KCSAN: data-race in fill_mg_cmtime / inode_set_ctime

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in fill_mg_cmtime / inode_set_ctime_current fs	6				2	71d	95d	0/29	auto-obsoleted due to no activity on 2026/01/14 01:59

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BUG: KCSAN: data-race in fill_mg_cmtime / inode_set_ctime_current

write to 0xffff8881039e7250 of 8 bytes by task 3305 on cpu 0:
 inode_set_ctime_current+0x592/0x810 fs/inode.c:2843
 shmem_mknod+0x127/0x170 mm/shmem.c:3889
 shmem_create+0x34/0x50 mm/shmem.c:3943
 lookup_open fs/namei.c:4449 [inline]
 open_last_lookups fs/namei.c:4549 [inline]
 path_openat+0x1121/0x23c0 fs/namei.c:4793
 do_filp_open+0x15d/0x280 fs/namei.c:4823
 do_sys_openat2+0xa6/0x150 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1447
 x64_sys_call+0x2b07/0x3000 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881039e7250 of 8 bytes by task 3306 on cpu 1:
 fill_mg_cmtime+0x86/0x260 fs/stat.c:56
 generic_fillattr+0x24a/0x340 fs/stat.c:99
 shmem_getattr+0x181/0x200 mm/shmem.c:1274
 vfs_getattr_nosec+0x146/0x1e0 fs/stat.c:213
 vfs_getattr+0x48/0x60 fs/stat.c:262
 vfs_statx_path+0x28/0x140 fs/stat.c:299
 vfs_statx+0xc4/0x170 fs/stat.c:356
 vfs_fstatat+0x115/0x170 fs/stat.c:375
 __do_sys_newfstatat fs/stat.c:542 [inline]
 __se_sys_newfstatat+0x55/0x3e0 fs/stat.c:536
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:536
 x64_sys_call+0x111f/0x3000 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000773d97c1 -> 0x00000000773d97c2

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3306 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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