From patchwork Wed Jan 24 09:14:12 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 13528824 X-Patchwork-Delegate: snitzer@redhat.com Received: from szxga04-in.huawei.com (szxga04-in.huawei.com [45.249.212.190]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BD2BA17C65 for ; Wed, 24 Jan 2024 09:19:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.190 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706087954; cv=none; b=DUf0E5Lqj4fz8Ammzw+SzlZ7bSm34RM5ZJIYaXEd44wUTydrBkcPHXMSrX383dX+DqMEz1Y5GD4/g+C+6jaVWGLt0DSeoJEBtWMzCyVvpTBfw0PES647sSYGiz9AIoW/RQHIJwBL5M76W3/SWu+iaoLq9wG/I2o0BdgP3znY8X8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706087954; c=relaxed/simple; bh=X18KtNk96NC0AqflJWJCrao6h9w3a7IJOBSuBGFV//o=; h=From:To:CC:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=u9/+RoT/AQaq4LCoTS3Pl/GPFJDKldSrvlbC6nNG+dlTOWGW9Emop3YUVlzIHQpHvprf5vBhZdsfYRQCRYCSMra2nO4jEd6tmP9P/KXQmCMR2wctBGQPkp7EZbmZeHbvROp3aDS1NKwecFq0vVBDYTJF/WdobHzWLp1L56XB5RM= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.190 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.214]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4TKdfT6qvxz1xmZt; Wed, 24 Jan 2024 17:18:09 +0800 (CST) Received: from kwepemm600009.china.huawei.com (unknown [7.193.23.164]) by mail.maildlp.com (Postfix) with ESMTPS id 53C0F1A017B; Wed, 24 Jan 2024 17:18:47 +0800 (CST) Received: from huawei.com (10.175.104.67) by kwepemm600009.china.huawei.com (7.193.23.164) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.35; Wed, 24 Jan 2024 17:18:18 +0800 From: Yu Kuai To: , , , , , , , , , , , CC: , , , , Subject: [PATCH v2 02/11] md: don't ignore read-only array in md_check_recovery() Date: Wed, 24 Jan 2024 17:14:12 +0800 Message-ID: <20240124091421.1261579-3-yukuai3@huawei.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240124091421.1261579-1-yukuai3@huawei.com> References: <20240124091421.1261579-1-yukuai3@huawei.com> Precedence: bulk X-Mailing-List: dm-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemm600009.china.huawei.com (7.193.23.164) Usually if the array is not read-write, md_check_recovery() won't register new sync_thread in the first place. And if the array is read-write and sync_thread is registered, md_set_readonly() will unregister sync_thread before setting the array read-only. md/raid follow this behavior hence there is no problem. After commit f52f5c71f3d4 ("md: fix stopping sync thread"), following hang can be triggered by test shell/integrity-caching.sh: 1) array is read-only. dm-raid update super block: rs_update_sbs ro = mddev->ro mddev->ro = 0 -> set array read-write md_update_sb 2) register new sync thread concurrently. 3) dm-raid set array back to read-only: rs_update_sbs mddev->ro = ro 4) stop the array: raid_dtr md_stop stop_sync_thread set_bit(MD_RECOVERY_INTR, &mddev->recovery); md_wakeup_thread_directly(mddev->sync_thread); wait_event(..., !test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) 5) sync thread done: md_do_sync set_bit(MD_RECOVERY_DONE, &mddev->recovery); md_wakeup_thread(mddev->thread); 6) daemon thread can't unregister sync thread: md_check_recovery if (!md_is_rdwr(mddev) && !test_bit(MD_RECOVERY_NEEDED, &mddev->recovery)) return; -> -> MD_RECOVERY_RUNNING can't be cleared, hence step 4 hang; The root cause is that dm-raid manipulate 'mddev->ro' by itself, however, dm-raid really should stop sync thread before setting the array read-only. Unfortunately, I need to read more code before I can refacter the handler of 'mddev->ro' in dm-raid, hence let's fix the problem the easy way for now to prevent dm-raid regression. Reported-by: Mikulas Patocka Closes: https://lore.kernel.org/all/9801e40-8ac7-e225-6a71-309dcf9dc9aa@redhat.com/ Fixes: ecbfb9f118bc ("dm raid: add raid level takeover support") Fixes: f52f5c71f3d4 ("md: fix stopping sync thread") Signed-off-by: Yu Kuai --- drivers/md/md.c | 31 ++++++++++++++++++------------- 1 file changed, 18 insertions(+), 13 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 07b80278eaa5..6906d023f1d6 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -9445,6 +9445,20 @@ static void md_start_sync(struct work_struct *ws) sysfs_notify_dirent_safe(mddev->sysfs_action); } +static void unregister_sync_thread(struct mddev *mddev) +{ + if (!test_bit(MD_RECOVERY_DONE, &mddev->recovery)) { + /* resync/recovery still happening */ + clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery); + return; + } + + if (WARN_ON_ONCE(!mddev->sync_thread)) + return; + + md_reap_sync_thread(mddev); +} + /* * This routine is regularly called by all per-raid-array threads to * deal with generic issues like resync and super-block update. @@ -9482,7 +9496,8 @@ void md_check_recovery(struct mddev *mddev) } if (!md_is_rdwr(mddev) && - !test_bit(MD_RECOVERY_NEEDED, &mddev->recovery)) + !test_bit(MD_RECOVERY_NEEDED, &mddev->recovery) && + !test_bit(MD_RECOVERY_DONE, &mddev->recovery)) return; if ( ! ( (mddev->sb_flags & ~ (1<recovery)) { - /* sync_work already queued. */ - clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery); + unregister_sync_thread(mddev); goto unlock; } @@ -9568,16 +9582,7 @@ void md_check_recovery(struct mddev *mddev) * still set. */ if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery)) { - if (!test_bit(MD_RECOVERY_DONE, &mddev->recovery)) { - /* resync/recovery still happening */ - clear_bit(MD_RECOVERY_NEEDED, &mddev->recovery); - goto unlock; - } - - if (WARN_ON_ONCE(!mddev->sync_thread)) - goto unlock; - - md_reap_sync_thread(mddev); + unregister_sync_thread(mddev); goto unlock; }