KCSAN: data-race in iput / writeback_sb

KCSAN: data-race in iput / writeback_sb_inodes (6)
Status: auto-closed as invalid on 2021/07/20 06:50
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 112d, last: 104d

similar bugs (5):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in iput / writeback_sb_inodes (2)	1	466d	466d	0/22	closed as invalid on 2020/06/18 14:13
upstream	KCSAN: data-race in iput / writeback_sb_inodes (3)	1	447d	447d	0/22	auto-closed as invalid on 2020/08/11 19:26
upstream	KCSAN: data-race in iput / writeback_sb_inodes	1	567d	567d	0/22	auto-closed as invalid on 2020/05/18 05:32
upstream	KCSAN: data-race in iput / writeback_sb_inodes (5)	4	242d	266d	0/22	auto-closed as invalid on 2021/03/04 09:19
upstream	KCSAN: data-race in iput / writeback_sb_inodes (4)	7	330d	294d	0/22	auto-closed as invalid on 2020/12/21 11:42

Sample crash report:

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

write to 0xffff8881065e5398 of 8 bytes by task 1924 on cpu 0:
 writeback_sb_inodes+0x3cc/0xf10 fs/fs-writeback.c:1721
 __writeback_inodes_wb fs/fs-writeback.c:1801 [inline]
 wb_writeback+0x327/0x700 fs/fs-writeback.c:1907
 wb_check_start_all fs/fs-writeback.c:2031 [inline]
 wb_do_writeback+0x330/0x510 fs/fs-writeback.c:2057
 wb_workfn+0xc8/0x520 fs/fs-writeback.c:2091
 process_one_work+0x3e9/0x8f0 kernel/workqueue.c:2276
 worker_thread+0x636/0xae0 kernel/workqueue.c:2422
 kthread+0x1d0/0x1f0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffff8881065e5398 of 8 bytes by task 1762 on cpu 1:
 iput+0x2e/0x590 fs/inode.c:1676
 dentry_unlink_inode+0x23a/0x260 fs/dcache.c:376
 d_delete+0x78/0xe0 fs/dcache.c:2505
 vfs_rmdir+0x2a6/0x2c0 fs/namei.c:3909
 do_rmdir+0x14a/0x2e0 fs/namei.c:3958
 __do_sys_rmdir fs/namei.c:3976 [inline]
 __se_sys_rmdir fs/namei.c:3974 [inline]
 __x64_sys_rmdir+0x2c/0x30 fs/namei.c:3974
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000020007 -> 0x0000000000020080

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 1762 Comm: syz-executor.5 Not tainted 5.13.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (2):
Manager	Time	Kernel	Commit	Syzkaller	Config	Log	Report	Syz repro	C repro	VM info	Title
ci2-upstream-kcsan-gce	2021/06/15 06:41	upstream	009c9aa5be65	1ba81399	.config	log	report			info	KCSAN: data-race in iput / writeback_sb_inodes
ci2-upstream-kcsan-gce	2021/06/08 02:12	upstream	614124bea77e	b718257f	.config	log	report			info	KCSAN: data-race in iput / writeback_sb_inodes