[PATCH] blk-mq: Fix queue usage on failed request allocation

[Max Gurtovoy]

On 8/14/2017 11:40 PM, Keith Busch wrote:
> blk_mq_get_request() does not release the callers queue usage counter
> when allocation fails. The caller still needs to account for its own
> queue usage when it is unable to allocate a request.
>
> Fixes: 1ad43c0078b7 ("blk-mq: don't leak preempt counter/q_usage_counter when allocating rq failed")
>
> Reported-by: Max Gurtovoy <maxg at mellanox.com>
> Signed-off-by: Keith Busch <keith.busch at intel.com>
> ---

tested with 4.13-rc5+ using the following commands in a loop:

1. modprobe nvme
2. sleep 10
3. modprobe -r nvme

Looks good,

Tested-by: Max Gurtovoy <maxg at mellanox.com>