From 1356aae08338f1c19ce1c67bf8c543a267688fc3 Mon Sep 17 00:00:00 2001
From: Akinobu Mita <akinobu.mita@gmail.com>
Date: Sun, 27 Sep 2015 02:09:19 +0900
Subject: [PATCH] blk-mq: avoid setting hctx->tags->cpumask before allocation
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 <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 | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/block/blk-mq.c b/block/blk-mq.c
index f2d67b4047a04..2fd7283ec62ba 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)
--
2.30.2