[Bionic,v2,11/21] blk-mq: make sure that correct hctx->next_cpu is set

Message ID 20180510162334.2058-12-joserz@linux.vnet.ibm.com
State New
Headers show
  • blk-mq scheduler fixes
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Commit Message

Jose Ricardo Ziviani May 10, 2018, 4:23 p.m.
From: Ming Lei <ming.lei@redhat.com>

From commit 20e4d81393196 (blk-mq: simplify queue mapping & schedule
with each possisble CPU), one hctx can be mapped from all offline CPUs,
then hctx->next_cpu can be set as wrong.

This patch fixes this issue by making hctx->next_cpu pointing to the
first CPU in hctx->cpumask if all CPUs in hctx->cpumask are offline.

Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Fixes: 20e4d81393196 ("blk-mq: simplify queue mapping & schedule with each possisble CPU")
Cc: stable@vger.kernel.org
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit a1c735fb790745f94a359df45c11df4a69760389)
Signed-off-by: Jose Ricardo Ziviani <joserz@linux.ibm.com>
 block/blk-mq.c | 2 ++
 1 file changed, 2 insertions(+)


diff --git a/block/blk-mq.c b/block/blk-mq.c
index f5e7624d6fe1..ce5a08e3c0f3 100644
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -2280,6 +2280,8 @@  static void blk_mq_map_swqueue(struct request_queue *q)
 		hctx->next_cpu = cpumask_first_and(hctx->cpumask,
+		if (hctx->next_cpu >= nr_cpu_ids)
+			hctx->next_cpu = cpumask_first(hctx->cpumask);
 		hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH;