syzbot

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BUG: KCSAN: data-race in fill_mg_cmtime / shmem_symlink

write to 0xffff888107431834 of 4 bytes by task 3306 on cpu 1:
 inode_set_mtime_to_ts include/linux/fs.h:1658 [inline]
 shmem_symlink+0x387/0x3b0 mm/shmem.c:4144
 vfs_symlink+0x1b4/0x1f0 fs/namei.c:5514
 do_symlinkat+0xf0/0x470 fs/namei.c:5541
 __do_sys_symlink fs/namei.c:5567 [inline]
 __se_sys_symlink fs/namei.c:5565 [inline]
 __x64_sys_symlink+0x50/0x60 fs/namei.c:5565
 x64_sys_call+0x24a9/0x3000 arch/x86/include/generated/asm/syscalls_64.h:89
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888107431834 of 4 bytes by task 3305 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+0x113/0x390 fs/stat.c:356
 vfs_fstatat+0x115/0x170 fs/stat.c:375
 __do_sys_newfstatat fs/stat.c:542 [inline]
 __se_sys_newfstatat+0x55/0x260 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+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x29717af1 -> 0x2a20bb6a

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3305 Comm: udevd Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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