syzbot

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BUG: KCSAN: data-race in __d_instantiate / link_path_walk

read-write to 0xffff88811afd2240 of 4 bytes by task 15879 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:4142
 vfs_symlink+0x1b4/0x1f0 fs/namei.c:5523
 do_symlinkat+0xf0/0x460 fs/namei.c:5550
 __do_sys_symlinkat fs/namei.c:5571 [inline]
 __se_sys_symlinkat fs/namei.c:5568 [inline]
 __x64_sys_symlinkat+0x5a/0x70 fs/namei.c:5568
 x64_sys_call+0x2a36/0x3000 arch/x86/include/generated/asm/syscalls_64.h:267
 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 0xffff88811afd2240 of 4 bytes by task 15897 on cpu 1:
 d_managed include/linux/dcache.h:403 [inline]
 step_into fs/namei.c:2086 [inline]
 walk_component fs/namei.c:2235 [inline]
 link_path_walk+0x629/0xe30 fs/namei.c:2597
 path_lookupat+0x8c/0x500 fs/namei.c:2753
 filename_lookup+0x190/0x390 fs/namei.c:2783
 user_path_at+0x3e/0x130 fs/namei.c:3576
 __do_sys_chroot fs/open.c:601 [inline]
 __se_sys_chroot+0x47/0x250 fs/open.c:595
 __x64_sys_chroot+0x1f/0x30 fs/open.c:595
 x64_sys_call+0x2238/0x3000 arch/x86/include/generated/asm/syscalls_64.h:162
 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: 0x00000080 -> 0x08300080

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 15897 Comm: syz.3.2482 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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