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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 77332C43381 for ; Mon, 1 Apr 2019 17:52:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 48E2720830 for ; Mon, 1 Apr 2019 17:52:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554141141; bh=4PZrWirNAMBsE96chJdqVISjpI4SqRDJaPIRbfwIib8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=jLcJEoVVGK5cLRFqslKEELzE8N6/5LHoBYZGe29VV0NTibSNFveBlrMkZfCcyUvBc n7qyzINVQZjDugbYSJ08L42C7C7ZirBROMEesqdQCyzZvHR2qs00wbzPaSgLJLbBJ3 wSBVdRlSmdPXiLUV4IwvzDmtfakKKRfEZ6S2s1A0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732763AbfDARwU (ORCPT ); Mon, 1 Apr 2019 13:52:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:59156 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731559AbfDAR0r (ORCPT ); Mon, 1 Apr 2019 13:26:47 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 64F7720830; Mon, 1 Apr 2019 17:26:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554139606; bh=4PZrWirNAMBsE96chJdqVISjpI4SqRDJaPIRbfwIib8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S3U9YYZUR9F/bsyG+DdDqO9OxZ0unE/7D2asPuTQrfH/xN4FL9lEy6kwXvOSbVjow 5Yj1dhMZFxDDaeFKIgE8JRM9tB72hZe6fHZLd5pqRHHIq9QPwhaUl1zrQtwKRq0g7V 1CtWH69LnlEYD5QTTKcgtLnin1HAQ4YHllLteDio= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Johannes Thumshirn , Andrea Righi , David Sterba Subject: [PATCH 4.9 18/56] btrfs: raid56: properly unmap parity page in finish_parity_scrub() Date: Mon, 1 Apr 2019 19:02:34 +0200 Message-Id: <20190401170104.821355837@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190401170103.398401360@linuxfoundation.org> References: <20190401170103.398401360@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Andrea Righi commit 3897b6f0a859288c22fb793fad11ec2327e60fcd upstream. Parity page is incorrectly unmapped in finish_parity_scrub(), triggering a reference counter bug on i386, i.e.: [ 157.662401] kernel BUG at mm/highmem.c:349! [ 157.666725] invalid opcode: 0000 [#1] SMP PTI The reason is that kunmap(p_page) was completely left out, so we never did an unmap for the p_page and the loop unmapping the rbio page was iterating over the wrong number of stripes: unmapping should be done with nr_data instead of rbio->real_stripes. Test case to reproduce the bug: - create a raid5 btrfs filesystem: # mkfs.btrfs -m raid5 -d raid5 /dev/sdb /dev/sdc /dev/sdd /dev/sde - mount it: # mount /dev/sdb /mnt - run btrfs scrub in a loop: # while :; do btrfs scrub start -BR /mnt; done BugLink: https://bugs.launchpad.net/bugs/1812845 Fixes: 5a6ac9eacb49 ("Btrfs, raid56: support parity scrub on raid56") CC: stable@vger.kernel.org # 4.4+ Reviewed-by: Johannes Thumshirn Signed-off-by: Andrea Righi Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/raid56.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/fs/btrfs/raid56.c +++ b/fs/btrfs/raid56.c @@ -2395,8 +2395,9 @@ static noinline void finish_parity_scrub bitmap_clear(rbio->dbitmap, pagenr, 1); kunmap(p); - for (stripe = 0; stripe < rbio->real_stripes; stripe++) + for (stripe = 0; stripe < nr_data; stripe++) kunmap(page_in_rbio(rbio, stripe, pagenr, 0)); + kunmap(p_page); } __free_page(p_page);