From: "Theodore Ts'o" <tytso@mit.edu>
To: Tony Luck <tony.luck@gmail.com>
Cc: eunb.song@samsung.com, Dmitry Monakhov <dmonakhov@openvz.org>,
"linux-ext4@vger.kernel.org" <linux-ext4@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: EXT4 panic at jbd2_journal_put_journal_head() in 3.9+
Date: Sun, 12 May 2013 23:36:55 -0400 [thread overview]
Message-ID: <20130513033655.GE25996@thunk.org> (raw)
In-Reply-To: <CA+8MBb+51dMaYQd-g-T40+UstbxsSbmewSXiUfNDrVouSA3=Zw@mail.gmail.com>
On Sun, May 12, 2013 at 08:11:59PM -0700, Tony Luck wrote:
>
> My best guess as to why this commit causes problems is that there are places
> where updates to individual fields in this structure used to be independent
> because they were to whole words. Now we have bitfileds there are races
> between access to different fields in the same word.
Yeah, except we access the fields while holding a lock.... wait a
minute. We're using bit_spinlocks().... and am I missing something?
Where are the barrier statements to prevent the CPU or the compiler
from reordering statements around bit_spin_lock()? But if that's the
problem, I would have expected lots of other things to be broken.
- Ted
next prev parent reply other threads:[~2013-05-13 3:37 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-05-13 2:21 Re: Re: EXT4 panic at jbd2_journal_put_journal_head() in 3.9+ EUNBONG SONG
2013-05-13 3:11 ` Tony Luck
2013-05-13 3:36 ` Theodore Ts'o [this message]
2013-05-13 5:18 ` Mike Galbraith
2013-05-13 6:14 ` Tony Luck
-- strict thread matches above, loose matches on Subject: below --
2013-05-10 0:51 EUNBONG SONG
2013-05-10 17:27 ` Tony Luck
2013-05-11 7:52 ` Dmitry Monakhov
2013-05-13 2:04 ` Tony Luck
2013-05-13 3:07 ` Theodore Ts'o
2013-05-13 5:06 ` Sidorov, Andrei
2013-05-10 19:27 ` Theodore Ts'o
2013-05-10 20:38 ` David Daney
2013-05-09 7:59 EUNBONG SONG
2013-05-09 15:31 ` Theodore Ts'o
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