syzbot

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BUG: KCSAN: data-race in __d_instantiate / path_lookupat

read-write to 0xffff888107a06cc0 of 4 bytes by task 3310 on cpu 0:
 fsnotify_update_flags include/linux/fsnotify_backend.h:-1 [inline]
 __d_instantiate+0x2a8/0x390 fs/dcache.c:1977
 d_make_persistent+0x78/0x110 fs/dcache.c:2793
 shmem_symlink+0x3a4/0x3b0 mm/shmem.c:4146
 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+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888107a06cc0 of 4 bytes by task 3006 on cpu 1:
 d_managed include/linux/dcache.h:403 [inline]
 step_into fs/namei.c:2078 [inline]
 walk_component fs/namei.c:2227 [inline]
 lookup_last fs/namei.c:2722 [inline]
 path_lookupat+0x1d8/0x500 fs/namei.c:2746
 filename_lookup+0x147/0x340 fs/namei.c:2775
 do_readlinkat+0x7d/0x320 fs/stat.c:576
 __do_sys_readlink fs/stat.c:613 [inline]
 __se_sys_readlink fs/stat.c:610 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:610
 x64_sys_call+0x2af1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000080 -> 0x08300080

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3006 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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