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[184.147.14.204]) by smtp.gmail.com with ESMTPSA id o4sm2040873qkk.75.2020.10.07.11.33.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 07 Oct 2020 11:33:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1602095613; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=iuBPqxcsv0aTQ0rcLgkKxT6k78kO6ea209eSJdeHNsw=; b=QpJztbHiiNM1xFmI41ObH33j+AZgBf/B2BwF3tlNcGwLwIPlC97uGjg9BS6QvL0eCNRVqY 3/RrnOq/3jqfAWR2QtwYIwzHSxKL5X2WbLO3LGOIvVwDgb1y/gcKPUhylaIeod0C8pAuku vCp7gIuSud0gPtknhmtxD8qmOlI2s+Y= X-MC-Unique: Ha_E2Zg4P-uJwMCfTL3pHA-1 X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=iuBPqxcsv0aTQ0rcLgkKxT6k78kO6ea209eSJdeHNsw=; b=pwnvt+KYgkCQNYEfb0+662yk33535rwNU8aJ+pXBLTXMx23NNTFaLNTJ+m5Hz7tUKZ 8LHvnZFHC7lz3OqVxP2rNEBWL+sKm0m0LhtRa4qLiaDvU1ahUgsFWIFewjI3tL50kJhO FS2HeIJVNHUyirlGlB5lSyKEw+gCKi6qlh0iS0SKxYSsqId0oH6Iccmr+oU/Jst+ADol IMkr+ECZJS9kBKz+uAWV3hC7/7prhiKeqXDkm9VScUYvppY2P/H2qCb075zr8T/kDuRD wXPRwuwFOaiwDTSBqkIDQbJ3xHxyfrFx0i71xWUTtLCUcJXvCUqQegr5cNpNmEgWosWl VjHA== X-Gm-Message-State: AOAM530LkN8CPoCNI1N99d9x2qQJwSdIJhukUOYyQfEOR9dmSTu+LcPg MkWBnB/nokOPYFQFPwnoVyqi8+ArMBvGcwWExW007H2ZKNsOBGUkr+tRsdqit/SA4XmCHxPuTQJ vm1/M+fPz78Nd1fA= X-Received: by 2002:ac8:6047:: with SMTP id k7mr4720601qtm.60.1602095608408; Wed, 07 Oct 2020 11:33:28 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzLQd3LS9nzREe4DOgey+hzA8BMSKQKHWH0D51vX5vjt5qFY4u6ji4LJOMrEQiD4caJiPqRCA== X-Received: by 2002:ac8:6047:: with SMTP id k7mr4720561qtm.60.1602095607863; Wed, 07 Oct 2020 11:33:27 -0700 (PDT) From: Peter Xu To: qemu-devel@nongnu.org Subject: [PATCH] migration/postcopy: Release fd before going into 'postcopy-pause' Date: Wed, 7 Oct 2020 14:33:24 -0400 Message-Id: <20201007183324.288379-1-peterx@redhat.com> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=peterx@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=216.205.24.124; envelope-from=peterx@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-detected-operating-system: by eggs.gnu.org: First seen = 2020/10/07 00:54:30 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, DKIMWL_WL_HIGH=-0.742, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Dr . David Alan Gilbert" , peterx@redhat.com, Juan Quintela Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: "Qemu-devel" X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Logically below race could trigger with the old code: test program migration thread ------------ ---------------- wait_until('postcopy-pause') postcopy_pause() set_state('postcopy-pause') do_postcopy_recover() arm s->to_dst_file with new fd release s->to_dst_file [1] Here [1] could have released the just-installed recoverying channel. Then = the migration could hang without really resuming. Instead, it should be very safe to release the fd before setting the state = into 'postcopy-pause', because there's no reason for any other thread to touch it during 'postcopy-active'. Dave reported a very rare postcopy recovery hang that the migration-test program waited for the migration to complete in migrate_postcopy_complete(). We do suspect it's the same thing that we're gonna fix here. Hard to tell. However since we've noticed this, fix this irrelevant of the hang report. Cc: Dr. David Alan Gilbert Cc: Juan Quintela Signed-off-by: Peter Xu --- migration/migration.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index aca7fdcd0b..e1b06e8a2a 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -3137,9 +3137,6 @@ static MigThrError postcopy_pause(MigrationState *s) while (true) { QEMUFile *file; =20 - migrate_set_state(&s->state, s->state, - MIGRATION_STATUS_POSTCOPY_PAUSED); - /* Current channel is possibly broken. Release it. */ assert(s->to_dst_file); qemu_mutex_lock(&s->qemu_file_lock); @@ -3150,6 +3147,9 @@ static MigThrError postcopy_pause(MigrationState *s) qemu_file_shutdown(file); qemu_fclose(file); =20 + migrate_set_state(&s->state, s->state, + MIGRATION_STATUS_POSTCOPY_PAUSED); + error_report("Detected IO failure for postcopy. " "Migration paused."); =20 --=20 2.26.2