Messages in this thread Patch in this message | | | From | Akinobu Mita <> | Subject | [PATCH v3 1/7] blk-mq: avoid access hctx->tags->cpumask before allocation | Date | Sun, 19 Jul 2015 01:28:17 +0900 |
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When unmapped hw queue is remapped after CPU topology is changed, hctx->tags->cpumask is set before hctx->tags is allocated in blk_mq_map_swqueue().
In order to fix this null pointer dereference, hctx->tags must be allocated before configuring hctx->tags->cpumask.
Fixes: f26cdc8536 ("blk-mq: Shared tag enhancements") Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Keith Busch <keith.busch@intel.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Ming Lei <tom.leiming@gmail.com> --- 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 7d842db..f29f766 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1821,7 +1821,6 @@ 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; } @@ -1861,6 +1860,14 @@ 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
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