blk-mq: avoid setting hctx->tags->cpumask before allocation (1356aae0) · Commits · 戴 / test

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: ("blk-mq: Shared tag enhancements") Signed-off-by:

Akinobu Mita <akinobu.mita@gmail.com> Cc: Keith Busch <keith.busch@intel.com> Cc: Ming Lei <tom.leiming@gmail.com> Reviewed-by:

Christoph Hellwig <hch@lst.de> Signed-off-by:

Jens Axboe <axboe@fb.com>

block/blk-mq.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -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)

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