Re: 2.6.20-rc3-mm1 - git-block.patch causes hard lockups

From: Valdis . Kletnieks
Date: Tue Jan 09 2007 - 13:03:56 EST


On Mon, 08 Jan 2007 09:55:24 +0100, Jens Axboe said:
> On Sat, Jan 06 2007, Valdis.Kletnieks@xxxxxx wrote:
> > On Thu, 04 Jan 2007 22:02:00 PST, Andrew Morton said:
> >
> > > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.20-rc
3/2.6.20-rc3-mm1/
> >
> > With git-block.patch applied, my system locks up *hard* at system
> > shutdown time - even alt-sysrq doesn't do anything. Need to do the
> > "power button for 5" stunt to get the system back.
>
> Does this change anything?
>
> diff --git a/block/ll_rw_blk.c b/block/ll_rw_blk.c
> index ec40e44..bae57e0 100644
> --- a/block/ll_rw_blk.c
> +++ b/block/ll_rw_blk.c
> @@ -1542,7 +1542,7 @@ static inline void queue_sync_plugs(request_queue_t *q)
> * If the current process is plugged and has barriers submitted,
> * we will livelock if we don't unplug first.
> */
> - blk_unplug_current();
> + blk_replug_current_nested();
>
> synchronize_qrcu(&q->qrcu);
> }

Nope, still hangs exactly the same way. Maybe I need to get the watchdog
timer stuff working, and see if that can kick the system in a way that
produces a backtrace....

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