KCSAN: data-race in __d_lookup_rcu_op_compare / __d

Kernel	Title	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __d_lookup_rcu_op_compare / __d_rehash (2) fs				3	179d	202d	0/28	auto-obsoleted due to no activity on 2025/01/13 18:14
upstream	KCSAN: data-race in __d_lookup_rcu_op_compare / __d_rehash fs				1	274d	274d	0/28	auto-obsoleted due to no activity on 2024/09/19 20:54

==================================================================
BUG: KCSAN: data-race in __d_lookup_rcu_op_compare / __d_rehash

read to 0xffff8881068ff850 of 8 bytes by task 11176 on cpu 1:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:359 [inline]
 __d_lookup_rcu_op_compare+0x104/0x270 fs/dcache.c:2183
 __d_lookup_rcu+0x28e/0x2a0 fs/dcache.c:2246
 d_alloc_parallel+0x209/0xc40 fs/dcache.c:2536
 lookup_open fs/namei.c:3623 [inline]
 open_last_lookups fs/namei.c:3800 [inline]
 path_openat+0x6b5/0x2170 fs/namei.c:4036
 do_filp_open+0x109/0x230 fs/namei.c:4066
 do_sys_openat2+0xa6/0x110 fs/open.c:1429
 do_sys_open fs/open.c:1444 [inline]
 __do_sys_openat fs/open.c:1460 [inline]
 __se_sys_openat fs/open.c:1455 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1455
 x64_sys_call+0x1af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff8881068ff850 of 8 bytes by task 11174 on cpu 0:
 hlist_bl_add_head_rcu include/linux/rculist_bl.h:81 [inline]
 __d_rehash+0x9e/0x1f0 fs/dcache.c:2465
 __d_add+0x364/0x4c0 fs/dcache.c:2681
 d_splice_alias+0xd6/0x280 fs/dcache.c:3025
 proc_sys_lookup+0x1f6/0x320 fs/proc/proc_sysctl.c:545
 lookup_open fs/namei.c:3679 [inline]
 open_last_lookups fs/namei.c:3800 [inline]
 path_openat+0xcf0/0x2170 fs/namei.c:4036
 do_filp_open+0x109/0x230 fs/namei.c:4066
 do_sys_openat2+0xa6/0x110 fs/open.c:1429
 do_sys_open fs/open.c:1444 [inline]
 __do_sys_openat fs/open.c:1460 [inline]
 __se_sys_openat fs/open.c:1455 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1455
 x64_sys_call+0x1af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 11174 Comm: syz-executor Not tainted 6.15.0-rc4-syzkaller-00011-gf15d97df5afa #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================

Time	Kernel	Commit	Syzkaller	Config	Log	Report	VM info	Assets (help?)	Manager	Title
2025/04/28 19:20	upstream	f15d97df5afa	aeb6ec69	.config	console log	report	info	[disk image] [vmlinux] [kernel image]	ci2-upstream-kcsan-gce	KCSAN: data-race in __d_lookup_rcu_op_compare / __d_rehash
2025/03/21 20:59	upstream	d07de43e3f05	c6512ef7	.config	console log	report	info	[disk image] [vmlinux] [kernel image]	ci2-upstream-kcsan-gce	KCSAN: data-race in __d_lookup_rcu_op_compare / __d_rehash
2025/03/12 16:06	upstream	0fed89a961ea	ee70e6db	.config	console log	report	info	[disk image] [vmlinux] [kernel image]	ci2-upstream-kcsan-gce	KCSAN: data-race in __d_lookup_rcu_op_compare / __d_rehash
2025/02/28 08:03	upstream	1e15510b71c9	6a8fcbc4	.config	console log	report	info	[disk image] [vmlinux] [kernel image]	ci2-upstream-kcsan-gce	KCSAN: data-race in __d_lookup_rcu_op_compare / __d_rehash
2025/02/10 04:54	upstream	69b54314c975	ef44b750	.config	console log	report	info	[disk image] [vmlinux] [kernel image]	ci2-upstream-kcsan-gce	KCSAN: data-race in __d_lookup_rcu_op_compare / __d_rehash