KCSAN: data-race in d_set_mounted / link_path

KCSAN: data-race in d_set_mounted / link_path_walk (4)
Status: auto-closed as invalid on 2021/06/12 19:25
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 99d, last: 76d

similar bugs (3):
Kernel	Title	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in d_set_mounted / link_path_walk (2)	1	202d	202d	0/22	auto-closed as invalid on 2021/02/07 03:59
upstream	KCSAN: data-race in d_set_mounted / link_path_walk (3)	1	140d	140d	0/22	auto-closed as invalid on 2021/04/10 08:08
upstream	KCSAN: data-race in d_set_mounted / link_path_walk	1	323d	323d	0/22	auto-closed as invalid on 2020/10/09 14:20

Sample crash report:

==================================================================
BUG: KCSAN: data-race in d_set_mounted / link_path_walk

write to 0xffff88813131ecc0 of 4 bytes by task 31124 on cpu 1:
 d_set_mounted+0x117/0x200 fs/dcache.c:1494
 get_mountpoint+0x1c0/0x350 fs/namespace.c:755
 lock_mount+0x86/0x1d0 fs/namespace.c:2226
 do_new_mount_fc fs/namespace.c:2848 [inline]
 do_new_mount fs/namespace.c:2907 [inline]
 path_mount+0x1948/0x1ce0 fs/namespace.c:3235
 do_mount fs/namespace.c:3248 [inline]
 __do_sys_mount fs/namespace.c:3456 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3433
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3433
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88813131ecc0 of 4 bytes by task 31125 on cpu 0:
 link_path_walk+0x37d/0x780 fs/namei.c:2231
 path_openat+0x1a0/0x20b0 fs/namei.c:3490
 do_filp_open+0xd9/0x1f0 fs/namei.c:3521
 do_sys_openat2+0xa3/0x250 fs/open.c:1187
 do_sys_open fs/open.c:1203 [inline]
 __do_sys_creat fs/open.c:1277 [inline]
 __se_sys_creat fs/open.c:1271 [inline]
 __x64_sys_creat+0x62/0x80 fs/open.c:1271
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 31125 Comm: syz-executor.3 Not tainted 5.12.0-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	2021/05/08 19:17	upstream	dd860052c99b	bc5434be	.config	log	report			info	KCSAN: data-race in d_set_mounted / link_path_walk
ci2-upstream-kcsan-gce	2021/04/15 22:10	upstream	7f75285ca572	c59079a6	.config	log	report			info	KCSAN: data-race in d_set_mounted / link_path_walk