syzbot

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BUG: KCSAN: data-race in fill_mg_cmtime / shmem_symlink

write to 0xffff888105304f7c of 4 bytes by task 3570 on cpu 1:
 inode_set_mtime_to_ts include/linux/fs.h:1658 [inline]
 shmem_symlink+0x387/0x3b0 mm/shmem.c:4140
 vfs_symlink+0x2c3/0x3c0 fs/namei.c:5523
 do_symlinkat+0xf0/0x460 fs/namei.c:5550
 __do_sys_symlink fs/namei.c:5576 [inline]
 __se_sys_symlink fs/namei.c:5574 [inline]
 __x64_sys_symlink+0x50/0x60 fs/namei.c:5574
 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+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888105304f7c of 4 bytes by task 7585 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+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: 0x352324a3 -> 0x3abc4476

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 7585 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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