Messages in this thread Patch in this message | | | From | Sasha Levin <> | Subject | [PATCH AUTOSEL 5.2 56/76] nvme-multipath: fix possible I/O hang when paths are updated | Date | Thu, 29 Aug 2019 14:12:51 -0400 |
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From: Anton Eidelman <anton@lightbitslabs.com>
[ Upstream commit 504db087aaccdb32af61539916409f7dca31ceb5 ]
nvme_state_set_live() making a path available triggers requeue_work in order to resubmit requests that ended up on requeue_list when no paths were available.
This requeue_work may race with concurrent nvme_ns_head_make_request() that do not observe the live path yet. Such concurrent requests may by made by either: - New IO submission. - Requeue_work triggered by nvme_failover_req() or another ana_work.
A race may cause requeue_work capture the state of requeue_list before more requests get onto the list. These requests will stay on the list forever unless requeue_work is triggered again.
In order to prevent such race, nvme_state_set_live() should synchronize_srcu(&head->srcu) before triggering the requeue_work and prevent nvme_ns_head_make_request referencing an old snapshot of the path list.
Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Anton Eidelman <anton@lightbitslabs.com> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org> --- drivers/nvme/host/multipath.c | 1 + 1 file changed, 1 insertion(+)
diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index e942b3e840687..4f599366bc5ae 100644 --- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -356,6 +356,7 @@ static void nvme_mpath_set_live(struct nvme_ns *ns) srcu_read_unlock(&head->srcu, srcu_idx); } + synchronize_srcu(&ns->head->srcu); kblockd_schedule_work(&ns->head->requeue_work); } -- 2.20.1
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