From nobody Wed Dec 17 15:23:45 2025 Received: from dggsgout11.his.huawei.com (dggsgout11.his.huawei.com [45.249.212.51]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 083C82D05E; Thu, 22 Aug 2024 02:40:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.51 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724294442; cv=none; b=e1Piep9xk8l6NuVbXajq+1fsE37FiX5OlcIsrWwgUAWZZmF1EQUpSPCBCDs0kOUXwQbiJGuYr4P2ODI0PojkuoToHiRKDIE+OA8P2xgpbekWPszoXpJgPrrd6hIq/kOm8CqyhN+874i6GIbB2MhQvH4iyFIkQeylQ5cod96O9Fc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724294442; c=relaxed/simple; bh=Y2pikUM82WXAsiDFvKFLzeawwqDPF11vcLFNfXUXIKw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Ew/7Lx9zWQ5/K/oQK4CW9ilTRaCCyZkvhLh+gs0m7sgXTcvM+3/2B4mQtx72HSGnqsYLFAuXiRzPLwGFDWKblmfF1hU0HM4NqCefr8MJN0Oxd2yyC2BSQHPF6MMDAiLFYuVSef48xyHWQ1VVzQ5zctgr5/rdGt2EusI3F+xbU70= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.51 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.235]) by dggsgout11.his.huawei.com (SkyGuard) with ESMTP id 4Wq6r92b7bz4f3jt9; Thu, 22 Aug 2024 10:40:25 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 0FE461A0568; Thu, 22 Aug 2024 10:40:35 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgCHr4UapcZmqbd1CQ--.38129S12; Thu, 22 Aug 2024 10:40:34 +0800 (CST) From: libaokun@huaweicloud.com To: linux-ext4@vger.kernel.org Cc: tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.cz, ritesh.list@gmail.com, ojaswin@linux.ibm.com, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, libaokun@huaweicloud.com, Baokun Li , stable@kernel.org Subject: [PATCH v2 08/25] ext4: fix double brelse() the buffer of the extents path Date: Thu, 22 Aug 2024 10:35:28 +0800 Message-Id: <20240822023545.1994557-9-libaokun@huaweicloud.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240822023545.1994557-1-libaokun@huaweicloud.com> References: <20240822023545.1994557-1-libaokun@huaweicloud.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: gCh0CgCHr4UapcZmqbd1CQ--.38129S12 X-Coremail-Antispam: 1UD129KBjvJXoWxWF43AFyfJw1rWFW8XrWUurg_yoW5Ww4fpr sIkryxGr1rt3yq9FWDJF4UCr10k3W3Gw47JFWfC3WjkFyqyr4kXFy7K3WFvF98uFW8ZF4Y vFW8t34UW3Z8Ka7anT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUQ214x267AKxVWrJVCq3wAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2048vs2IY020E87I2jVAFwI0_JF0E3s1l82xGYI kIc2x26xkF7I0E14v26ryj6s0DM28lY4IEw2IIxxk0rwA2F7IY1VAKz4vEj48ve4kI8wA2 z4x0Y4vE2Ix0cI8IcVAFwI0_Ar0_tr1l84ACjcxK6xIIjxv20xvEc7CjxVAFwI0_Gr1j6F 4UJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0oVCq 3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VC0I7 IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j6r4U M4x0Y48IcxkI7VAKI48JM4x0x7Aq67IIx4CEVc8vx2IErcIFxwACI402YVCY1x02628vn2 kIc2xKxwAKzVCY07xG64k0F24lc7CjxVAaw2AFwI0_Jw0_GFyl42xK82IYc2Ij64vIr41l 4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s026x8GjcxK67 AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8I cVAFwI0_JFI_Gr1lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4UJVWxJr1lIxAIcVCF04k26c xKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2jsIEc7CjxVAF wI0_Gr1j6F4UJbIYCTnIWIevJa73UjIFyTuYvjfUYl19UUUUU X-CM-SenderInfo: 5olet0hnxqqx5xdzvxpfor3voofrz/1tbiAQADBWbFpP9DdQAAsJ Content-Type: text/plain; charset="utf-8" From: Baokun Li In ext4_ext_try_to_merge_up(), set path[1].p_bh to NULL after it has been released, otherwise it may be released twice. An example of what triggers this is as follows: split2 map split1 |--------|-------|--------| ext4_ext_map_blocks ext4_ext_handle_unwritten_extents ext4_split_convert_extents // path->p_depth =3D=3D 0 ext4_split_extent // 1. do split1 ext4_split_extent_at |ext4_ext_insert_extent | ext4_ext_create_new_leaf | ext4_ext_grow_indepth | le16_add_cpu(&neh->eh_depth, 1) | ext4_find_extent | // return -ENOMEM |// get error and try zeroout |path =3D ext4_find_extent | path->p_depth =3D 1 |ext4_ext_try_to_merge | ext4_ext_try_to_merge_up | path->p_depth =3D 0 | brelse(path[1].p_bh) ---> not set to NULL here |// zeroout success // 2. update path ext4_find_extent // 3. do split2 ext4_split_extent_at ext4_ext_insert_extent ext4_ext_create_new_leaf ext4_ext_grow_indepth le16_add_cpu(&neh->eh_depth, 1) ext4_find_extent path[0].p_bh =3D NULL; path->p_depth =3D 1 read_extent_tree_block ---> return err // path[1].p_bh is still the old value ext4_free_ext_path ext4_ext_drop_refs // path->p_depth =3D=3D 1 brelse(path[1].p_bh) ---> brelse a buffer twice Finally got the following WARRNING when removing the buffer from lru: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D VFS: brelse: Trying to free free buffer WARNING: CPU: 2 PID: 72 at fs/buffer.c:1241 __brelse+0x58/0x90 CPU: 2 PID: 72 Comm: kworker/u19:1 Not tainted 6.9.0-dirty #716 RIP: 0010:__brelse+0x58/0x90 Call Trace: __find_get_block+0x6e7/0x810 bdev_getblk+0x2b/0x480 __ext4_get_inode_loc+0x48a/0x1240 ext4_get_inode_loc+0xb2/0x150 ext4_reserve_inode_write+0xb7/0x230 __ext4_mark_inode_dirty+0x144/0x6a0 ext4_ext_insert_extent+0x9c8/0x3230 ext4_ext_map_blocks+0xf45/0x2dc0 ext4_map_blocks+0x724/0x1700 ext4_do_writepages+0x12d6/0x2a70 [...] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Fixes: ecb94f5fdf4b ("ext4: collapse a single extent tree block into the in= ode if possible") Cc: stable@kernel.org Signed-off-by: Baokun Li Reviewed-by: Jan Kara Reviewed-by: Ojaswin Mujoo Tested-by: Ojaswin Mujoo --- fs/ext4/extents.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c index cd2e71123a25..c4a4573440c1 100644 --- a/fs/ext4/extents.c +++ b/fs/ext4/extents.c @@ -1890,6 +1890,7 @@ static void ext4_ext_try_to_merge_up(handle_t *handle, path[0].p_hdr->eh_max =3D cpu_to_le16(max_root); =20 brelse(path[1].p_bh); + path[1].p_bh =3D NULL; ext4_free_blocks(handle, inode, NULL, blk, 1, EXT4_FREE_BLOCKS_METADATA | EXT4_FREE_BLOCKS_FORGET); } --=20 2.39.2