diff options
| author | Ming Lei <ming.lei@redhat.com> | 2018-01-06 16:27:40 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-12 12:32:15 +0200 |
| commit | fb1ef85d58855818f6a1799acabff51a55adff22 (patch) | |
| tree | a2d7eb5f8c7b21a8d1483067e17c1780ca6615a6 /block | |
| parent | eaa077800ff61d494a8ff8700fd3f5fc61abb2fd (diff) | |
blk-mq: fix race between updating nr_hw_queues and switching io sched
[ Upstream commit fb350e0ad99359768e1e80b4784692031ec340e4 ]
In both elevator_switch_mq() and blk_mq_update_nr_hw_queues(), sched tags
can be allocated, and q->nr_hw_queue is used, and race is inevitable, for
example: blk_mq_init_sched() may trigger use-after-free on hctx, which is
freed in blk_mq_realloc_hw_ctxs() when nr_hw_queues is decreased.
This patch fixes the race be holding q->sysfs_lock.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'block')
| -rw-r--r-- | block/blk-mq.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/block/blk-mq.c b/block/blk-mq.c index 12bb7a49c5ba..c28d6b3088a0 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2314,6 +2314,9 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set, struct blk_mq_hw_ctx **hctxs = q->queue_hw_ctx; blk_mq_sysfs_unregister(q); + + /* protect against switching io scheduler */ + mutex_lock(&q->sysfs_lock); for (i = 0; i < set->nr_hw_queues; i++) { int node; @@ -2358,6 +2361,7 @@ static void blk_mq_realloc_hw_ctxs(struct blk_mq_tag_set *set, } } q->nr_hw_queues = i; + mutex_unlock(&q->sysfs_lock); blk_mq_sysfs_register(q); } |