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SubjectRe: [floppy, blk_peek_request] BUG: scheduling while atomic: kworker/u:0/6/0x10000002
On Mon, Nov 05, 2012 at 02:34:13PM +0100, Jiri Kosina wrote:
> On Mon, 5 Nov 2012, Jiri Kosina wrote:
>
> > > I got the below oops in Linux 3.7-rc4 and it's bisected down to
> > >
> > > commit b54e1f88897bcacc2cd359f48ea3b39eaf55f084
> > > Author: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
> > > Date: Mon Aug 27 20:56:51 2012 -0300
> > >
> > > floppy: don't call alloc_ordered_workqueue inside the alloc_disk loop
> >
> > Fengguang,
> >
> > thanks for the report.
> >
> > How reliable is the bisection result? (i.e. how reliably are you able to
> > trigger this oops?).
> >
> > I am having a hard time seeing how that particular commit could be causing
> > this kind of oops.
>
> Hmm, actually I do see an option how this might happen on machines not
> having an actual floppy drive.
>
> Fengguang, does the patch below make any difference for you please?
>
> Thanks.

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.

> out_put_disk:
> for (drive = 0; drive < N_DRIVE; drive++) {
> if (!disks[drive])
> @@ -4340,7 +4341,6 @@ out_put_disk:
> }
> put_disk(disks[drive]);
> }
> - destroy_workqueue(floppy_wq);
> return err;
> }
>
>
> --
> Jiri Kosina
> SUSE Labs
>

--
[]'s
Herton


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