4.16-stable review patch. If anyone has any objections, please let me know.
------------------ From: Ming Lei <[email protected]> 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 <[email protected]> Tested-by: Christian Borntraeger <[email protected]> Reviewed-by: Christoph Hellwig <[email protected]> Reviewed-by: Sagi Grimberg <[email protected]> Fixes: 20e4d81393196 ("blk-mq: simplify queue mapping & schedule with each possisble CPU") Cc: [email protected] Signed-off-by: Ming Lei <[email protected]> Signed-off-by: Jens Axboe <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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; } }
