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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 07DBBCCA47C for ; Tue, 7 Jun 2022 19:47:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356385AbiFGTrf (ORCPT ); Tue, 7 Jun 2022 15:47:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32878 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1353706AbiFGSrp (ORCPT ); Tue, 7 Jun 2022 14:47:45 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0C484106A5D; Tue, 7 Jun 2022 11:03:05 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 3F4E7B8237D; Tue, 7 Jun 2022 18:03:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D17BFC36AFE; Tue, 7 Jun 2022 18:03:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1654624982; bh=iWBOTEh3pfVschnPE9YDhi6e6oeQzoGIRIWzTCrrtMc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=erWFSyCET9YhOnEHvVBA9xi2kpxvQl6uWWjVG1inBLEAJxfp8W3UcfbyAkwK7ybQW qOIYp1NafWmuAtBYYteda/9Y4FyyWvp5XsYM8N2EFWbbY1U5mvpNopE7ejRaP2ml5j TZYxbvp8TY1aIXL+1YMqV1aLAsGK1cdvpaNY84iNBTFQR4Ul+vAGJrBuHt726rBDPS K3NbJM6PfGBXr32tgsI6cwrJZDpv73qkrrmDST18WPUkTw9Dc2BwaabvSCoxzpAJeS Sm2qfYhJ7XsoYtFqPONFYXXr0E1iQT88GGgmRsYupttqodrC47ecyBfY5yGT/jKBKY y9luPcCw9hAFw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Guoqing Jiang , Donald Buczek , Song Liu , Sasha Levin , agk@redhat.com, snitzer@kernel.org, dm-devel@redhat.com, linux-raid@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 17/25] md: don't unregister sync_thread with reconfig_mutex held Date: Tue, 7 Jun 2022 14:02:18 -0400 Message-Id: <20220607180229.482040-17-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220607180229.482040-1-sashal@kernel.org> References: <20220607180229.482040-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Guoqing Jiang [ Upstream commit 8b48ec23cc51a4e7c8dbaef5f34ebe67e1a80934 ] 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 Signed-off-by: Song Liu Signed-off-by: Sasha Levin --- 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 2c5912e75514..c334a0b0b708 100644 --- a/drivers/md/dm-raid.c +++ b/drivers/md/dm-raid.c @@ -3569,7 +3569,7 @@ 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 (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) || test_bit(MD_RECOVERY_NEEDED, &mddev->recovery)) diff --git a/drivers/md/md.c b/drivers/md/md.c index 5e8706a66c31..85bccc53fdd1 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -4587,7 +4587,7 @@ 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); } @@ -5842,7 +5842,7 @@ 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); @@ -8837,7 +8837,7 @@ 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); @@ -8872,7 +8872,7 @@ 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 @@ -8945,12 +8945,16 @@ 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; + if (reconfig_mutex_held) + mddev_unlock(mddev); /* resync has finished, collect result */ 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 69bc0d5550cd..09042e409c51 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -668,7 +668,7 @@ 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); -- 2.35.1