This is a note to let you know that I've just added the patch titled
[PATCH-stable] nvme: Fix memory order on async queue deletion
to the 4.4-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:
nvme-fix-memory-order-on-async-queue-deletion.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From keith.busch@xxxxxxxxx Tue Nov 21 17:57:03 2017
From: Keith Busch <keith.busch@xxxxxxxxx>
Date: Thu, 16 Nov 2017 16:57:10 -0700
Subject: [PATCH-stable] nvme: Fix memory order on async queue deletion
To: linux-nvme@xxxxxxxxxxxxxxxxxxx, stable@xxxxxxxxxxxxxxx
Cc: Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx>, Keith Busch <keith.busch@xxxxxxxxx>
Message-ID: <20171116235710.20224-1-keith.busch@xxxxxxxxx>
From: Keith Busch <keith.busch@xxxxxxxxx>
This patch is a fix specific to the 3.19 - 4.4 kernels. The 4.5 kernel
inadvertently fixed this bug differently (db3cbfff5bcc0), but is not
a stable candidate due it being a complicated re-write of the entire
feature.
This patch fixes a potential timing bug with nvme's asynchronous queue
deletion, which causes an allocated request to be accidentally released
due to the ordering of the shared completion context among the sq/cq
pair. The completion context saves the request that issued the queue
deletion. If the submission side deletion happens to reset the active
request, the completion side will release the wrong request tag back into
the pool of available tags. This means the driver will create multiple
commands with the same tag, corrupting the queue context.
The error is observable in the kernel logs like:
"nvme XX:YY:ZZ completed id XX twice on qid:0"
In this particular case, this message occurs because the queue is
corrupted.
The following timing sequence demonstrates the error:
CPU A CPU B
----------------------- -----------------------------
nvme_irq
nvme_process_cq
async_completion
queue_kthread_work -----------> nvme_del_sq_work_handler
nvme_delete_cq
adapter_async_del_queue
nvme_submit_admin_async_cmd
cmdinfo->req = req;
blk_mq_free_request(cmdinfo->req); <-- wrong request!!!
This patch fixes the bug by releasing the request in the completion side
prior to waking the submission thread, such that that thread can't muck
with the shared completion context.
Fixes: a4aea5623d4a5 ("NVMe: Convert to blk-mq")
Signed-off-by: Keith Busch <keith.busch@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/nvme/host/pci.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -350,8 +350,8 @@ static void async_completion(struct nvme
struct async_cmd_info *cmdinfo = ctx;
cmdinfo->result = le32_to_cpup(&cqe->result);
cmdinfo->status = le16_to_cpup(&cqe->status) >> 1;
- queue_kthread_work(cmdinfo->worker, &cmdinfo->work);
blk_mq_free_request(cmdinfo->req);
+ queue_kthread_work(cmdinfo->worker, &cmdinfo->work);
}
static inline struct nvme_cmd_info *get_cmd_from_tag(struct nvme_queue *nvmeq,
Patches currently in stable-queue which might be from keith.busch@xxxxxxxxx are
queue-4.4/nvme-fix-memory-order-on-async-queue-deletion.patch