linux-kernel - Re: [workqueue] WARNING: CPU: 0 PID: 76 at drivers/block/floppy.c:968 schedule

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Message-ID: <alpine.LNX.2.00.1407081656290.1655@pobox.suse.cz>
Date:	Tue, 8 Jul 2014 16:56:57 +0200 (CEST)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Tejun Heo <tj@...nel.org>
cc:	Fengguang Wu <fengguang.wu@...el.com>,
	Jet Chen <jet.chen@...el.com>, Su Tao <tao.su@...el.com>,
	Yuanhan Liu <yuanhan.liu@...el.com>, LKP <lkp@...org>,
	linux-kernel@...r.kernel.org
Subject: Re: [workqueue] WARNING: CPU: 0 PID: 76 at drivers/block/floppy.c:968
 schedule_bh()

On Tue, 8 Jul 2014, Tejun Heo wrote:

> > Hmmm... this is schedule_bh() in floppy.c complaining that the work
> > item is already pending.  The cond_resched() addition by b22ce2785d97
> > doesn't change the semantics around work item execution although it
> > could have exposed an existing problem in the floppy driver.  I'll
> > look into how this could happen.
> 
> It doesn't reproduce here and nothing really stands out to me.  It
> probably involves floppy_work requeueing itself and something else
> getting executed inbetween which wouldn't have happend before, but I
> can't figure out what that could be and either can I follow the
> control flow the driver. :)
>
> 
> Jiri, any ideas?

I will take a look. Could this be a bad bisect though due to this actually 
being a race condition perhaps?

-- 
Jiri Kosina
SUSE Labs
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