KCSAN: data-race in __ext4_update_other_inode_time / writeback_sb

KCSAN: data-race in __ext4_update_other_inode_time / writeback_sb_inodes (2)
Status: auto-closed as invalid on 2021/03/05 19:46
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 180d, last: 180d

similar bugs (2):
Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __ext4_update_other_inode_time / writeback_sb_inodes				1	362d	362d	0/22	auto-closed as invalid on 2020/09/03 23:58
upstream	KCSAN: data-race in __ext4_update_other_inode_time / writeback_sb_inodes (3)				1	53d	53d	0/22	auto-closed as invalid on 2021/07/09 20:34

Sample crash report:

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

write to 0xffff88810e74fcd8 of 8 bytes by task 329 on cpu 0:
 writeback_sb_inodes+0x4a1/0xff0 fs/fs-writeback.c:1712
 wb_writeback+0x27d/0x660 fs/fs-writeback.c:1896
 wb_do_writeback+0x101/0x5d0 fs/fs-writeback.c:2041
 wb_workfn+0xc8/0x430 fs/fs-writeback.c:2082
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x616/0xa70 kernel/workqueue.c:2421
 kthread+0x20b/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffff88810e74fcd8 of 8 bytes by task 8431 on cpu 1:
 __ext4_update_other_inode_time+0x45/0x550 fs/ext4/inode.c:4964
 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+0x11b6/0x16f0 fs/ext4/inode.c:5725
 __ext4_mark_inode_dirty+0x4d6/0x5e0 fs/ext4/inode.c:5919
 __ext4_unlink+0x683/0x6c0 fs/ext4/namei.c:3226
 ext4_unlink+0x1f1/0x3f0 fs/ext4/namei.c:3274
 vfs_unlink+0x232/0x3c0 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: 1 PID: 8431 Comm: syz-executor.0 Not tainted 5.11.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2021/01/29 19:40	upstream	bec4c2968fce	fc9fd31e	.config	log	report			info	KCSAN: data-race in __ext4_update_other_inode_time / writeback_sb_inodes