This is a note to let you know that I've just added the patch titled

blk-mq: Fix tagset reinit in the presence of cpu hot-unplug

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: blk-mq-fix-tagset-reinit-in-the-presence-of-cpu-hot-unplug.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Mon Dec 18 14:12:34 CET 2017

From: Sagi Grimberg sagi@grimberg.me Date: Mon, 13 Mar 2017 16:10:11 +0200 Subject: blk-mq: Fix tagset reinit in the presence of cpu hot-unplug

From: Sagi Grimberg sagi@grimberg.me

[ Upstream commit 0067d4b020ea07a58540acb2c5fcd3364bf326e0 ]

In case cpu was unplugged, we need to make sure not to assume that the tags for that cpu are still allocated. so check for null tags when reinitializing a tagset.

Reported-by: Yi Zhang yizhan@redhat.com Signed-off-by: Sagi Grimberg sagi@grimberg.me Signed-off-by: Jens Axboe axboe@fb.com Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- block/blk-mq-tag.c | 3 +++ 1 file changed, 3 insertions(+)

--- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -311,6 +311,9 @@ int blk_mq_reinit_tagset(struct blk_mq_t for (i = 0; i < set->nr_hw_queues; i++) { struct blk_mq_tags *tags = set->tags[i];

+ if (!tags) + continue; + for (j = 0; j < tags->nr_tags; j++) { if (!tags->rqs[j]) continue;

Patches currently in stable-queue which might be from sagi@grimberg.me are

queue-4.9/blk-mq-fix-tagset-reinit-in-the-presence-of-cpu-hot-unplug.patch queue-4.9/nvmet-confirm-sq-percpu-has-scheduled-and-switched-to-atomic.patch queue-4.9/nvme-use-kref_get_unless_zero-in-nvme_find_get_ns.patch queue-4.9/nvme-loop-fix-a-possible-use-after-free-when-destroying-the-admin-queue.patch queue-4.9/nvmet-rdma-fix-a-possible-uninitialized-variable-dereference.patch