From: Al Viro <viro@ZenIV.linux.org.uk>
To: Jari Ruusu <jariruusu@users.sourceforge.net>
Cc: linux-kernel@vger.kernel.org,
Rusty Russell <rusty@rustcorp.com.au>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: 2.6.35-rc2 module reference counting broken
Date: Mon, 7 Jun 2010 07:44:12 +0100 [thread overview]
Message-ID: <20100607064412.GK31073@ZenIV.linux.org.uk> (raw)
In-Reply-To: <4C0C819E.EA5D6A18@users.sourceforge.net>
On Mon, Jun 07, 2010 at 08:20:30AM +0300, Jari Ruusu wrote:
> Someone broke block device module reference counting. Problem occours when a
> modular block device is mounted and unmounted. Not when it is directly read.
> 2.6.34 kernel works OK, but 2.6.35-rc2 kernel seems to increase usage count
> by one for each mount + umount pair.
Very interesting... Looks like mount() bumps refcount by 2. umount() after
that drops refcount by 1, so it's not leaking superblocks.
Which probably means that open_bdev_exclusive() is fscked. Interesting...
FWIW, quick look through the history seems to point to this:
commit 6b4517a7913a09d3259bb1d21c9cb300f12294bd
Author: Tejun Heo <tj@kernel.org>
Date: Wed Apr 7 18:53:59 2010 +0900
block: implement bd_claiming and claiming block
I'm far too sleepy right now, but I'd start with reviewing what that
thing is doing to module refcounting...
next prev parent reply other threads:[~2010-06-07 6:44 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-07 5:20 2.6.35-rc2 module reference counting broken Jari Ruusu
2010-06-07 6:44 ` Al Viro [this message]
2010-06-08 23:48 ` Al Viro
2010-06-09 7:01 ` Tejun Heo
2010-06-10 6:34 ` Jari Ruusu
2010-06-10 11:31 ` Tejun Heo
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