeks back in .19 (IIRC).

> This is a big problem I have with fsblock simply in trying to
> make the memory allocation robust. page_mkwrite unfortunately
> is racy and I've fixed problems there... the big problem though
> is get_user_pages. Fixing that properly seems to require fixing
> callers so it is not really realistic in the short term.

Right, I'm just not sure what we can do, even with a
prepage_page_dirty() function, what are you going to do, fail the fault?

--
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/