KCSAN: data-race in __ext4_unlink / __ext4_update_other_inode

KCSAN: data-race in __ext4_unlink / __ext4_update_other_inode_time
Status: moderation: reported on 2020/12/07 11:47
Reported-by: syzbot+2948cdc08a7001ecf1e5@syzkaller.appspotmail.com
First crash: 94d, last: 16d

Sample crash report:

==================================================================
BUG: KCSAN: data-race in __ext4_unlink / __ext4_update_other_inode_time

write to 0xffff88800f6bf240 of 8 bytes by task 24306 on cpu 1:
 __ext4_unlink+0x4c3/0x6a0 fs/ext4/namei.c:3233
 ext4_unlink+0x1f1/0x3f0 fs/ext4/namei.c:3268
 vfs_unlink+0x232/0x3b0 fs/namei.c:3835
 do_unlinkat+0x28a/0x4d0 fs/namei.c:3899
 __do_sys_unlink fs/namei.c:3945 [inline]
 __se_sys_unlink fs/namei.c:3943 [inline]
 __x64_sys_unlink+0x2c/0x30 fs/namei.c:3943
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88800f6bf240 of 8 bytes by task 8456 on cpu 0:
 ext4_encode_extra_time fs/ext4/ext4.h:891 [inline]
 __ext4_update_other_inode_time+0x14f/0x550 fs/ext4/inode.c:4979
 ext4_update_other_inodes_time fs/ext4/inode.c:5011 [inline]
 ext4_do_update_inode fs/ext4/inode.c:5140 [inline]
 ext4_mark_iloc_dirty+0x1286/0x1650 fs/ext4/inode.c:5721
 __ext4_mark_inode_dirty+0x4cd/0x5d0 fs/ext4/inode.c:5915
 __ext4_unlink+0x66e/0x6a0 fs/ext4/namei.c:3220
 ext4_unlink+0x1f1/0x3f0 fs/ext4/namei.c:3268
 vfs_unlink+0x232/0x3b0 fs/namei.c:3835
 do_unlinkat+0x28a/0x4d0 fs/namei.c:3899
 __do_sys_unlink fs/namei.c:3945 [inline]
 __se_sys_unlink fs/namei.c:3943 [inline]
 __x64_sys_unlink+0x2c/0x30 fs/namei.c:3943
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8456 Comm: syz-executor.3 Not tainted 5.11.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (9):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Maintainers
ci2-upstream-kcsan-gce	2021/01/09 03:23	upstream	6279d812	c104d4a3	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2021/01/04 09:11	upstream	e71ba945	79264ae3	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/12/30 23:20	upstream	f6e1ea19	ecb8c012	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/12/19 03:11	upstream	3644e2d2	04201c06	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/12/18 14:07	upstream	a409ed15	04201c06	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/12/14 22:36	upstream	fab0fca1	97183ed7	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/12/05 09:07	upstream	b3298500	0ef84591	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/11/18 05:18	upstream	111e91a6	09323409	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu
ci2-upstream-kcsan-gce	2020/10/23 00:24	upstream	96485e44	4e740c00	.config	log	report	info	adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, tytso@mit.edu