From: "Marcin Gibuła" <m.gibula@beyond.pl>
To: Stefan Hajnoczi <stefanha@redhat.com>, qemu-devel@nongnu.org
Cc: Kevin Wolf <kwolf@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>,
Ming Lei <ming.lei@canonical.com>
Subject: Re: [Qemu-devel] [PATCH] linux-aio: avoid deadlock in nested aio_poll() calls
Date: Tue, 05 Aug 2014 16:48:42 +0200 [thread overview]
Message-ID: <53E0EECA.8020506@beyond.pl> (raw)
In-Reply-To: <53E0E9AF.8030103@beyond.pl>
On 05.08.2014 16:26, Marcin Gibuła wrote:
> On 04.08.2014 17:56, Stefan Hajnoczi wrote:
>> If two Linux AIO request completions are fetched in the same
>> io_getevents() call, QEMU will deadlock if request A's callback waits
>> for request B to complete using an aio_poll() loop. This was reported
>> to happen with the mirror blockjob.
>>
>> This patch moves completion processing into a BH and makes it resumable.
>> Nested event loops can resume completion processing so that request B
>> will complete and the deadlock will not occur.
>>
>> Cc: Kevin Wolf <kwolf@redhat.com>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Cc: Ming Lei <ming.lei@canonical.com>
>> Cc: Marcin Gibuła <m.gibula@beyond.pl>
>> Reported-by: Marcin Gibuła <m.gibula@beyond.pl>
>> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
>
> Still hangs...
I'm sorry, ignore this comment.
I've built my test qemu without aio support. Retesting now.
--
mg
next prev parent reply other threads:[~2014-08-05 14:49 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-08-04 15:56 [Qemu-devel] [PATCH] linux-aio: avoid deadlock in nested aio_poll() calls Stefan Hajnoczi
2014-08-04 16:10 ` Marcin Gibuła
2014-08-05 10:44 ` Ming Lei
2014-08-05 13:43 ` Stefan Hajnoczi
2014-08-05 14:26 ` Marcin Gibuła
2014-08-05 14:48 ` Marcin Gibuła [this message]
2014-08-05 17:33 ` Marcin Gibuła
2014-08-29 14:59 ` Stefan Hajnoczi
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