From patchwork Mon Feb 8 15:01:41 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 379116 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=-19.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, 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 64526C433E0 for ; Mon, 8 Feb 2021 15:36:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2286164E37 for ; Mon, 8 Feb 2021 15:36:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234004AbhBHPgm (ORCPT ); Mon, 8 Feb 2021 10:36:42 -0500 Received: from mail.kernel.org ([198.145.29.99]:37400 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233901AbhBHPbc (ORCPT ); Mon, 8 Feb 2021 10:31:32 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 17F7F64EBA; Mon, 8 Feb 2021 15:17:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1612797447; bh=O2yhIxqh1eWICdYng4/cLd7KTROo58VCiHhBXMXZe4M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=oC3hh2sy2jZMuG8Qi54JYGGgT6AK/oYAocchcD01HXx3TtjIsXewupyGyTHCvyH/6 le0jaHAVNAd0yTo9XDFwXBxzU/xdZ2j/pVNx5gOjiWreGLf8Nof3vzGR3fZV6HHG9w i8l1g3F4jSTZA0gVjDwPiI0z4457MuA+HW2aXmDM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Jeffery , Xiao Ni , Song Liu , Jack Wang Subject: [PATCH 5.10 114/120] md: Set prev_flush_start and flush_bio in an atomic way Date: Mon, 8 Feb 2021 16:01:41 +0100 Message-Id: <20210208145822.912821175@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210208145818.395353822@linuxfoundation.org> References: <20210208145818.395353822@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Xiao Ni commit dc5d17a3c39b06aef866afca19245a9cfb533a79 upstream. One customer reports a crash problem which causes by flush request. It triggers a warning before crash. /* new request after previous flush is completed */ if (ktime_after(req_start, mddev->prev_flush_start)) { WARN_ON(mddev->flush_bio); mddev->flush_bio = bio; bio = NULL; } The WARN_ON is triggered. We use spin lock to protect prev_flush_start and flush_bio in md_flush_request. But there is no lock protection in md_submit_flush_data. It can set flush_bio to NULL first because of compiler reordering write instructions. For example, flush bio1 sets flush bio to NULL first in md_submit_flush_data. An interrupt or vmware causing an extended stall happen between updating flush_bio and prev_flush_start. Because flush_bio is NULL, flush bio2 can get the lock and submit to underlayer disks. Then flush bio1 updates prev_flush_start after the interrupt or extended stall. Then flush bio3 enters in md_flush_request. The start time req_start is behind prev_flush_start. The flush_bio is not NULL(flush bio2 hasn't finished). So it can trigger the WARN_ON now. Then it calls INIT_WORK again. INIT_WORK() will re-initialize the list pointers in the work_struct, which then can result in a corrupted work list and the work_struct queued a second time. With the work list corrupted, it can lead in invalid work items being used and cause a crash in process_one_work. We need to make sure only one flush bio can be handled at one same time. So add spin lock in md_submit_flush_data to protect prev_flush_start and flush_bio in an atomic way. Reviewed-by: David Jeffery Signed-off-by: Xiao Ni Signed-off-by: Song Liu Signed-off-by: Jack Wang Signed-off-by: Greg Kroah-Hartman --- drivers/md/md.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -639,8 +639,10 @@ static void md_submit_flush_data(struct * could wait for this and below md_handle_request could wait for those * bios because of suspend check */ + spin_lock_irq(&mddev->lock); mddev->last_flush = mddev->start_flush; mddev->flush_bio = NULL; + spin_unlock_irq(&mddev->lock); wake_up(&mddev->sb_wait); if (bio->bi_iter.bi_size == 0) {