From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41950) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZMamZ-0000Yl-HU for qemu-devel@nongnu.org; Tue, 04 Aug 2015 07:53:24 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZMamV-0002JL-HV for qemu-devel@nongnu.org; Tue, 04 Aug 2015 07:53:23 -0400 References: <55BB2DF7.8010808@kamp.de> <55BB302D.50108@redhat.com> <55BB335A.1010009@kamp.de> <55BB3FE7.3000106@redhat.com> <55C08461.1040308@kamp.de> From: Paolo Bonzini Message-ID: <55C0A7AA.70609@redhat.com> Date: Tue, 4 Aug 2015 13:53:14 +0200 MIME-Version: 1.0 In-Reply-To: <55C08461.1040308@kamp.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [Qemu-stable] Recent patches for 2.4 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Peter Lieven , Stefan Hajnoczi Cc: "qemu-devel@nongnu.org" , qemu-stable@nongnu.org On 04/08/2015 11:22, Peter Lieven wrote: >>>>> edec47c main-loop: fix qemu_notify_event for aio_notify optimization >>>> Part of the above AioContext series. >>> So either the whole series or none of them I guess? >> It's a separate bug, and theoretically it's there in 2.3.1 as well, but >> no one ever reproduced it (it would hang in make check) so not >> worthwhile. > > Can you give me a pointer what the symtoms where? If a thread tries to wake up the main thread using qemu_notify_event(), the main thread will never wake up. This for example could happen if the first thread calls qemu_set_fd_handler() or timer_mod(). > I have a qemu-img convert job on x86_64 that reproducibly hangs on > bdrv_drain_all at the end of the convert process. > I convert from nfs:// to local storage here. I try to figure out which BS > reports busy. Qemu here is still 2.2.1. qemu-img does not use main-loop, so this cannot be the cause. The AioContext bugs only happen when you have a thread executing the main loop and one thread executing aio_poll, so they can also be excluded as the cause of qemu-img problems. Paolo