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 <[email protected]>
Cc: Keith Busch <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Ming Lei <[email protected]>
---
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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
