linux-kernel - Re: [Workqueue] crash in process_one

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Message-ID: <20141008121502.GA8184@htj.dyndns.org>
Date:	Wed, 8 Oct 2014 08:15:02 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Arun KS <getarunks@...il.com>
Cc:	Arun KS <arunks.linux@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	laijs@...fujitsu.com, Silesh C V <saileshcv@...il.com>
Subject: Re: [Workqueue] crash in process_one_work

Hello, Arun.

On Wed, Oct 08, 2014 at 05:30:20PM +0530, Arun KS wrote:
> > I sure hope not.  How reproducible is the issue?  Can you try w/
> > CONFIG_DEBUG_OBJECTS_WORK enabled?
> 
> Thanks for replying.
> That was a problem with one of our driver. It was freeing the
> memory(struct work) without flushing workqueue.
> We caught faulty driver by adding a BUG_ON() in INIT_WORK and looking
> at the func pointer in work_struct( which will be pointing to the
> faulty driver work function)
> 
> 1) faulty driver queue_work to system_unbownded_wq
> 2) free work_struct memory, but it is still queued in the work queue.
> 3) another driver request the memory from SLAB, go the same memory, it INIT_WORK
> 4) process work try to execute the work queued by the faulty driver,
> result in a crash.

Ah, good to hear.  I think bugs like the above should be detectable
with CONFIG_DEBUG_OBJECTS_WORK, so if you see something similar next
time, please try it out.

Thanks.

-- 
tejun
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