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

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From	Jeff Moyer <jmoyer@redhat.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH 3/8] cfq-iosched: fix oom cfq_queue ref leak in cfq_set_request()
Date	Mon, 08 Jun 2015 21:00:02 +0200
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Tejun Heo <tj@kernel.org> 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@kernel.org>
> Cc: Vivek Goyal <vgoyal@redhat.com>
> Cc: Arianna Avanzini <avanzini.arianna@gmail.com>

Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
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Re: [PATCH 3/8] cfq-iosched: fix oom cfq_queue ref leak in cfq_set_request() Jeff Moyer <jmoyer@redhat.com> - 2015-06-08 21:00 +0200

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