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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 E1CC9C4BA24 for ; Thu, 27 Feb 2020 08:18:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ABCA82467F for ; Thu, 27 Feb 2020 08:18:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582791523; bh=MFSTL8vFxyGLFY1x3k+C5tq5OXO1ZIoG0cT42Bu/2mU=; h=Subject:To:Cc:From:Date:List-ID:From; b=1VioR7P+9MP8GBngXnaq3WOKQNwKnOPsxIkUO5//C3sRo54BJUB7ZUvComNKje6N9 g3YznkCfZWVDGt8ZXRYgC0fuPQ7myDDvo7LIg2JHLxHbLrpIj8dRHHqhDOjQzcRmbJ 4pLHlyDkSgRaq7lTNxvRNoTJni5FVoRj9rP5Y2FQ= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728480AbgB0ISn (ORCPT ); Thu, 27 Feb 2020 03:18:43 -0500 Received: from out2-smtp.messagingengine.com ([66.111.4.26]:55961 "EHLO out2-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726999AbgB0ISn (ORCPT ); Thu, 27 Feb 2020 03:18:43 -0500 Received: from compute1.internal (compute1.nyi.internal [10.202.2.41]) by mailout.nyi.internal (Postfix) with ESMTP id 0E86521FC6; Thu, 27 Feb 2020 03:18:42 -0500 (EST) Received: from mailfrontend2 ([10.202.2.163]) by compute1.internal (MEProxy); Thu, 27 Feb 2020 03:18:42 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=TQbl7w wx5Lhp7sVfz1ZhtwT8/yzsk9C2mtetAFO28Gs=; b=N/+uTsQeNQN9dhG+ItDpTF iOFXKyrUM8FllLm0Ux3D28CBpJ1cP/sloUk6wBOR5rBarirK7lrhTM8JTIbyOYb7 asLyJc6L+3jb3rRICkwMmdDpX72skLReodeiYMFZOimF+zQvqhhsD3cLetFW5fNt oGq48PkUBWXuOGq8TQesKXDiIPHbgmH1KBWU6Y3+lHdnFJ6bRo3uxF3J9u+A/5U7 Mp52lbCc0gZpizieQPc34mClpge+0GXJueaM7iBAOWFDIJJokPSUqzZQN+omVAD9 AjgBUBcButecoAg5hSuuNKl0BUN2hhbUEmJ9AktX795b2TCFCRspCy+wxXhDyE3g == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedugedrleehgdduvddvucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucgoufhushhpvggtthffohhmrghinhculdegledmne cujfgurhepuffvhfffkfggtgfgsehtkeertddttdflnecuhfhrohhmpeeoghhrvghgkhhh sehlihhnuhigfhhouhhnuggrthhiohhnrdhorhhgqeenucffohhmrghinheprghpphhsph hothdrtghomhdpkhgvrhhnvghlrdhorhhgnecukfhppeekfedrkeeirdekledruddtjeen ucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpehgrhgvgh eskhhrohgrhhdrtghomh X-ME-Proxy: Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) by mail.messagingengine.com (Postfix) with ESMTPA id 9E36430610DB; Thu, 27 Feb 2020 03:18:41 -0500 (EST) Subject: FAILED: patch "[PATCH] ext4: fix race between writepages and enabling" failed to apply to 4.4-stable tree To: ebiggers@google.com, jack@suse.cz, tytso@mit.edu Cc: From: Date: Thu, 27 Feb 2020 09:18:40 +0100 Message-ID: <158279152018157@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From cb85f4d23f794e24127f3e562cb3b54b0803f456 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Wed, 19 Feb 2020 10:30:47 -0800 Subject: [PATCH] ext4: fix race between writepages and enabling EXT4_EXTENTS_FL If EXT4_EXTENTS_FL is set on an inode while ext4_writepages() is running on it, the following warning in ext4_add_complete_io() can be hit: WARNING: CPU: 1 PID: 0 at fs/ext4/page-io.c:234 ext4_put_io_end_defer+0xf0/0x120 Here's a minimal reproducer (not 100% reliable) (root isn't required): while true; do sync done & while true; do rm -f file touch file chattr -e file echo X >> file chattr +e file done The problem is that in ext4_writepages(), ext4_should_dioread_nolock() (which only returns true on extent-based files) is checked once to set the number of reserved journal credits, and also again later to select the flags for ext4_map_blocks() and copy the reserved journal handle to ext4_io_end::handle. But if EXT4_EXTENTS_FL is being concurrently set, the first check can see dioread_nolock disabled while the later one can see it enabled, causing the reserved handle to unexpectedly be NULL. Since changing EXT4_EXTENTS_FL is uncommon, and there may be other races related to doing so as well, fix this by synchronizing changing EXT4_EXTENTS_FL with ext4_writepages() via the existing s_writepages_rwsem (previously called s_journal_flag_rwsem). This was originally reported by syzbot without a reproducer at https://syzkaller.appspot.com/bug?extid=2202a584a00fffd19fbf, but now that dioread_nolock is the default I also started seeing this when running syzkaller locally. Link: https://lore.kernel.org/r/20200219183047.47417-3-ebiggers@kernel.org Reported-by: syzbot+2202a584a00fffd19fbf@syzkaller.appspotmail.com Fixes: 6b523df4fb5a ("ext4: use transaction reservation for extent conversion in ext4_end_io") Signed-off-by: Eric Biggers Signed-off-by: Theodore Ts'o Reviewed-by: Jan Kara Cc: stable@kernel.org diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h index 4b986ad42b9d..61b37a052052 100644 --- a/fs/ext4/ext4.h +++ b/fs/ext4/ext4.h @@ -1552,7 +1552,10 @@ struct ext4_sb_info { struct ratelimit_state s_warning_ratelimit_state; struct ratelimit_state s_msg_ratelimit_state; - /* Barrier between changing inodes' journal flags and writepages ops. */ + /* + * Barrier between writepages ops and changing any inode's JOURNAL_DATA + * or EXTENTS flag. + */ struct percpu_rw_semaphore s_writepages_rwsem; struct dax_device *s_daxdev; #ifdef CONFIG_EXT4_DEBUG diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c index 89725fa42573..fb6520f37135 100644 --- a/fs/ext4/migrate.c +++ b/fs/ext4/migrate.c @@ -407,6 +407,7 @@ static int free_ext_block(handle_t *handle, struct inode *inode) int ext4_ext_migrate(struct inode *inode) { + struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); handle_t *handle; int retval = 0, i; __le32 *i_data; @@ -431,6 +432,8 @@ int ext4_ext_migrate(struct inode *inode) */ return retval; + percpu_down_write(&sbi->s_writepages_rwsem); + /* * Worst case we can touch the allocation bitmaps, a bgd * block, and a block to link in the orphan list. We do need @@ -441,7 +444,7 @@ int ext4_ext_migrate(struct inode *inode) if (IS_ERR(handle)) { retval = PTR_ERR(handle); - return retval; + goto out_unlock; } goal = (((inode->i_ino - 1) / EXT4_INODES_PER_GROUP(inode->i_sb)) * EXT4_INODES_PER_GROUP(inode->i_sb)) + 1; @@ -452,7 +455,7 @@ int ext4_ext_migrate(struct inode *inode) if (IS_ERR(tmp_inode)) { retval = PTR_ERR(tmp_inode); ext4_journal_stop(handle); - return retval; + goto out_unlock; } i_size_write(tmp_inode, i_size_read(inode)); /* @@ -494,7 +497,7 @@ int ext4_ext_migrate(struct inode *inode) */ ext4_orphan_del(NULL, tmp_inode); retval = PTR_ERR(handle); - goto out; + goto out_tmp_inode; } ei = EXT4_I(inode); @@ -576,10 +579,11 @@ int ext4_ext_migrate(struct inode *inode) ext4_ext_tree_init(handle, tmp_inode); out_stop: ext4_journal_stop(handle); -out: +out_tmp_inode: unlock_new_inode(tmp_inode); iput(tmp_inode); - +out_unlock: + percpu_up_write(&sbi->s_writepages_rwsem); return retval; } @@ -589,7 +593,8 @@ int ext4_ext_migrate(struct inode *inode) int ext4_ind_migrate(struct inode *inode) { struct ext4_extent_header *eh; - struct ext4_super_block *es = EXT4_SB(inode->i_sb)->s_es; + struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb); + struct ext4_super_block *es = sbi->s_es; struct ext4_inode_info *ei = EXT4_I(inode); struct ext4_extent *ex; unsigned int i, len; @@ -613,9 +618,13 @@ int ext4_ind_migrate(struct inode *inode) if (test_opt(inode->i_sb, DELALLOC)) ext4_alloc_da_blocks(inode); + percpu_down_write(&sbi->s_writepages_rwsem); + handle = ext4_journal_start(inode, EXT4_HT_MIGRATE, 1); - if (IS_ERR(handle)) - return PTR_ERR(handle); + if (IS_ERR(handle)) { + ret = PTR_ERR(handle); + goto out_unlock; + } down_write(&EXT4_I(inode)->i_data_sem); ret = ext4_ext_check_inode(inode); @@ -650,5 +659,7 @@ int ext4_ind_migrate(struct inode *inode) errout: ext4_journal_stop(handle); up_write(&EXT4_I(inode)->i_data_sem); +out_unlock: + percpu_up_write(&sbi->s_writepages_rwsem); return ret; }