syzbot

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BUG: KCSAN: data-race in __d_instantiate / lookup_fast

read-write to 0xffff888105714780 of 4 bytes by task 3441 on cpu 0:
 __d_instantiate+0x2d5/0x3c0 fs/dcache.c:1879
 d_instantiate+0x59/0x80 fs/dcache.c:1904
 shmem_symlink+0x36a/0x3a0 mm/shmem.c:3966
 vfs_symlink+0xca/0x1d0 fs/namei.c:4669
 do_symlinkat+0xdf/0x350 fs/namei.c:4695
 __do_sys_symlink fs/namei.c:4716 [inline]
 __se_sys_symlink fs/namei.c:4714 [inline]
 __x64_sys_symlink+0x50/0x60 fs/namei.c:4714
 x64_sys_call+0x28b0/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:89
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888105714780 of 4 bytes by task 3288 on cpu 1:
 d_revalidate fs/namei.c:926 [inline]
 lookup_fast+0xd9/0x2a0 fs/namei.c:1740
 walk_component+0x3f/0x230 fs/namei.c:2108
 lookup_last fs/namei.c:2610 [inline]
 path_lookupat+0x10a/0x2b0 fs/namei.c:2634
 filename_lookup+0x150/0x340 fs/namei.c:2663
 vfs_statx+0x9a/0x170 fs/stat.c:344
 vfs_fstatat fs/stat.c:366 [inline]
 __do_sys_newfstatat fs/stat.c:530 [inline]
 __se_sys_newfstatat+0xdc/0x300 fs/stat.c:524
 __x64_sys_newfstatat+0x55/0x70 fs/stat.c:524
 x64_sys_call+0x236d/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:263
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000008 -> 0x00600008

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3288 Comm: udevd Tainted: G        W          6.13.0-rc6-syzkaller #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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