syzbot

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BUG: KCSAN: data-race in fill_mg_cmtime / shmem_symlink

write to 0xffff8881038e966c of 4 bytes by task 18226 on cpu 1:
 inode_set_mtime_to_ts include/linux/fs.h:1660 [inline]
 shmem_symlink+0x387/0x3b0 mm/shmem.c:4130
 vfs_symlink+0x106/0x220 fs/namei.c:5643
 filename_symlinkat+0xe8/0x2b0 fs/namei.c:5668
 __do_sys_symlink fs/namei.c:5695 [inline]
 __se_sys_symlink+0x42/0x1b0 fs/namei.c:5691
 __x64_sys_symlink+0x31/0x40 fs/namei.c:5691
 x64_sys_call+0x2465/0x3020 arch/x86/include/generated/asm/syscalls_64.h:89
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881038e966c of 4 bytes by task 16195 on cpu 0:
 inode_get_mtime_nsec include/linux/fs.h:1646 [inline]
 inode_get_mtime include/linux/fs.h:1652 [inline]
 fill_mg_cmtime+0x5b/0x240 fs/stat.c:55
 generic_fillattr+0x24a/0x340 fs/stat.c:99
 shmem_getattr+0x181/0x200 mm/shmem.c:1302
 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+0x118/0x170 fs/stat.c:373
 __do_sys_newfstatat fs/stat.c:538 [inline]
 __se_sys_newfstatat+0x55/0x3e0 fs/stat.c:532
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:532
 x64_sys_call+0x2c64/0x3020 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x2d9cadca -> 0x2de0b43a

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 16195 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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