From patchwork Fri May 26 11:59:08 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fiona Ebner X-Patchwork-Id: 13256848 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 2C961C77B7A for ; Fri, 26 May 2023 11:59:33 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1q2W6O-0001eE-0T; Fri, 26 May 2023 07:59:24 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1q2W6M-0001e5-1B for qemu-devel@nongnu.org; Fri, 26 May 2023 07:59:22 -0400 Received: from proxmox-new.maurer-it.com ([94.136.29.106]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1q2W6K-0001lE-7i for qemu-devel@nongnu.org; Fri, 26 May 2023 07:59:21 -0400 Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id CC41A4737D; Fri, 26 May 2023 13:59:14 +0200 (CEST) From: Fiona Ebner To: qemu-devel@nongnu.org Cc: andrey.gruzdev@virtuozzo.com, quintela@redhat.com, peterx@redhat.com, leobras@redhat.com Subject: [PATCH] migration: stop tracking ram writes when cancelling background migration Date: Fri, 26 May 2023 13:59:08 +0200 Message-Id: <20230526115908.196171-1-f.ebner@proxmox.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 Received-SPF: pass client-ip=94.136.29.106; envelope-from=f.ebner@proxmox.com; helo=proxmox-new.maurer-it.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Currently, it is only done when the iteration finishes successfully. Not cleaning up the userfaultfd write protection can lead to symptoms/issues such as the process hanging in memmove or GDB not being able to attach. Signed-off-by: Fiona Ebner Reviewed-by: Peter Xu Reviewed-by: Juan Quintela --- For the success case, the stuff in between the old call and new call site should not depend on tracking to already be stopped, right? AFAICS, it's just some QEMU file operations and manipulation of migration state and counters, but I have only limited knowledge, so I thought I'd better ask :) migration/migration.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/migration/migration.c b/migration/migration.c index 5de7f734b9..60583699f7 100644 --- a/migration/migration.c +++ b/migration/migration.c @@ -2400,13 +2400,6 @@ static void bg_migration_completion(MigrationState *s) { int current_active_state = s->state; - /* - * Stop tracking RAM writes - un-protect memory, un-register UFFD - * memory ranges, flush kernel wait queues and wake up threads - * waiting for write fault to be resolved. - */ - ram_write_tracking_stop(); - if (s->state == MIGRATION_STATUS_ACTIVE) { /* * By this moment we have RAM content saved into the migration stream. @@ -2788,6 +2781,13 @@ static void migration_iteration_finish(MigrationState *s) static void bg_migration_iteration_finish(MigrationState *s) { + /* + * Stop tracking RAM writes - un-protect memory, un-register UFFD + * memory ranges, flush kernel wait queues and wake up threads + * waiting for write fault to be resolved. + */ + ram_write_tracking_stop(); + qemu_mutex_lock_iothread(); switch (s->state) { case MIGRATION_STATUS_COMPLETED: