syzbot

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BUG: KCSAN: data-race in fill_mg_cmtime / simple_unlink

write to 0xffff8881039cef74 of 4 bytes by task 18816 on cpu 1:
 inode_set_mtime_to_ts include/linux/fs.h:1658 [inline]
 __simple_unlink fs/libfs.c:790 [inline]
 simple_unlink+0x54/0x80 fs/libfs.c:806
 shmem_unlink+0x12d/0x140 mm/shmem.c:3991
 shmem_rename2+0x18e/0x310 mm/shmem.c:4072
 vfs_rename+0x97f/0xad0 fs/namei.c:5938
 do_renameat2+0x39a/0x850 fs/namei.c:6056
 __do_sys_rename fs/namei.c:6099 [inline]
 __se_sys_rename fs/namei.c:6097 [inline]
 __x64_sys_rename+0x58/0x70 fs/namei.c:6097
 x64_sys_call+0x24e/0x3000 arch/x86/include/generated/asm/syscalls_64.h:83
 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 0xffff8881039cef74 of 4 bytes by task 20131 on cpu 0:
 inode_get_mtime_nsec include/linux/fs.h:1644 [inline]
 inode_get_mtime include/linux/fs.h:1650 [inline]
 fill_mg_cmtime+0x5b/0x260 fs/stat.c:55
 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 fs/stat.c:262 [inline]
 vfs_statx_path fs/stat.c:299 [inline]
 vfs_statx+0x113/0x3b0 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: 0x350c6241 -> 0x359972b8

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 20131 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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