syzbot

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BUG: KCSAN: data-race in fill_mg_cmtime / shmem_unlink

write to 0xffff88810356782c of 4 bytes by task 3509 on cpu 1:
 inode_set_mtime_to_ts include/linux/fs.h:1831 [inline]
 shmem_unlink+0x13c/0x170 mm/shmem.c:4038
 shmem_rename2+0x1a1/0x290 mm/shmem.c:4127
 vfs_rename+0x7e8/0xa30 fs/namei.c:5216
 do_renameat2+0x52a/0x9e0 fs/namei.c:5364
 __do_sys_rename fs/namei.c:5411 [inline]
 __se_sys_rename fs/namei.c:5409 [inline]
 __x64_sys_rename+0x58/0x70 fs/namei.c:5409
 x64_sys_call+0x1f9/0x3000 arch/x86/include/generated/asm/syscalls_64.h:83
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810356782c of 4 bytes by task 3294 on cpu 0:
 inode_get_mtime_nsec include/linux/fs.h:1817 [inline]
 inode_get_mtime include/linux/fs.h:1823 [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:1294
 vfs_getattr_nosec+0x143/0x1e0 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+0x135a/0x3000 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x3b8e954c -> 0x3b9255b1

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3294 Comm: udevd Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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