From: Jens Axboe <axboe@kernel.dk>
To: Jeff Moyer <jmoyer@redhat.com>, Ming Lei <tom.leiming@gmail.com>
Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] block: fix mq request allocation
Date: Mon, 02 Dec 2013 09:49:14 -0700 [thread overview]
Message-ID: <529CBA0A.8020703@kernel.dk> (raw)
In-Reply-To: <x49ob4z700n.fsf@segfault.boston.devel.redhat.com>
On 12/02/2013 08:20 AM, Jeff Moyer wrote:
> Ming Lei <tom.leiming@gmail.com> writes:
>
>> blk_mq_alloc_request_pinned() may return NULL request in case of
>> !__GFP_WAIT, so cause its callers to derefence NULL pointer for
>> releasing current context.
>>
>> This patch introduces two flags to address the issue.
>
> Hi, Ming,
>
>
> Good catch, but your patch seems overly complicated. How about
> something like the following (compile-tested only), instead? Note that
> I did not touch blk_make_request, as the put_ctx there seems to
> correlate to a get_ctx earlier in the function (not a leaked reference
> from __blk_mq_alloc_request).
I would tend to agree, it's overly complicated. The bug is real, however.
> p.s. Jens, every time I see GFP_ATOMIC|__GFP_WAIT, my head explodes. Just sayin'.
It's perfectly fine :-)
--
Jens Axboe
next prev parent reply other threads:[~2013-12-02 16:50 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-01 9:27 [PATCH] block: fix mq request allocation Ming Lei
2013-12-02 15:20 ` Jeff Moyer
2013-12-02 16:49 ` Jens Axboe [this message]
2013-12-02 19:14 ` Jeff Moyer
2013-12-03 1:33 ` Ming Lei
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