Subject: Re: next-20081119: general protection fault: get_next_timer_interrupt()

From: [email-masked]
Date: Mon, 24 Nov 2008 18:08:52 -0800

Stephen Rothwell [[email-masked]] wrote:
> > The block timer code calls del_timer(), should it call del_timer_sync()?
> > It is possible although unlikely that you are hitting del_timer_sync vs
> > del_timer problem in the block timeout code. Can only be seen on SMP
> > systems though!
> 
> Is this still a problem in next-20081121? In that tree, the block commit
> "block: leave the request timeout timer running even on an empty list"
> was changed to add this:
> 
> diff --git a/block/blk-core.c b/block/blk-core.c
> index 04267d6..44f547c 100644
> --- a/block/blk-core.c
> +++ b/block/blk-core.c
> @@ -391,6 +391,7 @@ EXPORT_SYMBOL(blk_stop_queue);
>  void blk_sync_queue(struct request_queue *q)
>  {
>  	del_timer_sync(&q->unplug_timer);
> +	del_timer_sync(&q->timeout);
>  	kblockd_flush_work(&q->unplug_work);
>  }
>  EXPORT_SYMBOL(blk_sync_queue);

I was looking at the Linux tree. Clearly same problem doesn't exist with
the above commit! I wonder why kblockd_flush_work() is called after the
del_timer_sync(). It makes sense to cancel the work and then shutdown
the timer(s). I doubt if you are running into this problem though.

-Malahal.