On Tue, Feb 15, 2011 at 11:45:25AM +0000, Jan Beulich wrote:
> >>> On 15.02.11 at 10:35, Jan Beulich wrote:
> > BUG: scheduling while atomic: swapper/0/0x10010000
>
> Actually, the situation is worse. While the patch sent previously
> allowed that system to boot, it died the moment it tried to
> access its secondary disk (which supports flushes, while the
> primary doesn't):
>
> BUG: scheduling while atomic: swapper/0/0x10010000
> Process swapper (pid: 0, ti=ec004000 task=c04c14e0 task.ti=c04b0000)
> Stack:
> Call Trace:
> Code: cc cc cc cc b8 1c 00 00 00 cd 82 c3 cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc b8 1d 00 00 00 cd 82 <c3> cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc cc
> Kernel panic - not syncing: scheduling while atomic
> Pid: 0, comm: swapper Not tainted 2.6.37-2011-01-22-xen0 #4
> Call Trace:
> [<c010827b>] try_stack_unwind+0x14b/0x170
> [<c010636f>] dump_trace+0x3f/0xf0
> [<c0107e8b>] show_trace_log_lvl+0x4b/0x60
> [<c0107eb8>] show_trace+0x18/0x20
> [<c037104b>] dump_stack+0x6d/0x72
> [<c03710a7>] panic+0x57/0x15b
> [<c0129008>] __schedule_bug+0x58/0x60
> [<c0371786>] schedule+0x466/0x5a0
> [<c037199f>] _cond_resched+0x2f/0x50
> [<c02cb8e5>] do_ide_request+0x55/0x450
> [<c0228698>] __generic_unplug_device+0x28/0x30
> [<c022ab2c>] blk_flush_complete_seq+0xbc/0x1a0 -> queue_next_fseq() -> elv_insert()
Yeah, right. blk_flush_complete_seq_end_io() is on completion path
and shouldn't call directly into request_fn. Can you please test
whether the following patch fixes the problem?
Thanks.
diff --git a/block/blk-core.c b/block/blk-core.c
index 2f4002f..7f59923 100644
--- a/block/blk-core.c
+++ b/block/blk-core.c
@@ -352,7 +352,7 @@ void blk_start_queue(struct request_queue *q)
WARN_ON(!irqs_disabled());
queue_flag_clear(QUEUE_FLAG_STOPPED, q);
- __blk_run_queue(q);
+ __blk_run_queue(q, false);
}
EXPORT_SYMBOL(blk_start_queue);
@@ -403,13 +403,14 @@ EXPORT_SYMBOL(blk_sync_queue);
/**
* __blk_run_queue - run a single device queue
* @q: The queue to run
+ * @force_kblockd: Don't run @q->request_fn directly. Use kblockd.
*
* Description:
* See @blk_run_queue. This variant must be called with the queue lock
* held and interrupts disabled.
*
*/
-void __blk_run_queue(struct request_queue *q)
+void __blk_run_queue(struct request_queue *q, bool force_kblockd)
{
blk_remove_plug(q);
@@ -423,7 +424,7 @@ void __blk_run_queue(struct request_queue *q)
* Only recurse once to avoid overrunning the stack, let the unplug
* handling reinvoke the handler shortly if we already got there.
*/
- if (!queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
+ if (!force_kblockd && !queue_flag_test_and_set(QUEUE_FLAG_REENTER, q)) {
q->request_fn(q);
queue_flag_clear(QUEUE_FLAG_REENTER, q);
} else {
@@ -446,7 +447,7 @@ void blk_run_queue(struct request_queue *q)
unsigned long flags;
spin_lock_irqsave(q->queue_lock, flags);
- __blk_run_queue(q);
+ __blk_run_queue(q, false);
spin_unlock_irqrestore(q->queue_lock, flags);
}
EXPORT_SYMBOL(blk_run_queue);
@@ -1053,7 +1054,7 @@ void blk_insert_request(struct request_queue *q, struct request *rq,
drive_stat_acct(rq, 1);
__elv_add_request(q, rq, where, 0);
- __blk_run_queue(q);
+ __blk_run_queue(q, false);
spin_unlock_irqrestore(q->queue_lock, flags);
}
EXPORT_SYMBOL(blk_insert_request);
diff --git a/block/blk-flush.c b/block/blk-flush.c
index 54b123d..e0bfce8 100644
--- a/block/blk-flush.c
+++ b/block/blk-flush.c
@@ -66,10 +66,12 @@ static void blk_flush_complete_seq_end_io(struct request_queue *q,
/*
* Moving a request silently to empty queue_head may stall the
- * queue. Kick the queue in those cases.
+ * queue. Kick the queue in those cases. This function is called
+ * from request completion path and calling directly into
+ * request_fn may confuse the driver. Always use kblockd.
*/
if (was_empty && next_rq)
- __blk_run_queue(q);
+ __blk_run_queue(q, true);
}
static void pre_flush_end_io(struct request *rq, int error)
diff --git a/block/cfq-iosched.c b/block/cfq-iosched.c
index 7be4c79..ea83a4f 100644
--- a/block/cfq-iosched.c
+++ b/block/cfq-iosched.c
@@ -3355,7 +3355,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
cfqd->busy_queues > 1) {
cfq_del_timer(cfqd, cfqq);
cfq_clear_cfqq_wait_request(cfqq);
- __blk_run_queue(cfqd->queue);
+ __blk_run_queue(cfqd->queue, false);
} else {
cfq_blkiocg_update_idle_time_stats(
&cfqq->cfqg->blkg);
@@ -3370,7 +3370,7 @@ cfq_rq_enqueued(struct cfq_data *cfqd, struct cfq_queue *cfqq,
* this new queue is RT and the current one is BE
*/
cfq_preempt_queue(cfqd, cfqq);
- __blk_run_queue(cfqd->queue);
+ __blk_run_queue(cfqd->queue, false);
}
}
@@ -3731,7 +3731,7 @@ static void cfq_kick_queue(struct work_struct *work)
struct request_queue *q = cfqd->queue;
spin_lock_irq(q->queue_lock);
- __blk_run_queue(cfqd->queue);
+ __blk_run_queue(cfqd->queue, false);
spin_unlock_irq(q->queue_lock);
}
diff --git a/block/elevator.c b/block/elevator.c
index 2569512..236e93c 100644
--- a/block/elevator.c
+++ b/block/elevator.c
@@ -602,7 +602,7 @@ void elv_quiesce_start(struct request_queue *q)
*/
elv_drain_elevator(q);
while (q->rq.elvpriv) {
- __blk_run_queue(q);
+ __blk_run_queue(q, false);
spin_unlock_irq(q->queue_lock);
msleep(10);
spin_lock_irq(q->queue_lock);
@@ -651,7 +651,7 @@ void elv_insert(struct request_queue *q, struct request *rq, int where)
* with anything. There's no point in delaying queue
* processing.
*/
- __blk_run_queue(q);
+ __blk_run_queue(q, false);
break;
case ELEVATOR_INSERT_SORT:
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 9045c52..fb2bb35 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -443,7 +443,7 @@ static void scsi_run_queue(struct request_queue *q)
&sdev->request_queue->queue_flags);
if (flagset)
queue_flag_set(QUEUE_FLAG_REENTER, sdev->request_queue);
- __blk_run_queue(sdev->request_queue);
+ __blk_run_queue(sdev->request_queue, false);
if (flagset)
queue_flag_clear(QUEUE_FLAG_REENTER, sdev->request_queue);
spin_unlock(sdev->request_queue->queue_lock);
diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
index 998c01b..5c3ccfc 100644
--- a/drivers/scsi/scsi_transport_fc.c
+++ b/drivers/scsi/scsi_transport_fc.c
@@ -3829,7 +3829,7 @@ fc_bsg_goose_queue(struct fc_rport *rport)
!test_bit(QUEUE_FLAG_REENTER, &rport->rqst_q->queue_flags);
if (flagset)
queue_flag_set(QUEUE_FLAG_REENTER, rport->rqst_q);
- __blk_run_queue(rport->rqst_q);
+ __blk_run_queue(rport->rqst_q, false);
if (flagset)
queue_flag_clear(QUEUE_FLAG_REENTER, rport->rqst_q);
spin_unlock_irqrestore(rport->rqst_q->queue_lock, flags);
diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index 4d18ff3..d5e444d 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -699,7 +699,7 @@ extern void blk_start_queue(struct request_queue *q);
extern void blk_stop_queue(struct request_queue *q);
extern void blk_sync_queue(struct request_queue *q);
extern void __blk_stop_queue(struct request_queue *q);
-extern void __blk_run_queue(struct request_queue *);
+extern void __blk_run_queue(struct request_queue *q, bool force_kblockd);
extern void blk_run_queue(struct request_queue *);
extern int blk_rq_map_user(struct request_queue *, struct request *,
struct rq_map_data *, void __user *, unsigned long,
--
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