Re: ? PANICKED: Test report for kernel 5.13.0-rc3 (block, 30ec225a)

[Bruno Goncalves <bgoncalv@redhat.com>]

On Tue, Jun 15, 2021 at 6:01 PM Christoph Hellwig <hch@lst.de> wrote:
>
> On Tue, Jun 15, 2021 at 09:58:03PM +0800, Ming Lei wrote:
> > On Tue, Jun 15, 2021 at 7:52 PM Christoph Hellwig <hch@lst.de> wrote:
> > >
> > > On Mon, Jun 14, 2021 at 02:40:58PM +0200, Bruno Goncalves wrote:
> > > > Hi,
> > > >
> > > > We've noticed a kernel oops during the stress-ng test on aarch64 more log
> > > > details on [1]. Christoph, do you think this could be related to the recent
> > > > blk_cleanup_disk changes [2]?
> > >
> > > It doesn't really look very related.  Any chance you could bisect it?
> >
> > It should be the wrong order between freeing tagset and cleanup disk:
> >
> > static void loop_remove(struct loop_device *lo)
> > {
> >         ...
> >         blk_mq_free_tag_set(&lo->tag_set);
> >         blk_cleanup_disk(lo->lo_disk);
> >         ...
> >  }
>
> Indeed.  Something like this should fix the issue:
>
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index 9a48b3f9a15c..e0c4de392eab 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -2172,8 +2172,8 @@ static int loop_add(struct loop_device **l, int i)
>  static void loop_remove(struct loop_device *lo)
>  {
>         del_gendisk(lo->lo_disk);
> -       blk_mq_free_tag_set(&lo->tag_set);
>         blk_cleanup_disk(lo->lo_disk);
> +       blk_mq_free_tag_set(&lo->tag_set);
>         mutex_destroy(&lo->lo_mutex);
>         kfree(lo);
>  }
>
Thank you Christoph and Ming,

I've tested the patch and the panic is gone. I still hit some kernel
oops, but that doesn't seem related to any block change.

Bruno