| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.16 42/68] blk-mq: make sure that correct hctx->next_cpu is set | Date | Tue, 17 Apr 2018 17:57:55 +0200 |
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4.16-stable review patch. If anyone has any objections, please let me know.
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From: Ming Lei <ming.lei@redhat.com>
commit a1c735fb790745f94a359df45c11df4a69760389 upstream.
>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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- block/blk-mq.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2439,6 +2439,8 @@ static void blk_mq_map_swqueue(struct re */ hctx->next_cpu = cpumask_first_and(hctx->cpumask, cpu_online_mask); + if (hctx->next_cpu >= nr_cpu_ids) + hctx->next_cpu = cpumask_first(hctx->cpumask); hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH; } }
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