From patchwork Mon Oct 19 22:57:19 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Xu X-Patchwork-Id: 270957 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=-12.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 6F740C433DF for ; Mon, 19 Oct 2020 22:59:13 +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 AE16122200 for ; Mon, 19 Oct 2020 22:59:12 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Afe/1H3+" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AE16122200 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:41906 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1kUe7T-0000UO-JH for qemu-devel@archiver.kernel.org; Mon, 19 Oct 2020 18:59:11 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:37512) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1kUe5w-00079p-MR for qemu-devel@nongnu.org; Mon, 19 Oct 2020 18:57:36 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:53363) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_CBC_SHA1:256) (Exim 4.90_1) (envelope-from ) id 1kUe5u-0005cx-Us for qemu-devel@nongnu.org; Mon, 19 Oct 2020 18:57:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1603148254; 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: in-reply-to:in-reply-to:references:references; bh=D5HFQfdM4TJN4VGII06GowLAi2up3lb9QwDK/dU70iw=; b=Afe/1H3+KGSmP8Fhbyrc2Hn9xU+osGPkewu+uT7jybk6tS3NUjkMlyuzwSGie3hGG4IJaU 3N9jknRfVf29YiRU27tbX1QOTUQCQ4XllOFPTNFo3X4SZy04KfXodD+/ZqAix5dMp95oZM 8AkA+Bk9ia7DGYaKqarER62Spap+dBc= Received: from mail-io1-f71.google.com (mail-io1-f71.google.com [209.85.166.71]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-595-_0hkHQUNMhWfvAPFDrrk8A-1; Mon, 19 Oct 2020 18:57:32 -0400 X-MC-Unique: _0hkHQUNMhWfvAPFDrrk8A-1 Received: by mail-io1-f71.google.com with SMTP id x13so1339695iom.10 for ; Mon, 19 Oct 2020 15:57:32 -0700 (PDT) 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:in-reply-to :references:mime-version:content-transfer-encoding; bh=D5HFQfdM4TJN4VGII06GowLAi2up3lb9QwDK/dU70iw=; b=Ep+qfYhMtuIBt4zrgD44D5fRDkhx3LLzdIFrroX7h5+MjbWER3tfLhtg6mQANn6U7/ B/LEvNij3Bw9uESdHATD7I/noh5uUxmJhndEDyghpAJPA7sZaWlY9DNY8nb4zpgbGrxF XI945oZ8UFpXplUPe3yDiV7kt0SbgMksj9f6qOS6c5omUnvhSd/Qzb86mhFAZKPYSlN6 lAeRPhx6ijD6Xcl5bXBfp8wRCGYwvefAQl8YtICCxgFGsWMM2t+dsDlK0GUSs1Os9DX+ A2xtnkUHIynfuf6M4cbtm/Zmrs48CwlrzfQU8BSUBPZcLF/yBfTR/Msms4vXYNNd1fkU KxUw== X-Gm-Message-State: AOAM532SgqTskQH5dve1LQZIhrrnhH7XgsgN9EqGTOP2OXH9DDHnn2GE wX9NQCOMi+vvGOPir5XcBHj96zQLw9vmQZB0Rt3mYQi59pLAfq+6lVYWRTDtZOlLgG1wCpa/95R ZykUMPFl/wq4B7Yo= X-Received: by 2002:a92:d709:: with SMTP id m9mr2053137iln.226.1603148251634; Mon, 19 Oct 2020 15:57:31 -0700 (PDT) X-Google-Smtp-Source: ABdhPJzrHKKdgocksKmW88BekSWF8FxFlKMkfhuGqm4kBj2vERLcVumo9AMK0xXE8x9yBFi7IoPJ8A== X-Received: by 2002:a92:d709:: with SMTP id m9mr2053121iln.226.1603148251321; Mon, 19 Oct 2020 15:57:31 -0700 (PDT) Received: from xz-x1.redhat.com (toroon474qw-lp140-04-174-95-215-133.dsl.bell.ca. [174.95.215.133]) by smtp.gmail.com with ESMTPSA id z89sm6017ilk.4.2020.10.19.15.57.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Oct 2020 15:57:30 -0700 (PDT) From: Peter Xu To: qemu-devel@nongnu.org Subject: [PATCH v5 5/6] migration/postcopy: Release fd before going into 'postcopy-pause' Date: Mon, 19 Oct 2020 18:57:19 -0400 Message-Id: <20201019225720.172743-6-peterx@redhat.com> X-Mailer: git-send-email 2.26.2 In-Reply-To: <20201019225720.172743-1-peterx@redhat.com> References: <20201019225720.172743-1-peterx@redhat.com> 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 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 = 2020/10/19 15:28:27 X-ACL-Warn: Detected OS = Linux 2.2.x-3.x [generic] [fuzzy] X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, 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: Peter Maydell , Thomas Huth , "Dr . David Alan Gilbert" , peterx@redhat.com, Juan Quintela Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" 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 Reviewed-by: Dr. David Alan Gilbert --- migration/migration.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index 0b4fcff01f..50df6251b7 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -3182,9 +3182,6 @@ static MigThrError postcopy_pause(MigrationState *s) while (true) { QEMUFile *file; - 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); @@ -3195,6 +3192,9 @@ static MigThrError postcopy_pause(MigrationState *s) qemu_file_shutdown(file); qemu_fclose(file); + migrate_set_state(&s->state, s->state, + MIGRATION_STATUS_POSTCOPY_PAUSED); + error_report("Detected IO failure for postcopy. " "Migration paused.");