On 4/24/20 12:23 PM, Ming Lei wrote:
Run queue on dead CPU still may be triggered in some corner case,
such as one request is requeued after CPU hotplug is handled.
So handle this corner case during run queue.
Cc: John Garry <john.garry@xxxxxxxxxx>
Cc: Bart Van Assche <bvanassche@xxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
block/blk-mq.c | 30 ++++++++++--------------------
1 file changed, 10 insertions(+), 20 deletions(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index a4a26bb23533..68088ff5460c 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -43,6 +43,8 @@
static void blk_mq_poll_stats_start(struct request_queue *q);
static void blk_mq_poll_stats_fn(struct blk_stat_callback *cb);
+static void blk_mq_hctx_deactivate(struct blk_mq_hw_ctx *hctx);
+
static int blk_mq_poll_stats_bkt(const struct request *rq)
{
int ddir, sectors, bucket;
@@ -1376,28 +1378,16 @@ static void __blk_mq_run_hw_queue(struct blk_mq_hw_ctx *hctx)
int srcu_idx;
/*
- * We should be running this queue from one of the CPUs that
- * are mapped to it.
- *
- * There are at least two related races now between setting
- * hctx->next_cpu from blk_mq_hctx_next_cpu() and running
- * __blk_mq_run_hw_queue():
- *
- * - hctx->next_cpu is found offline in blk_mq_hctx_next_cpu(),
- * but later it becomes online, then this warning is harmless
- * at all
- *
- * - hctx->next_cpu is found online in blk_mq_hctx_next_cpu(),
- * but later it becomes offline, then the warning can't be
- * triggered, and we depend on blk-mq timeout handler to
- * handle dispatched requests to this hctx
+ * BLK_MQ_S_INACTIVE may not deal with some requeue corner case:
+ * one request is requeued after cpu unplug is handled, so check
+ * if the hctx is actually inactive. If yes, deactive it and
+ * re-submit all requests in the queue.
*/
if (!cpumask_test_cpu(raw_smp_processor_id(), hctx->cpumask) &&
- cpu_online(hctx->next_cpu)) {
- printk(KERN_WARNING "run queue from wrong CPU %d, hctx %s\n",
- raw_smp_processor_id(),
- cpumask_empty(hctx->cpumask) ? "inactive": "active");
- dump_stack();
+ cpumask_next_and(-1, hctx->cpumask, cpu_online_mask) >=
+ nr_cpu_ids) {
+ blk_mq_hctx_deactivate(hctx);
+ return;
}
/*
Reviewed-by: Hannes Reinecke <hare@xxxxxxx>
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
hare@xxxxxxx +49 911 74053 688
SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
