Patch "blk-mq: Fix tagset reinit in the presence of cpu hot-unplug" has been added to the 4.9-stable tree

[<gregkh@linuxfoundation.org>]

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;a=summary

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