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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 985CFC433EF for ; Mon, 30 May 2022 02:12:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232202AbiE3CM4 (ORCPT ); Sun, 29 May 2022 22:12:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46364 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231473AbiE3CMy (ORCPT ); Sun, 29 May 2022 22:12:54 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 89BF95933B; Sun, 29 May 2022 19:12:51 -0700 (PDT) Received: from dggpeml500020.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4LBJmc6vFjz1JC2B; Mon, 30 May 2022 10:11:12 +0800 (CST) Received: from [10.174.177.174] (10.174.177.174) by dggpeml500020.china.huawei.com (7.185.36.88) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Mon, 30 May 2022 10:12:48 +0800 Message-ID: <881d1758-4594-c451-3dcc-e43c8e8b37f6@huawei.com> Date: Mon, 30 May 2022 10:12:48 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Subject: Re: [PATCH v3 1/3] ext4: fix bug_on ext4_mb_use_inode_pa To: Ritesh Harjani CC: , , , , , , , , , Hulk Robot , Baokun Li References: <20220528110017.354175-1-libaokun1@huawei.com> <20220528110017.354175-2-libaokun1@huawei.com> <20220528151044.u3quqpy4krsfwszq@riteshh-domain> From: Baokun Li In-Reply-To: <20220528151044.u3quqpy4krsfwszq@riteshh-domain> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.174] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To dggpeml500020.china.huawei.com (7.185.36.88) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 在 2022/5/28 23:10, Ritesh Harjani 写道: > On 22/05/28 07:00PM, Baokun Li wrote: >> Hulk Robot reported a BUG_ON: >> ================================================================== >> kernel BUG at fs/ext4/mballoc.c:3211! >> [...] >> RIP: 0010:ext4_mb_mark_diskspace_used.cold+0x85/0x136f >> [...] >> Call Trace: >> ext4_mb_new_blocks+0x9df/0x5d30 >> ext4_ext_map_blocks+0x1803/0x4d80 >> ext4_map_blocks+0x3a4/0x1a10 >> ext4_writepages+0x126d/0x2c30 >> do_writepages+0x7f/0x1b0 >> __filemap_fdatawrite_range+0x285/0x3b0 >> file_write_and_wait_range+0xb1/0x140 >> ext4_sync_file+0x1aa/0xca0 >> vfs_fsync_range+0xfb/0x260 >> do_fsync+0x48/0xa0 >> [...] >> ================================================================== >> >> Above issue may happen as follows: >> ------------------------------------- >> do_fsync >> vfs_fsync_range >> ext4_sync_file >> file_write_and_wait_range >> __filemap_fdatawrite_range >> do_writepages >> ext4_writepages >> mpage_map_and_submit_extent >> mpage_map_one_extent >> ext4_map_blocks >> ext4_mb_new_blocks >> ext4_mb_normalize_request >> >>> start + size <= ac->ac_o_ex.fe_logical >> ext4_mb_regular_allocator >> ext4_mb_simple_scan_group >> ext4_mb_use_best_found >> ext4_mb_new_preallocation >> ext4_mb_new_inode_pa >> ext4_mb_use_inode_pa >> >>> set ac->ac_b_ex.fe_len <= 0 >> ext4_mb_mark_diskspace_used >> >>> BUG_ON(ac->ac_b_ex.fe_len <= 0); >> >> we can easily reproduce this problem with the following commands: >> `fallocate -l100M disk` >> `mkfs.ext4 -b 1024 -g 256 disk` >> `mount disk /mnt` >> `fsstress -d /mnt -l 0 -n 1000 -p 1` >> >> The size must be smaller than or equal to EXT4_BLOCKS_PER_GROUP. >> Therefore, "start + size <= ac->ac_o_ex.fe_logical" may occur >> when the size is truncated. So start should be the start position of >> the group where ac_o_ex.fe_logical is located after alignment. >> In addition, when the value of fe_logical or EXT4_BLOCKS_PER_GROUP >> is very large, the value calculated by start_off is more accurate. >> >> Fixes: cd648b8a8fd5 ("ext4: trim allocation requests to group size") >> Reported-by: Hulk Robot >> Signed-off-by: Baokun Li >> --- >> V1->V2: >> Replace round_down() with rounddown(). >> Modified comments. >> V2->V3: >> Convert EXT4_BLOCKS_PER_GROUP type to ext4_lblk_t >> to avoid compilation warnings. > Looks good to me. Feel free to add - > > Reviewed-by: Ritesh Harjani > >> fs/ext4/mballoc.c | 9 +++++++++ >> 1 file changed, 9 insertions(+) >> > . > Thank you for your review! -- With Best Regards, Baokun Li