Re: [PATCH] block: fix intermittent dm timeout based oops

[James Bottomley]

On Fri, 2009-04-03 at 16:32 +0200, Christof Schmitt wrote:
> On Tue, Mar 24, 2009 at 08:17:30AM +0100, Hannes Reinecke wrote:
> > Very rarely under stress testing of dm, oopses are occuring as
> > something tampers with an old stack frame.  This has been traced back
> > to blk_abort_queue() leaving a timeout_list pointing to the stack.
> > The reason is that sometimes blk_abort_request() won't delete the
> > timer (if the request is marked as complete but before the timer has
> > been removed, a small race window).  Fix this by splicing back from
> > the ususally empty list to the q->timeout_list.
> > 
> > Signed-off-by: Hannes Reinecke <hare@xxxxxxx>
> > ---
> >  block/blk-timeout.c |    6 ++++++
> >  1 files changed, 6 insertions(+), 0 deletions(-)
> > 
> > diff --git a/block/blk-timeout.c b/block/blk-timeout.c
> > index bbbdc4b..6213123 100644
> > --- a/block/blk-timeout.c
> > +++ b/block/blk-timeout.c
> > @@ -224,6 +224,12 @@ void blk_abort_queue(struct request_queue *q)
> >  	list_for_each_entry_safe(rq, tmp, &list, timeout_list)
> >  		blk_abort_request(rq);
> > 
> > +	/*
> > +	 * Occasionally, blk_abort_request() will return without
> > +	 * deleting the element from the list
> > +	 */
> > +	list_splice(&list, &q->timeout_list);
> > +
> >  	spin_unlock_irqrestore(q->queue_lock, flags);
> > 
> >  }
> > -- 
> > 1.5.3.2
> 
> I just noticed that this fix is not upstream yet and i have seen test
> cases hitting this problem.
> 
> Jens, are you going to included this patch, or should this go through
> the SCSI tree?

It's a block patch, so it goes through the block tree ... it also needs
backporting to stable.

James


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