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Date: Wed, 01 Jun 2011 21:34:24 +0900 (JST)
Message-Id: <20110601.213424.80025869.anemo@mba.ocn.ne.jp>
To: James.Bottomley@HansenPartnership.com, Jens Axboe <axboe@kernel.dk>
Cc: greg@kroah.com, mjt@tls.msk.ru, jslaby@suse.cz, stable@kernel.org,
        jejb@parisc-linux.org, linux-kernel@vger.kernel.org
Subject: Re: [stable] apparent regression (crash) - 2.6.38.6
From: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
In-Reply-To: <1305776367.2576.0.camel@mulgrave.site>
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On Thu, 19 May 2011 07:39:27 +0400, James Bottomley <James.Bottomley@HansenPartnership.com> wrote:
> On Wed, 2011-05-18 at 17:25 -0700, Greg KH wrote:
> > On Wed, May 11, 2011 at 12:34:51PM -0700, Greg KH wrote:
> > > On Wed, May 11, 2011 at 02:19:17PM -0500, James Bottomley wrote:
> > > > > > [  106.994628] BUG: unable to handle kernel NULL pointer dereference at 0000000000000048
> > > > > > [  106.994755] IP: [<ffffffff811bec1b>] elv_queue_empty+0x1b/0x30
> > > > 
> > > > Hmm, it's another missing elevator guard, like this patch:
> > > > 
> > > > http://marc.info/?l=linux-scsi&m=130348673628282
> > > > 
> > > > I think the bug here is that q->elevator is null, so dereferencing
> > > > elevator->ops gives the bug.
> > > 
> > > Is this patch going to Linus anytime soon?
> > 
> > Ping?
> 
> I pinged Jens about it yesterday; he said it should be on its way to
> Linus.

The patch in above URL ("block: add proper state guards to
__elv_next_request") is in mainline and stable-queues now, but how
about a similar fix for elv_queue_empty()?

The elv_queue_empty() is removed in mainline, but it seems
stable-2.6.38.x and prior stable-branches still need the fix for
elv_queue_empty().

---
Atsushi Nemoto
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