linux-ext4 - Re: [PATCH 3/3] ext4: Fix deadlock when writing in ENOSPC conditions

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] [day] [month] [year] [list]

Message-ID: <20131218054559.GC19434@thunk.org>
Date:	Wed, 18 Dec 2013 00:45:59 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	Jan Kara <jack@...e.cz>
Cc:	Akira Fujita <a-fujita@...jp.nec.com>, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 3/3] ext4: Fix deadlock when writing in ENOSPC conditions

On Tue, Dec 10, 2013 at 11:14:00AM +0100, Jan Kara wrote:
> Akira-san has been reporting rare deadlocks of his machine when running
> xfstests test 269 on ext4 filesystem. The problem turned out to be in
> ext4_da_reserve_metadata() and ext4_da_reserve_space() which called
> ext4_should_retry_alloc() while holding i_data_sem. Since
> ext4_should_retry_alloc() can force a transaction commit, this is a
> lock ordering violation and leads to deadlocks.
> 
> Fix the problem by just removing the retry loops. These functions should
> just report ENOSPC to the caller (e.g. ext4_da_write_begin()) and that
> function must take care of retrying after dropping all necessary locks.
> 
> Reported-and-tested-by: Akira Fujita <a-fujita@...jp.nec.com>
> Signed-off-by: Jan Kara <jack@...e.cz>

Thanks, applied.

					- Ted
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html