Re: [PATCH 3/8] cfq-iosched: fix oom cfq_queue ref leak in cfq_set_request()

[Jeff Moyer]

Tejun Heo <tj@xxxxxxxxxx> writes:

> If the cfq_queue cached in cfq_io_cq is the oom one, cfq_set_request()
> replaces it by invoking cfq_get_queue() again without putting the oom
> queue leaking the reference it was holding.  While oom queues are not
> released through reference counting, they're still reference counted
> and this can theoretically lead to the reference count overflowing and
> incorrectly invoke the usual release path on it.
>
> Fix it by making cfq_set_request() put the ref it was holding.
>
> Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
> Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
> Cc: Arianna Avanzini <avanzini.arianna@xxxxxxxxx>

Reviewed-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
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