From patchwork Wed Jan 17 18:22:36 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Mikulas Patocka X-Patchwork-Id: 13522088 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 3070022EE4 for ; Wed, 17 Jan 2024 18:22:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705515763; cv=none; b=DLi5ih7h7E5IKMen8MIgeTudBi/AX5tnrFiesJK0ZHz3ftU9UeIYTO+20g90Vx6XzOCFp73ItxUuZC76a+kZNDvVrcEtR5i3XMy9X9c9fLwZoZnc+gtCd1DZ3vB2kUAD/XH3U2IAyXZhes8n/p7xeWyg37HZ9PtLdqaMSpakxwY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1705515763; c=relaxed/simple; bh=V8R9j4TYEy4pGFHA0w+YlUVkrb0ecevYuEGI9WoaKco=; h=DKIM-Signature:Received:X-MC-Unique:Received:Received:Received: Received:Date:From:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type:X-Scanned-By; b=M2a7rcImGsXzWEznfVEvaPQMWVAC4KVRyDSPeQDgq4W+Amo6kbYUWMQ3hrdYKCvVesM0IYpbgRM2rxzhecas5H+y4luXGTHorvyjvqutMoLB2iCatX5PUvPvDOE6JAavn4s1EQRXxF/xNsHNc85t03RAfWje3jx44D2RU42kI0g= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=WPKFXq5f; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="WPKFXq5f" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1705515761; 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: in-reply-to:in-reply-to:references:references; bh=z09U/kH5aTZB7jjyJSH8zHLRV8pSgNSa2hUWXWZNzSg=; b=WPKFXq5fnr89y2q8muWwd7HBgrBPlEy3F6p/qborZz+7ax80FiW7APSoiNwVwHf9r/9owf 8W+w5Vo4cC1BRQQUcxg5twYnFiuI69x6N6Rb2FK/9tO+B5g40KbCsvVqp2mt9tEhbnhsFC 4QnT7rvnVIQXATjBHW1vnCm/aH5vuvw= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-241-ng3Nu4FMNIS2uCOcjaNjhg-1; Wed, 17 Jan 2024 13:22:36 -0500 X-MC-Unique: ng3Nu4FMNIS2uCOcjaNjhg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.rdu2.redhat.com [10.11.54.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 7B94F85A58B; Wed, 17 Jan 2024 18:22:36 +0000 (UTC) Received: from file1-rdu.file-001.prod.rdu2.dc.redhat.com (unknown [10.11.5.21]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 73FB13C27; Wed, 17 Jan 2024 18:22:36 +0000 (UTC) Received: by file1-rdu.file-001.prod.rdu2.dc.redhat.com (Postfix, from userid 12668) id 6B74830C039C; Wed, 17 Jan 2024 18:22:36 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by file1-rdu.file-001.prod.rdu2.dc.redhat.com (Postfix) with ESMTP id 6ABB53FB50; Wed, 17 Jan 2024 19:22:36 +0100 (CET) Date: Wed, 17 Jan 2024 19:22:36 +0100 (CET) From: Mikulas Patocka To: Yu Kuai , Song Liu , David Jeffery , Li Nan cc: dm-devel@lists.linux.dev, linux-raid@vger.kernel.org, Mike Snitzer , Heinz Mauelshagen , Benjamin Marzinski Subject: [PATCH 7/7] md: fix a suspicious RCU usage warning In-Reply-To: Message-ID: <51539879-e1ca-fde3-b8b4-8934ddedcbc@redhat.com> References: Precedence: bulk X-Mailing-List: linux-raid@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.1 RCU protection was removed in the commit 2d32777d60de ("raid1: remove rcu protection to access rdev from conf"). However, the code in fix_read_error does rcu_dereference outside rcu_read_lock - this triggers the following warning. The warning is triggered by a LVM2 test shell/integrity-caching.sh. This commit removes rcu_dereference. ============================= WARNING: suspicious RCU usage 6.7.0 #2 Not tainted ----------------------------- drivers/md/raid1.c:2265 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 no locks held by mdX_raid1/1859. stack backtrace: CPU: 2 PID: 1859 Comm: mdX_raid1 Not tainted 6.7.0 #2 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014 Call Trace: dump_stack_lvl+0x60/0x70 lockdep_rcu_suspicious+0x153/0x1b0 raid1d+0x1732/0x1750 [raid1] ? lock_acquire+0x9f/0x270 ? finish_wait+0x3d/0x80 ? md_thread+0xf7/0x130 [md_mod] ? lock_release+0xaa/0x230 ? md_register_thread+0xd0/0xd0 [md_mod] md_thread+0xa0/0x130 [md_mod] ? housekeeping_test_cpu+0x30/0x30 kthread+0xdc/0x110 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x28/0x40 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork_asm+0x11/0x20 Signed-off-by: Mikulas Patocka Fixes: ca294b34aaf3 ("md/raid1: support read error check") Reviewed-by: Yu Kuai --- drivers/md/raid1.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) Index: linux-2.6/drivers/md/raid1.c =================================================================== --- linux-2.6.orig/drivers/md/raid1.c +++ linux-2.6/drivers/md/raid1.c @@ -2262,7 +2262,7 @@ static void fix_read_error(struct r1conf int sectors = r1_bio->sectors; int read_disk = r1_bio->read_disk; struct mddev *mddev = conf->mddev; - struct md_rdev *rdev = rcu_dereference(conf->mirrors[read_disk].rdev); + struct md_rdev *rdev = conf->mirrors[read_disk].rdev; if (exceed_read_errors(mddev, rdev)) { r1_bio->bios[r1_bio->read_disk] = IO_BLOCKED;