KCSAN: data-race in __d_lookup_done / __dentry

KCSAN: data-race in __d_lookup_done / __dentry_kill (3)
Status: auto-closed as invalid on 2020/11/08 00:33
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 293d, last: 293d

similar bugs (4):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __d_lookup_done / __dentry_kill (5)	5	51d	87d	0/22	auto-closed as invalid on 2021/07/08 04:16
upstream	KCSAN: data-race in __d_lookup_done / __dentry_kill (4)	3	172d	196d	0/22	auto-closed as invalid on 2021/03/09 07:41
upstream	KCSAN: data-race in __d_lookup_done / __dentry_kill (2)	4	375d	395d	0/22	auto-closed as invalid on 2020/08/18 04:12
upstream	KCSAN: data-race in __d_lookup_done / __dentry_kill	29	461d	635d	0/22	auto-closed as invalid on 2020/06/18 14:14

Sample crash report:

==================================================================
BUG: KCSAN: data-race in __d_lookup_done / __dentry_kill

write to 0xffff8880a4f336c0 of 4 bytes by task 5076 on cpu 1:
 __d_lookup_done+0x8e/0x240 fs/dcache.c:2648
 d_lookup_done include/linux/dcache.h:369 [inline]
 __lookup_slow+0x206/0x250 fs/namei.c:1545
 lookup_slow fs/namei.c:1561 [inline]
 walk_component+0x2a5/0x350 fs/namei.c:1860
 link_path_walk+0x462/0x730 fs/namei.c:2179
 path_lookupat+0x7b/0x560 fs/namei.c:2332
 filename_lookup+0xf2/0x380 fs/namei.c:2366
 user_path_at_empty+0x3b/0x50 fs/namei.c:2646
 user_path_at include/linux/namei.h:59 [inline]
 do_faccessat+0x260/0x500 fs/open.c:423
 __do_sys_access fs/open.c:482 [inline]
 __se_sys_access fs/open.c:480 [inline]
 __x64_sys_access+0x33/0x40 fs/open.c:480
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880a4f336c0 of 4 bytes by task 25409 on cpu 0:
 dentry_unlist fs/dcache.c:544 [inline]
 __dentry_kill+0x1ef/0x450 fs/dcache.c:575
 dentry_kill fs/dcache.c:692 [inline]
 dput+0x208/0x420 fs/dcache.c:878
 handle_mounts fs/namei.c:1389 [inline]
 step_into+0x448/0xe70 fs/namei.c:1690
 walk_component+0x190/0x350 fs/namei.c:1866
 link_path_walk+0x462/0x730 fs/namei.c:2179
 path_lookupat+0x7b/0x560 fs/namei.c:2332
 filename_lookup+0xf2/0x380 fs/namei.c:2366
 user_path_at_empty+0x3b/0x50 fs/namei.c:2646
 user_path_at include/linux/namei.h:59 [inline]
 do_faccessat+0x260/0x500 fs/open.c:423
 __do_sys_access fs/open.c:482 [inline]
 __se_sys_access fs/open.c:480 [inline]
 __x64_sys_access+0x33/0x40 fs/open.c:480
 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: 25409 Comm: systemd-rfkill Not tainted 5.9.0-rc7-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	2020/10/04 00:32	upstream	22fbc037cd32	1a3f9408	.config	log	report			info