From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55108) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XEg2o-0005SH-QE for qemu-devel@nongnu.org; Tue, 05 Aug 2014 10:49:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XEg2j-0006T8-G1 for qemu-devel@nongnu.org; Tue, 05 Aug 2014 10:48:54 -0400 Received: from mx.beyond.pl ([92.43.117.49]:54928) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XEg2j-0006Sr-9a for qemu-devel@nongnu.org; Tue, 05 Aug 2014 10:48:49 -0400 Message-ID: <53E0EECA.8020506@beyond.pl> Date: Tue, 05 Aug 2014 16:48:42 +0200 From: =?UTF-8?B?TWFyY2luIEdpYnXFgmE=?= MIME-Version: 1.0 References: <1407167793-20425-1-git-send-email-stefanha@redhat.com> <53E0E9AF.8030103@beyond.pl> In-Reply-To: <53E0E9AF.8030103@beyond.pl> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH] linux-aio: avoid deadlock in nested aio_poll() calls List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Stefan Hajnoczi , qemu-devel@nongnu.org Cc: Kevin Wolf , Paolo Bonzini , Ming Lei On 05.08.2014 16:26, Marcin Gibu=C5=82a 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 resumabl= e. >> Nested event loops can resume completion processing so that request B >> will complete and the deadlock will not occur. >> >> Cc: Kevin Wolf >> Cc: Paolo Bonzini >> Cc: Ming Lei >> Cc: Marcin Gibu=C5=82a >> Reported-by: Marcin Gibu=C5=82a >> Signed-off-by: Stefan Hajnoczi > > Still hangs... I'm sorry, ignore this comment. I've built my test qemu without aio support. Retesting now. --=20 mg