From mboxrd@z Thu Jan 1 00:00:00 1970 From: hch@lst.de (Christoph Hellwig) Date: Sun, 27 Sep 2015 21:01:49 +0200 Subject: [PATCH 01/10] blk-mq: avoid setting hctx->tags->cpumask before allocation In-Reply-To: <1443380518-6829-1-git-send-email-hch@lst.de> References: <1443380518-6829-1-git-send-email-hch@lst.de> Message-ID: <1443380518-6829-2-git-send-email-hch@lst.de> From: Akinobu Mita When unmapped hw queue is remapped after CPU topology is changed, hctx->tags->cpumask has to be set after hctx->tags is setup in blk_mq_map_swqueue(), otherwise it causes null pointer dereference. Fixes: f26cdc8536 ("blk-mq: Shared tag enhancements") Signed-off-by: Akinobu Mita Reviewed-by: Christoph Hellwig Cc: Keith Busch Cc: Jens Axboe Cc: Ming Lei --- block/blk-mq.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index f2d67b4..2fd7283 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1811,7 +1811,6 @@ static void blk_mq_map_swqueue(struct request_queue *q) hctx = q->mq_ops->map_queue(q, i); cpumask_set_cpu(i, hctx->cpumask); - cpumask_set_cpu(i, hctx->tags->cpumask); ctx->index_hw = hctx->nr_ctx; hctx->ctxs[hctx->nr_ctx++] = ctx; } @@ -1851,6 +1850,14 @@ static void blk_mq_map_swqueue(struct request_queue *q) hctx->next_cpu = cpumask_first(hctx->cpumask); hctx->next_cpu_batch = BLK_MQ_CPU_WORK_BATCH; } + + queue_for_each_ctx(q, ctx, i) { + if (!cpu_online(i)) + continue; + + hctx = q->mq_ops->map_queue(q, i); + cpumask_set_cpu(i, hctx->tags->cpumask); + } } static void blk_mq_update_tag_set_depth(struct blk_mq_tag_set *set) -- 1.9.1