From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:55090) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1adx4z-0005K6-TP for qemu-devel@nongnu.org; Thu, 10 Mar 2016 04:40:29 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1adx4v-00035I-So for qemu-devel@nongnu.org; Thu, 10 Mar 2016 04:40:25 -0500 Received: from e06smtp06.uk.ibm.com ([195.75.94.102]:58337) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1adx4v-00035B-JJ for qemu-devel@nongnu.org; Thu, 10 Mar 2016 04:40:21 -0500 Received: from localhost by e06smtp06.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 10 Mar 2016 09:40:20 -0000 Received: from b06cxnps3075.portsmouth.uk.ibm.com (d06relay10.portsmouth.uk.ibm.com [9.149.109.195]) by d06dlp01.portsmouth.uk.ibm.com (Postfix) with ESMTP id 40CEC17D805A for ; Thu, 10 Mar 2016 09:40:47 +0000 (GMT) Received: from d06av06.portsmouth.uk.ibm.com (d06av06.portsmouth.uk.ibm.com [9.149.37.217]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u2A9eIYA62587060 for ; Thu, 10 Mar 2016 09:40:18 GMT Received: from d06av06.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av06.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u2A9eIfu016313 for ; Thu, 10 Mar 2016 04:40:18 -0500 References: <1455470231-5223-1-git-send-email-pbonzini@redhat.com> <1455470231-5223-6-git-send-email-pbonzini@redhat.com> <56E01544.6060305@de.ibm.com> <56E01D3F.1060204@redhat.com> <56E03333.5020601@de.ibm.com> <56E04C9B.7070801@redhat.com> <20160310015154.GD23632@ad.usersys.redhat.com> <56E13849.3060409@de.ibm.com> From: Christian Borntraeger Message-ID: <56E14101.4030405@de.ibm.com> Date: Thu, 10 Mar 2016 10:40:17 +0100 MIME-Version: 1.0 In-Reply-To: <56E13849.3060409@de.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 5/8] virtio-blk: fix "disabled data plane" mode List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Fam Zheng , Paolo Bonzini Cc: Bo Tu , qemu-devel@nongnu.org On 03/10/2016 10:03 AM, Christian Borntraeger wrote: > On 03/10/2016 02:51 AM, Fam Zheng wrote: > [...] >> The aio_poll() inside "blk_set_aio_context(s->conf->conf.blk, s->ctx)" looks >> suspicious: >> >> main thread iothread >> ---------------------------------------------------------------------------- >> virtio_blk_handle_output() >> virtio_blk_data_plane_start() >> vblk->dataplane_started = true; >> blk_set_aio_context() >> bdrv_set_aio_context() >> bdrv_drain() >> aio_poll() >> >> virtio_blk_handle_output() >> /* s->dataplane_started is true */ >> !!! -> virtio_blk_handle_request() >> event_notifier_set(ioeventfd) >> aio_poll() >> virtio_blk_handle_request() >> >> Christian, could you try the followed patch? The aio_poll above is replaced >> with a "limited aio_poll" that doesn't disptach ioeventfd. >> >> (Note: perhaps moving "vblk->dataplane_started = true;" after >> blk_set_aio_context() also *works around* this.) >> >> --- >> >> diff --git a/block.c b/block.c >> index ba24b8e..e37e8f7 100644 >> --- a/block.c >> +++ b/block.c >> @@ -4093,7 +4093,9 @@ void bdrv_attach_aio_context(BlockDriverState *bs, >> >> void bdrv_set_aio_context(BlockDriverState *bs, AioContext *new_context) >> { >> - bdrv_drain(bs); /* ensure there are no in-flight requests */ >> + /* ensure there are no in-flight requests */ >> + bdrv_drained_begin(bs); >> + bdrv_drained_end(bs); >> >> bdrv_detach_aio_context(bs); >> > > That seems to do the trick. Or not. Crashed again :-( here is a trace with debugging enabled. The opaque value is zero, which is not good. #0 0x0000000010329f98 in bdrv_co_do_rw (opaque=0x0) at block/io.c:2170 #1 0x00000000103b33a2 in coroutine_trampoline (i0=1023, i1=1946159824) at qemu/util/coroutine-ucontext.c:79 #2 0x000003ff7d9d150a in __makecontext_ret () from /lib64/libc.so.6 Still no idea why.