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 31198C433F5 for ; Wed, 27 Apr 2022 12:31:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234265AbiD0MfG (ORCPT ); Wed, 27 Apr 2022 08:35:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52412 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234278AbiD0MfF (ORCPT ); Wed, 27 Apr 2022 08:35:05 -0400 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AA4DE4B1F7; Wed, 27 Apr 2022 05:31:51 -0700 (PDT) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 25822210E1; Wed, 27 Apr 2022 12:31:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1651062710; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=C3N+181NGxO23xtLtvgHl8EcRvfl2YIztgq+N5zcc0Q=; b=kWUZDuXbv8n2l/4bg7OILM4Wfr0TQMfM5n6UhSLLBFO7QYMTHTlbH+FN7XNsg/mci/2Rx7 I2lkStWKbWmrJEWTtKeJ3rmPz4ywrN5IbbBdWTo7xlqxFERARNsiPV213biZtVVk/prgZw LBdLLHuyIdfvp1EFx7JNWnosE4JstNo= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1651062710; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=C3N+181NGxO23xtLtvgHl8EcRvfl2YIztgq+N5zcc0Q=; b=YDFmMRH5H6YmEcStLmEwyHz/6yKosU9Gn1KxGeR6GXSKAKCWA/0JT4zdiRl/XcfLXUj4ki wXIOqfgdtdVLYTBQ== Received: from quack3.suse.cz (unknown [10.100.224.230]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 0C0EB2C141; Wed, 27 Apr 2022 12:31:49 +0000 (UTC) Received: by quack3.suse.cz (Postfix, from userid 1000) id 95379A0620; Wed, 27 Apr 2022 14:31:46 +0200 (CEST) Date: Wed, 27 Apr 2022 14:31:46 +0200 From: Jan Kara To: Baokun Li Cc: linux-ext4@vger.kernel.org, tytso@mit.edu, adilger.kernel@dilger.ca, jack@suse.cz, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, yebin10@huawei.com, yukuai3@huawei.com, stable@vger.kernel.org, Hulk Robot Subject: Re: [PATCH v2] ext4: fix race condition between ext4_write and ext4_convert_inline_data Message-ID: <20220427123146.ymm7lodedvtot2ij@quack3.lan> References: <20220426140658.1046700-1-libaokun1@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220426140658.1046700-1-libaokun1@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org On Tue 26-04-22 22:06:58, Baokun Li wrote: > Hulk Robot reported a BUG_ON: > ================================================================== > EXT4-fs error (device loop3): ext4_mb_generate_buddy:805: group 0, > block bitmap and bg descriptor inconsistent: 25 vs 31513 free clusters > kernel BUG at fs/ext4/ext4_jbd2.c:53! > invalid opcode: 0000 [#1] SMP KASAN PTI > CPU: 0 PID: 25371 Comm: syz-executor.3 Not tainted 5.10.0+ #1 > RIP: 0010:ext4_put_nojournal fs/ext4/ext4_jbd2.c:53 [inline] > RIP: 0010:__ext4_journal_stop+0x10e/0x110 fs/ext4/ext4_jbd2.c:116 > [...] > Call Trace: > ext4_write_inline_data_end+0x59a/0x730 fs/ext4/inline.c:795 > generic_perform_write+0x279/0x3c0 mm/filemap.c:3344 > ext4_buffered_write_iter+0x2e3/0x3d0 fs/ext4/file.c:270 > ext4_file_write_iter+0x30a/0x11c0 fs/ext4/file.c:520 > do_iter_readv_writev+0x339/0x3c0 fs/read_write.c:732 > do_iter_write+0x107/0x430 fs/read_write.c:861 > vfs_writev fs/read_write.c:934 [inline] > do_pwritev+0x1e5/0x380 fs/read_write.c:1031 > [...] > ================================================================== > > Above issue may happen as follows: > cpu1 cpu2 > __________________________|__________________________ > do_pwritev > vfs_writev > do_iter_write > ext4_file_write_iter > ext4_buffered_write_iter > generic_perform_write > ext4_da_write_begin > vfs_fallocate > ext4_fallocate > ext4_convert_inline_data > ext4_convert_inline_data_nolock > ext4_destroy_inline_data_nolock > clear EXT4_STATE_MAY_INLINE_DATA > ext4_map_blocks > ext4_ext_map_blocks > ext4_mb_new_blocks > ext4_mb_regular_allocator > ext4_mb_good_group_nolock > ext4_mb_init_group > ext4_mb_init_cache > ext4_mb_generate_buddy --> error > ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) > ext4_restore_inline_data > set EXT4_STATE_MAY_INLINE_DATA > ext4_block_write_begin > ext4_da_write_end > ext4_test_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA) > ext4_write_inline_data_end > handle=NULL > ext4_journal_stop(handle) > __ext4_journal_stop > ext4_put_nojournal(handle) > ref_cnt = (unsigned long)handle > BUG_ON(ref_cnt == 0) ---> BUG_ON > > The lock held by ext4_convert_inline_data is xattr_sem, but the lock > held by generic_perform_write is i_rwsem. Therefore, the two locks can > be concurrent. To solve above issue, we just add inode_lock in > ext4_convert_inline_data. > > Fixes: 0c8d414f163f ("ext4: let fallocate handle inline data correctly") > Cc: stable@vger.kernel.org > Reported-by: Hulk Robot > Signed-off-by: Baokun Li Thanks for the report and the patch. I agree inode_lock is needed to protect the conversion. However you cannot lock it inside ext4_convert_inline_data() because it is often called with inode_lock already held (in fact in most of the other cases as far as I have checked). So the right fix is to reorganize ext4_fallocate() a bit to do something like: ext4_clear_inode_state(inode, EXT4_STATE_MAY_INLINE_DATA); if (ext4_has_inline_data(inode)) { inode_lock(inode); ret = ext4_convert_inline_data(inode); inode_unlock(inode); if (ret) goto exit; } and remove similar handling from ext4_punch_hole() (and make sure it uses the new handling in ext4_fallocate()). Honza -- Jan Kara SUSE Labs, CR