Hi,

On Sun, 2012-11-25 at 14:11 +0100, Ben Hutchings wrote:

On Wed, 2012-11-14 at 20:11 -0800, Greg Kroah-Hartman wrote:

quoted

3.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Benjamin Marzinski <bmarzins@redhat.com>

commit 96e5d1d3adf56f1c7eeb07258f6a1a0a7ae9c489 upstream.

In gfs2_trans_add_bh(), gfs2 was testing if a there was a bd attached to the
buffer without having the gfs2_log_lock held. It was then assuming it would
stay attached for the rest of the function. However, without either the log
lock being held of the buffer locked, __gfs2_ail_flush() could detach bd at any
time.  This patch moves the locking before the test.  If there isn't a bd
already attached, gfs2 can safely allocate one and attach it before locking.
There is no way that the newly allocated bd could be on the ail list,
and thus no way for __gfs2_ail_flush() to detach it.

Signed-off-by: Benjamin Marzinski <bmarzins@redhat.com>
Signed-off-by: Steven Whitehouse <redacted>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

[...]

Is this needed for any earlier versions?  It looks applicable to 3.2
(with minor changes).

Ben.

Potentially yes, although I don't think we've had any reports from that
far back,

Steve.