From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0E009C433E0 for ; Mon, 18 May 2020 09:34:15 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id CB5A5207ED for ; Mon, 18 May 2020 09:34:14 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="D4vI4CyS" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CB5A5207ED Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=yandex-team.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:40362 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1jacA2-0002W9-0y for qemu-devel@archiver.kernel.org; Mon, 18 May 2020 05:34:14 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:53198) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jac9I-000227-O9; Mon, 18 May 2020 05:33:28 -0400 Received: from forwardcorp1p.mail.yandex.net ([77.88.29.217]:40888) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1jac9H-0004fw-7a; Mon, 18 May 2020 05:33:28 -0400 Received: from mxbackcorp1g.mail.yandex.net (mxbackcorp1g.mail.yandex.net [IPv6:2a02:6b8:0:1402::301]) by forwardcorp1p.mail.yandex.net (Yandex) with ESMTP id 9495B2E1517; Mon, 18 May 2020 12:33:24 +0300 (MSK) Received: from myt4-18a966dbd9be.qloud-c.yandex.net (myt4-18a966dbd9be.qloud-c.yandex.net [2a02:6b8:c00:12ad:0:640:18a9:66db]) by mxbackcorp1g.mail.yandex.net (mxbackcorp/Yandex) with ESMTP id Unkxzjj1vQ-XLr0kXPG; Mon, 18 May 2020 12:33:24 +0300 Precedence: bulk DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1589794404; bh=px4ZXUb3zc9xNZkVJyG9uWZYuHfYAy8Hl09o5/fez0g=; h=In-Reply-To:Message-ID:Subject:To:From:References:Date:Cc; b=D4vI4CySrFBDM3npC6iIf3bM1pLg83XxMpPYQDVXqKIUPX82q04ESA6Y6FXFUCSAe yeAtxBAf0xDZ4dkodn7PWAuPrNrFYyB7C8NdGklWQIfiPkHZDDFxOpJZ8mvRkRYyza daG5BuRkir4a+50iIlt+GeN7zaalRo4/0I6apjqU= Authentication-Results: mxbackcorp1g.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-vpn.dhcp.yndx.net (dynamic-vpn.dhcp.yndx.net [2a02:6b8:b080:7514::1:b]) by myt4-18a966dbd9be.qloud-c.yandex.net (smtpcorp/Yandex) with ESMTPSA id xQsbtb6aWo-XKWKuCab; Mon, 18 May 2020 12:33:21 +0300 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client certificate not present) Date: Mon, 18 May 2020 12:33:19 +0300 From: Dima Stepanov To: Jason Wang Subject: Re: [PATCH v2 5/5] vhost: add device started check in migration set log Message-ID: <20200518093313.GA6489@dimastep-nix> References: <20200511092541.GA27558@dimastep-nix> <20200512093521.GA5363@dimastep-nix> <20200512235934-mutt-send-email-mst@kernel.org> <20200513094703.GA15906@dimastep-nix> <722839b2-9412-b768-3ce6-d1b697d6d5dd@redhat.com> <20200515165449.GA1627@dimastep-nix> <6bf8a077-01fb-dfd1-164e-440d313503d3@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <6bf8a077-01fb-dfd1-164e-440d313503d3@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) Received-SPF: pass client-ip=77.88.29.217; envelope-from=dimastep@yandex-team.ru; helo=forwardcorp1p.mail.yandex.net X-detected-operating-system: by eggs.gnu.org: First seen = 2020/05/18 05:28:00 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, SPF_PASS=-0.001, URIBL_BLOCKED=0.001 autolearn=_AUTOLEARN X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Fam Zheng , Kevin Wolf , Stefan Hajnoczi , "open list:Block layer core" , "Michael S. Tsirkin" , "open list:All patches CC here" , "Dr. David Alan Gilbert" , Gonglei , Li Feng , yc-core@yandex-team.ru, Paolo Bonzini , =?iso-8859-1?Q?Marc-Andr=E9?= Lureau , Raphael Norwitz , Max Reitz Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Mon, May 18, 2020 at 10:52:08AM +0800, Jason Wang wrote: > > On 2020/5/16 上午11:20, Li Feng wrote: > >Hi, Dima. > >This abort is what I have mentioned in my previous email. > >I have triggered this crash without any fix a week ago. > >And I have written a test patch to let vhost_log_global_start return > >int and propagate the error to up layer. > >However, my change is a little large, because the origin callback > >return void, and don't do some rollback. > >After test, the migration could migrate to dst successfully, and fio > >is still running perfectly, but the src vm is still stuck here, no > >crash. > > > >Is it right to return this error to the up layer? > > > That could be a solution or we may ask David for more suggestion. > > Another thing that might be useful is to block re connection during > migration. I've written a little more information as answer to Feng's mail. But what if add some new callback to get the device started state (started or not). And for the vhost-user (or at least vhost-usr-blk) devices it will use the connected field also to return the device state: - disconnect -> not started For other devices we can just return the started field value as it is right now. No other comments mixed in below. > > Thanks > > > > > >Thanks, > >Feng Li > > > >Dima Stepanov 于2020年5月16日周六 上午12:55写道： > >>On Thu, May 14, 2020 at 03:34:24PM +0800, Jason Wang wrote: > >>>On 2020/5/13 下午5:47, Dima Stepanov wrote: > >>>>>> case CHR_EVENT_CLOSED: > >>>>>> /* a close event may happen during a read/write, but vhost > >>>>>> * code assumes the vhost_dev remains setup, so delay the > >>>>>> * stop & clear to idle. > >>>>>> * FIXME: better handle failure in vhost code, remove bh > >>>>>> */ > >>>>>> if (s->watch) { > >>>>>> AioContext *ctx = qemu_get_current_aio_context(); > >>>>>> > >>>>>> g_source_remove(s->watch); > >>>>>> s->watch = 0; > >>>>>> qemu_chr_fe_set_handlers(&s->chr, NULL, NULL, NULL, NULL, > >>>>>> NULL, NULL, false); > >>>>>> > >>>>>> aio_bh_schedule_oneshot(ctx, chr_closed_bh, opaque); > >>>>>> } > >>>>>> break; > >>>>>> > >>>>>>I think it's time we dropped the FIXME and moved the handling to common > >>>>>>code. Jason? Marc-André? > >>>>>I agree. Just to confirm, do you prefer bh or doing changes like what is > >>>>>done in this series? It looks to me bh can have more easier codes. > >>>>Could it be a good idea just to make disconnect in the char device but > >>>>postphone clean up in the vhost-user-blk (or any other vhost-user > >>>>device) itself? So we are moving the postphone logic and decision from > >>>>the char device to vhost-user device. One of the idea i have is as > >>>>follows: > >>>> - Put ourself in the INITIALIZATION state > >>>> - Start these vhost-user "handshake" commands > >>>> - If we got a disconnect error, perform disconnect, but don't clean up > >>>> device (it will be clean up on the roll back). I can be done by > >>>> checking the state in vhost_user_..._disconnect routine or smth like it > >>> > >>>Any issue you saw just using the aio bh as Michael posted above. > >>> > >>>Then we don't need to deal with the silent vhost_dev_stop() and we will have > >>>codes that is much more easier to understand. > >>I've implemented this solution inside > >>hw/block/vhost-user-blk.c:vhost_user_blk_event() in the similar way by > >>using the s->connected field. Looks good and more correct fix ). I have > >>two questions here before i'll rework the fixes: > >>1. Is it okay to make the similar fix inside vhost_user_blk_event() or > >>we are looking for more generic vhost-user solution? What do you think? > >>2. For migration we require an additional information that for the > >>vhost-user device it isn't an error, because i'm trigerring the > >>following assert error: > >> Core was generated by `x86_64-softmmu/qemu-system-x86_64 -nodefaults -no-user-config -M q35,sata=false'. > >> Program terminated with signal SIGABRT, Aborted. > >> #0 0x00007fb56e729428 in raise () from /lib/x86_64-linux-gnu/libc.so.6 > >> [Current thread is 1 (Thread 0x7fb486ef5700 (LWP 527734))] > >> > >> (gdb) bt > >> #0 0x00007fb56e729428 in raise () from /lib/x86_64-linux-gnu/libc.so.6 > >> #1 0x00007fb56e72b02a in abort () from /lib/x86_64-linux-gnu/libc.so.6 > >> #2 0x00005648ea376ee6 in vhost_log_global_start > >> (listener=0x5648ece4eb08) at ./hw/virtio/vhost.c:857 > >> #3 0x00005648ea2dde7e in memory_global_dirty_log_start () > >> at ./memory.c:2611 > >> #4 0x00005648ea2e68e7 in ram_init_bitmaps (rs=0x7fb4740008c0) > >> at ./migration/ram.c:2305 > >> #5 0x00005648ea2e698b in ram_init_all (rsp=0x5648eb1f0f20 ) > >> at ./migration/ram.c:2323 > >> #6 0x00005648ea2e6cc5 in ram_save_setup (f=0x5648ec609e00, > >> opaque=0x5648eb1f0f20 ) > >> at ./migration/ram.c:2436 > >> #7 0x00005648ea67b7d3 in qemu_savevm_state_setup (f=0x5648ec609e00) at > >> migration/savevm.c:1176 > >> #8 0x00005648ea674511 in migration_thread (opaque=0x5648ec031ff0) at > >> migration/migration.c:3416 > >> #9 0x00005648ea85d65d in qemu_thread_start (args=0x5648ec6057f0) at > >> util/qemu-thread-posix.c:519 > >> #10 0x00007fb56eac56ba in start_thread () from > >> /lib/x86_64-linux-gnu/libpthread.so.0 > >> #11 0x00007fb56e7fb41d in clone () from /lib/x86_64-linux-gnu/libc.so.6 > >> (gdb) frame 2 > >> #2 0x00005648ea376ee6 in vhost_log_global_start > >> (listener=0x5648ece4eb08) at ./hw/virtio/vhost.c:857 > >> 857 abort(); > >> (gdb) list > >> 852 { > >> 853 int r; > >> 854 > >> 855 r = vhost_migration_log(listener, true); > >> 856 if (r < 0) { > >> 857 abort(); > >> 858 } > >> 859 } > >> 860 > >> 861 static void vhost_log_global_stop(MemoryListener *listener) > >>Since bh postphone the clean up, we can't use the ->started field. > >>Do we have any mechanism to get the device type/state in the common > >>vhost_migration_log() routine? So for example for the vhost-user/disconnect > >>device we will be able to return 0. Or should we implement it and introduce > >>it in this patch set? > >> > >>Thanks, Dima. > >> > >>>Thank > >>> > >>> > >>>> - vhost-user command returns error back to the _start() routine > >>>> - Rollback in one place in the start() routine, by calling this > >>>> postphoned clean up for the disconnect > >>>> >