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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,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 AE13DC43381 for ; Sat, 13 Feb 2021 00:51:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7B9F364E02 for ; Sat, 13 Feb 2021 00:51:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231883AbhBMAvC (ORCPT ); Fri, 12 Feb 2021 19:51:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57966 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231175AbhBMAvA (ORCPT ); Fri, 12 Feb 2021 19:51:00 -0500 Received: from mail-ed1-x530.google.com (mail-ed1-x530.google.com [IPv6:2a00:1450:4864:20::530]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6EDF7C061574 for ; Fri, 12 Feb 2021 16:50:19 -0800 (PST) Received: by mail-ed1-x530.google.com with SMTP id df22so1931682edb.1 for ; Fri, 12 Feb 2021 16:50:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloud.ionos.com; s=google; h=from:to:cc:subject:date:message-id; bh=Vjj9qYSvQfQbP8LLjapg+ws1IefrfhkmMhOgFWMI9Dc=; b=fAbGDvI1TGWPqn3td7hD3uOCkZf4pzLKmA3WZsUtAjKRG4gWfC6ZZk6Pd1FMJGoWS7 +A7ouz97ZPcaxOuZUsr1gjXTH2UIL7FSDEQUCRZE0emHUDXNdTUSr0qjkTjMtNhUH36L ydZlLAIN4WYkk/61UOAh/oEz+8q0JN2zsk6yJ6Mo+OEhrcvHTIXPaLdAo41ySifGVInH o7F6/YfiV+oDGeRSZ68CDUBTF3MruMCAdXP5VfJNUzDOrtHnc40CWS4LrENM18EaKYEx /HABoz8P0Y085huuwTaMi6Wg7fJzS3a/+4yG1rjViXmrPN1l0otdG8EXoCQCpdnrdEbW XArg== 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; bh=Vjj9qYSvQfQbP8LLjapg+ws1IefrfhkmMhOgFWMI9Dc=; b=nbvvcUeHKhTFDnadhtWla5+D/SUdp9vn7TwjQB/AuD/IEww5o7Inv6bs9ipWVHIjtP w77mWQhe0CCwHRI4UVl9qy7caFHU0U8/vYcrHIB3/8U51SxBtyePTl3nLAEDp9jUHTPg xx4t6eiw8NUChCL3MoIR1Vxw+G2XIQbltm0Ztg8QRkGcOM/DXQQH43FLMhwTYz7iVQVg 5hIdO8Y3HjfG9LRSGNgNaHri5ESto1jgh0PxQPCmKFqknbwNPfDYd7FratojsqTQqAVA e6WZGnd6uCvWLhf4rOTkAGIJ781l3Z7GRyTJDrCRieTCJlT/CzK683TbUIbwG6HEDzH+ 2HVQ== X-Gm-Message-State: AOAM531QyvT+g79bptVINS8OaYYNpler72N687KjYwjTJk/kdDz+vhGd E+57Sx6lkF8Y0qWq7gT+X9rOFQ== X-Google-Smtp-Source: ABdhPJwUUaMKuOdiJtXAePFBpMkAkKWzwNC9+NnwNOWYpuQaM5sgSKzXETgpdcKfunQ5LYMJm75ilQ== X-Received: by 2002:aa7:ce13:: with SMTP id d19mr6123370edv.208.1613177418112; Fri, 12 Feb 2021 16:50:18 -0800 (PST) Received: from gqjiang-home.profitbricks.net ([240e:304:2c81:30a4:4403:7938:f6d4:38b1]) by smtp.gmail.com with ESMTPSA id q10sm393817edr.51.2021.02.12.16.50.12 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Fri, 12 Feb 2021 16:50:17 -0800 (PST) From: Guoqing Jiang To: song@kernel.org Cc: agk@redhat.com, snitzer@redhat.com, linux-raid@vger.kernel.org, dm-devel@redhat.com, Guoqing Jiang Subject: [PATCH V2] md: don't unregister sync_thread with reconfig_mutex held Date: Sat, 13 Feb 2021 01:49:59 +0100 Message-Id: <1613177399-22024-1-git-send-email-guoqing.jiang@cloud.ionos.com> X-Mailer: git-send-email 2.7.4 Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org Unregister sync_thread doesn't need to hold reconfig_mutex since it doesn't reconfigure array. And it could cause deadlock problem for raid5 as follows: 1. process A tried to reap sync thread with reconfig_mutex held after echo idle to sync_action. 2. raid5 sync thread was blocked if there were too many active stripes. 3. SB_CHANGE_PENDING was set (because of write IO comes from upper layer) which causes the number of active stripes can't be decreased. 4. SB_CHANGE_PENDING can't be cleared since md_check_recovery was not able to hold reconfig_mutex. More details in the link: https://lore.kernel.org/linux-raid/5ed54ffc-ce82-bf66-4eff-390cb23bc1ac@molgen.mpg.de/T/#t And add one parameter to md_reap_sync_thread since it could be called by dm-raid which doesn't hold reconfig_mutex. Reported-and-tested-by: Donald Buczek Signed-off-by: Guoqing Jiang --- V2: 1. add one parameter to md_reap_sync_thread per Jack's suggestion. drivers/md/dm-raid.c | 2 +- drivers/md/md.c | 14 +++++++++----- drivers/md/md.h | 2 +- 3 files changed, 11 insertions(+), 7 deletions(-) diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c index cab12b2..0c4cbba 100644 --- a/drivers/md/dm-raid.c +++ b/drivers/md/dm-raid.c @@ -3668,7 +3668,7 @@ static int raid_message(struct dm_target *ti, unsigned int argc, char **argv, if (!strcasecmp(argv[0], "idle") || !strcasecmp(argv[0], "frozen")) { if (mddev->sync_thread) { set_bit(MD_RECOVERY_INTR, &mddev->recovery); - md_reap_sync_thread(mddev); + md_reap_sync_thread(mddev, false); } } else if (decipher_sync_action(mddev, mddev->recovery) != st_idle) return -EBUSY; diff --git a/drivers/md/md.c b/drivers/md/md.c index ca40942..0c12b7f 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -4857,7 +4857,7 @@ action_store(struct mddev *mddev, const char *page, size_t len) flush_workqueue(md_misc_wq); if (mddev->sync_thread) { set_bit(MD_RECOVERY_INTR, &mddev->recovery); - md_reap_sync_thread(mddev); + md_reap_sync_thread(mddev, true); } mddev_unlock(mddev); } @@ -6234,7 +6234,7 @@ static void __md_stop_writes(struct mddev *mddev) flush_workqueue(md_misc_wq); if (mddev->sync_thread) { set_bit(MD_RECOVERY_INTR, &mddev->recovery); - md_reap_sync_thread(mddev); + md_reap_sync_thread(mddev, true); } del_timer_sync(&mddev->safemode_timer); @@ -9256,7 +9256,7 @@ void md_check_recovery(struct mddev *mddev) * ->spare_active and clear saved_raid_disk */ set_bit(MD_RECOVERY_INTR, &mddev->recovery); - md_reap_sync_thread(mddev); + md_reap_sync_thread(mddev, true); clear_bit(MD_RECOVERY_RECOVER, &mddev->recovery); clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery); clear_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags); @@ -9291,7 +9291,7 @@ void md_check_recovery(struct mddev *mddev) goto unlock; } if (mddev->sync_thread) { - md_reap_sync_thread(mddev); + md_reap_sync_thread(mddev, true); goto unlock; } /* Set RUNNING before clearing NEEDED to avoid @@ -9364,14 +9364,18 @@ void md_check_recovery(struct mddev *mddev) } EXPORT_SYMBOL(md_check_recovery); -void md_reap_sync_thread(struct mddev *mddev) +void md_reap_sync_thread(struct mddev *mddev, bool reconfig_mutex_held) { struct md_rdev *rdev; sector_t old_dev_sectors = mddev->dev_sectors; bool is_reshaped = false; /* resync has finished, collect result */ + if (reconfig_mutex_held) + mddev_unlock(mddev); md_unregister_thread(&mddev->sync_thread); + if (reconfig_mutex_held) + mddev_lock_nointr(mddev); if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery) && !test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) && mddev->degraded != mddev->raid_disks) { diff --git a/drivers/md/md.h b/drivers/md/md.h index 34070ab..7ae3d98 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -705,7 +705,7 @@ extern struct md_thread *md_register_thread( extern void md_unregister_thread(struct md_thread **threadp); extern void md_wakeup_thread(struct md_thread *thread); extern void md_check_recovery(struct mddev *mddev); -extern void md_reap_sync_thread(struct mddev *mddev); +extern void md_reap_sync_thread(struct mddev *mddev, bool reconfig_mutex_held); extern int mddev_init_writes_pending(struct mddev *mddev); extern bool md_write_start(struct mddev *mddev, struct bio *bi); extern void md_write_inc(struct mddev *mddev, struct bio *bi); -- 2.7.4