From patchwork Tue Feb 18 10:55:15 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhang Yi X-Patchwork-Id: 231174 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=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, 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 E221CC34038 for ; Tue, 18 Feb 2020 10:56:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C09EA206E2 for ; Tue, 18 Feb 2020 10:56:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726403AbgBRK4j (ORCPT ); Tue, 18 Feb 2020 05:56:39 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:10636 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726496AbgBRK4i (ORCPT ); Tue, 18 Feb 2020 05:56:38 -0500 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 6D391E9C42D8BE5EA82B; Tue, 18 Feb 2020 18:56:35 +0800 (CST) Received: from huawei.com (10.175.124.28) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.439.0; Tue, 18 Feb 2020 18:56:25 +0800 From: "zhangyi (F)" To: CC: , , , , Subject: [PATCH 4.4 2/2] jbd2: do not clear the BH_Mapped flag when forgetting a metadata buffer Date: Tue, 18 Feb 2020 18:55:15 +0800 Message-ID: <20200218105515.6548-2-yi.zhang@huawei.com> X-Mailer: git-send-email 2.17.2 In-Reply-To: <20200218105515.6548-1-yi.zhang@huawei.com> References: <20200218105515.6548-1-yi.zhang@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.124.28] X-CFilter-Loop: Reflected Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org [ Upstream commit c96dceeabf765d0b1b1f29c3bf50a5c01315b820 ] Commit 904cdbd41d74 ("jbd2: clear dirty flag when revoking a buffer from an older transaction") set the BH_Freed flag when forgetting a metadata buffer which belongs to the committing transaction, it indicate the committing process clear dirty bits when it is done with the buffer. But it also clear the BH_Mapped flag at the same time, which may trigger below NULL pointer oops when block_size < PAGE_SIZE. rmdir 1 kjournald2 mkdir 2 jbd2_journal_commit_transaction commit transaction N jbd2_journal_forget set_buffer_freed(bh1) jbd2_journal_commit_transaction commit transaction N+1 ... clear_buffer_mapped(bh1) ext4_getblk(bh2 ummapped) ... grow_dev_page init_page_buffers bh1->b_private=NULL bh2->b_private=NULL jbd2_journal_put_journal_head(jh1) __journal_remove_journal_head(hb1) jh1 is NULL and trigger oops *) Dir entry block bh1 and bh2 belongs to one page, and the bh2 has already been unmapped. For the metadata buffer we forgetting, we should always keep the mapped flag and clear the dirty flags is enough, so this patch pick out the these buffers and keep their BH_Mapped flag. Link: https://lore.kernel.org/r/20200213063821.30455-3-yi.zhang@huawei.com Fixes: 904cdbd41d74 ("jbd2: clear dirty flag when revoking a buffer from an older transaction") Reviewed-by: Jan Kara Signed-off-by: zhangyi (F) Signed-off-by: Theodore Ts'o Cc: stable@kernel.org --- fs/jbd2/commit.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index 3bf86d912b76..7fe61edb1bb9 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -996,12 +996,29 @@ restart_loop: * pagesize and it is attached to the last partial page. */ if (buffer_freed(bh) && !jh->b_next_transaction) { + struct address_space *mapping; + clear_buffer_freed(bh); clear_buffer_jbddirty(bh); - clear_buffer_mapped(bh); - clear_buffer_new(bh); - clear_buffer_req(bh); - bh->b_bdev = NULL; + + /* + * Block device buffers need to stay mapped all the + * time, so it is enough to clear buffer_jbddirty and + * buffer_freed bits. For the file mapping buffers (i.e. + * journalled data) we need to unmap buffer and clear + * more bits. We also need to be careful about the check + * because the data page mapping can get cleared under + * out hands, which alse need not to clear more bits + * because the page and buffers will be freed and can + * never be reused once we are done with them. + */ + mapping = READ_ONCE(bh->b_page->mapping); + if (mapping && !sb_is_blkdev_sb(mapping->host->i_sb)) { + clear_buffer_mapped(bh); + clear_buffer_new(bh); + clear_buffer_req(bh); + bh->b_bdev = NULL; + } } if (buffer_jbddirty(bh)) {