From patchwork Tue Nov 3 20:37:22 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 317037 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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 EE9F2C388F7 for ; Tue, 3 Nov 2020 21:14:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 919EF206B5 for ; Tue, 3 Nov 2020 21:14:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604438089; bh=IKLkAKmnVzunT9+Lx2pzNpm6lquDnEOLwyezfeKvbas=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OBNM92pivtvy9PJ9L0w7iSJ3OHbmKRMXLzC1MdODwyasxyHjGCzUp7bMguC0YE8Ql vzdkJuH7nLuTQ6wKrd0UV41vXUcmAOs9ZQUIHeniRraHF1E1K4jocAQtgbLJcY5AEU eskmwoLZNT+HUIY2Ol7u2TMMfc7iW5iD2HAYxPs0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389034AbgKCVMf (ORCPT ); Tue, 3 Nov 2020 16:12:35 -0500 Received: from mail.kernel.org ([198.145.29.99]:54980 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389005AbgKCVMe (ORCPT ); Tue, 3 Nov 2020 16:12:34 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 094B6206B5; Tue, 3 Nov 2020 21:12:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604437953; bh=IKLkAKmnVzunT9+Lx2pzNpm6lquDnEOLwyezfeKvbas=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MwXYT2a8jOqhte1p97HCcRAUncQwdaFH51Ojt2TWYOAt30gtiWxEB6KoHgtlRwGkV 7TzBsZd+h/xqTJJ0eOes5G/8zv8pzbidvLcTrEakxriydXh9vmuwJPSBNtbq8TB0yN bkrct03PrxSPsTQqy/Att0+agPitED3xFL67JhxM= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ye Bin , Jan Kara , Christoph Hellwig , Jens Axboe Subject: [PATCH 4.14 065/125] fs: Dont invalidate page buffers in block_write_full_page() Date: Tue, 3 Nov 2020 21:37:22 +0100 Message-Id: <20201103203206.306248248@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201103203156.372184213@linuxfoundation.org> References: <20201103203156.372184213@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Jan Kara commit 6dbf7bb555981fb5faf7b691e8f6169fc2b2e63b upstream. If block_write_full_page() is called for a page that is beyond current inode size, it will truncate page buffers for the page and return 0. This logic has been added in 2.5.62 in commit 81eb69062588 ("fix ext3 BUG due to race with truncate") in history.git tree to fix a problem with ext3 in data=ordered mode. This particular problem doesn't exist anymore because ext3 is long gone and ext4 handles ordered data differently. Also normally buffers are invalidated by truncate code and there's no need to specially handle this in ->writepage() code. This invalidation of page buffers in block_write_full_page() is causing issues to filesystems (e.g. ext4 or ocfs2) when block device is shrunk under filesystem's hands and metadata buffers get discarded while being tracked by the journalling layer. Although it is obviously "not supported" it can cause kernel crashes like: [ 7986.689400] BUG: unable to handle kernel NULL pointer dereference at +0000000000000008 [ 7986.697197] PGD 0 P4D 0 [ 7986.699724] Oops: 0002 [#1] SMP PTI [ 7986.703200] CPU: 4 PID: 203778 Comm: jbd2/dm-3-8 Kdump: loaded Tainted: G +O --------- - - 4.18.0-147.5.0.5.h126.eulerosv2r9.x86_64 #1 [ 7986.716438] Hardware name: Huawei RH2288H V3/BC11HGSA0, BIOS 1.57 08/11/2015 [ 7986.723462] RIP: 0010:jbd2_journal_grab_journal_head+0x1b/0x40 [jbd2] ... [ 7986.810150] Call Trace: [ 7986.812595] __jbd2_journal_insert_checkpoint+0x23/0x70 [jbd2] [ 7986.818408] jbd2_journal_commit_transaction+0x155f/0x1b60 [jbd2] [ 7986.836467] kjournald2+0xbd/0x270 [jbd2] which is not great. The crash happens because bh->b_private is suddently NULL although BH_JBD flag is still set (this is because block_invalidatepage() cleared BH_Mapped flag and subsequent bh lookup found buffer without BH_Mapped set, called init_page_buffers() which has rewritten bh->b_private). So just remove the invalidation in block_write_full_page(). Note that the buffer cache invalidation when block device changes size is already careful to avoid similar problems by using invalidate_mapping_pages() which skips busy buffers so it was only this odd block_write_full_page() behavior that could tear down bdev buffers under filesystem's hands. Reported-by: Ye Bin Signed-off-by: Jan Kara Reviewed-by: Christoph Hellwig CC: stable@vger.kernel.org Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- fs/buffer.c | 16 ---------------- 1 file changed, 16 deletions(-) --- a/fs/buffer.c +++ b/fs/buffer.c @@ -2799,16 +2799,6 @@ int nobh_writepage(struct page *page, ge /* Is the page fully outside i_size? (truncate in progress) */ offset = i_size & (PAGE_SIZE-1); if (page->index >= end_index+1 || !offset) { - /* - * The page may have dirty, unmapped buffers. For example, - * they may have been added in ext3_writepage(). Make them - * freeable here, so the page does not leak. - */ -#if 0 - /* Not really sure about this - do we need this ? */ - if (page->mapping->a_ops->invalidatepage) - page->mapping->a_ops->invalidatepage(page, offset); -#endif unlock_page(page); return 0; /* don't care */ } @@ -3003,12 +2993,6 @@ int block_write_full_page(struct page *p /* Is the page fully outside i_size? (truncate in progress) */ offset = i_size & (PAGE_SIZE-1); if (page->index >= end_index+1 || !offset) { - /* - * The page may have dirty, unmapped buffers. For example, - * they may have been added in ext3_writepage(). Make them - * freeable here, so the page does not leak. - */ - do_invalidatepage(page, 0, PAGE_SIZE); unlock_page(page); return 0; /* don't care */ }