linux-kernel - Re: [floppy, blk_peek_request] BUG: scheduling while atomic: kworker/u:0/6/0x10000002

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Message-ID: <alpine.LNX.2.00.1211051753150.24253@pobox.suse.cz>
Date:	Mon, 5 Nov 2012 17:53:42 +0100 (CET)
From:	Jiri Kosina <jkosina@...e.cz>
To:	Vivek Goyal <vgoyal@...hat.com>
Cc:	Herton Ronaldo Krzesinski <herton.krzesinski@...onical.com>,
	Fengguang Wu <fengguang.wu@...el.com>,
	Ben Hutchings <ben@...adent.org.uk>,
	Jens Axboe <axboe@...nel.dk>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [floppy, blk_peek_request] BUG: scheduling while atomic:
 kworker/u:0/6/0x10000002

On Mon, 5 Nov 2012, Vivek Goyal wrote:

> > > Yes, I saw the same thing here, destroy_workqueue should be done before
> > > clearing the queue (blk_cleanup_queue) indeed. user_reset_fdc called
> > > process_fd_request and that scheduled redo_fd_request, that tries to
> > > take the queue already cleaned up in set_next_request I expect.
> > > 
> > > > 
> > > > 
> > > > 
> > > > 
> > > >  drivers/block/floppy.c |    2 +-
> > > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > > 
> > > > diff --git a/drivers/block/floppy.c b/drivers/block/floppy.c
> > > > index 1c49d71..3b9cc0f 100644
> > > > --- a/drivers/block/floppy.c
> > > > +++ b/drivers/block/floppy.c
> > > > @@ -4329,6 +4329,7 @@ out_unreg_region:
> > > >  	platform_driver_unregister(&floppy_driver);
> > > >  out_unreg_blkdev:
> > > >  	unregister_blkdev(FLOPPY_MAJOR, "fd");
> > > > +	destroy_workqueue(floppy_wq);
> > > 
> > > This should go right after the out_put_disk label, otherwise we may
> > > leak the floppy_wq on early error.
> > 
> > Indeed.
> > 
> > Fengguang, could you please test with the patch below instead? (it should 
> > be functionally equivalent in most of the cases though).
> > 
> 
> What about floppy_module_exit(). There also we seem to cleanup the queue
> first before flushing and destroying floppy_wq workqueue.

Yup, will fix that up in a final patch once we have confirmation from 
Fengguang that it fixes the problem he is seeing.

Thanks,

-- 
Jiri Kosina
SUSE Labs
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