Re: [GIT PULL] Core block IO bits for 2.6.39 - early Oops

[Chris Mason <chris.mason@oracle.com>]

Excerpts from Markus Trippelsdorf's message of 2011-03-25 10:14:13 -0400:
> On 2011.03.25 at 15:10 +0100, Jens Axboe wrote:
> > On 2011-03-25 14:09, Markus Trippelsdorf wrote:
> > > On 2011.03.25 at 13:44 +0100, Jens Axboe wrote:
> > >> On 2011-03-25 10:57, Markus Trippelsdorf wrote:
> > >>>
> > >>> Reverting it solves all problems here.
> > >>
> > >> Can you try this one?
> > > 
> > > This one doesn't help; I still get the same BUG.
> > > 
> > > BTW if you're having trouble reproducing this, here is the only non
> > > stock xfs option that I use on the affected partitions:
> > > 
> > > noatime,logbsize=262144
> > 
> > This?
> 
> No.
> 

I was able to reproduce it here.  This is working for me:


diff --git a/block/blk-core.c b/block/blk-core.c
index 59b5c00..88f5f6a 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -271,7 +271,7 @@ EXPORT_SYMBOL(blk_start_queue);
  **/
 void blk_stop_queue(struct request_queue *q)
 {
-	cancel_delayed_work(&q->delay_work);
+	__cancel_delayed_work(&q->delay_work);
 	queue_flag_set(QUEUE_FLAG_STOPPED, q);
 }
 EXPORT_SYMBOL(blk_stop_queue);
@@ -1193,6 +1193,7 @@ static bool attempt_plug_merge(struct task_struct *tsk, struct request_queue *q,
 	struct request *rq;
 	bool ret = false;
 
+	preempt_disable();
 	plug = tsk->plug;
 	if (!plug)
 		goto out;
@@ -1215,6 +1216,7 @@ static bool attempt_plug_merge(struct task_struct *tsk, struct request_queue *q,
 		}
 	}
 out:
+	preempt_enable();
 	return ret;
 }
 
@@ -1309,6 +1311,7 @@ get_rq:
 		put_cpu();
 	}
 
+	preempt_disable();
 	plug = current->plug;
 	if (plug) {
 		if (!plug->should_sort && !list_empty(&plug->list)) {
@@ -1324,7 +1327,9 @@ get_rq:
 		req->cmd_flags |= REQ_ON_PLUG;
 		list_add_tail(&req->queuelist, &plug->list);
 		drive_stat_acct(req, 1);
+		preempt_enable();
 	} else {
+		preempt_enable();
 		spin_lock_irq(q->queue_lock);
 		add_acct_request(q, req, where);
 		__blk_run_queue(q, false);