From: Tejun Heo <tj@kernel.org>
To: Vivek Goyal <vgoyal@redhat.com>
Cc: Shaohua Li <shaohua.li@intel.com>,
linux kernel mailing list <linux-kernel@vger.kernel.org>,
Jens Axboe <axboe@kernel.dk>
Subject: Re: Kernel crash in icq_free_icq_rcu
Date: Wed, 18 Jan 2012 08:09:57 -0800 [thread overview]
Message-ID: <20120118160957.GB30664@google.com> (raw)
In-Reply-To: <20120118142005.GC30204@redhat.com>
On Wed, Jan 18, 2012 at 09:20:05AM -0500, Vivek Goyal wrote:
> > Not allocating icq if request is never going to go to elevator as elevator
> > switch was happening makes sense to me.
> >
> > I tried this patch. It went little further and crashed at a different
> > place. I think this seems to be separate merging issue Tejun is trying
> > to track down.
>
> Applied Tejun's debug patch to return early and not call into elevator
> for checking whether merge is allowed or not. Things seems to be stable
> now for me.
Yeah, plug merge is calling into elevator code without any
synchronization, so it's bound to be broken. Given plugging is
per-task, I don't think we really need to query elevator about merging
bio's. The request is not on elevator and plugging is part of issuing
mechanism, not scheduling, after all. Jens, what do you think?
Thanks.
--
tejun
next prev parent reply other threads:[~2012-01-18 16:10 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-17 20:18 Kernel crash in icq_free_icq_rcu Vivek Goyal
2012-01-17 20:19 ` Jens Axboe
2012-01-17 20:40 ` Vivek Goyal
2012-01-17 20:42 ` Jens Axboe
2012-01-17 20:58 ` Vivek Goyal
2012-01-17 21:01 ` Vivek Goyal
2012-01-17 21:48 ` Tejun Heo
2012-01-17 22:07 ` Vivek Goyal
2012-01-18 1:01 ` Shaohua Li
2012-01-18 1:03 ` Tejun Heo
2012-01-18 1:05 ` Shaohua Li
2012-01-18 1:11 ` Tejun Heo
2012-01-18 1:30 ` Shaohua Li
2012-01-18 2:26 ` Shaohua Li
2012-01-18 4:23 ` Shaohua Li
2012-01-18 6:03 ` Shaohua Li
2012-01-18 13:51 ` Vivek Goyal
2012-01-18 14:20 ` Vivek Goyal
2012-01-18 16:09 ` Tejun Heo [this message]
2012-01-18 16:24 ` Jens Axboe
2012-01-18 16:31 ` Jens Axboe
2012-01-18 16:36 ` Vivek Goyal
2012-01-18 17:10 ` Tejun Heo
2012-01-18 19:07 ` Jens Axboe
2012-01-18 19:05 ` Jens Axboe
2012-01-18 16:55 ` Tejun Heo
2012-01-18 16:07 ` Tejun Heo
2012-01-19 1:41 ` [patch]block: fix NULL icq_cache reference Shaohua Li
2012-01-19 1:43 ` Tejun Heo
2012-01-19 8:20 ` Jens Axboe
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