syzbot

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BUG: KCSAN: data-race in __d_instantiate / step_into

write to 0xffff888106debdb0 of 8 bytes by task 4022 on cpu 0:
 __d_set_inode_and_type fs/dcache.c:406 [inline]
 __d_instantiate+0x1f8/0x3b0 fs/dcache.c:1936
 d_instantiate+0x59/0x80 fs/dcache.c:1963
 shmem_symlink+0x3a7/0x3d0 mm/shmem.c:4136
 vfs_symlink+0xd4/0x1e0 fs/namei.c:4817
 do_symlinkat+0xc7/0x3c0 fs/namei.c:4843
 __do_sys_symlink fs/namei.c:4864 [inline]
 __se_sys_symlink fs/namei.c:4862 [inline]
 __x64_sys_symlink+0x50/0x60 fs/namei.c:4862
 x64_sys_call+0x23d0/0x3000 arch/x86/include/generated/asm/syscalls_64.h:89
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888106debdb0 of 8 bytes by task 3001 on cpu 1:
 step_into+0x122/0x7f0 fs/namei.c:1993
 walk_component+0x162/0x220 fs/namei.c:2157
 lookup_last fs/namei.c:2652 [inline]
 path_lookupat+0xfe/0x2a0 fs/namei.c:2676
 filename_lookup+0x147/0x340 fs/namei.c:2705
 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+0x28de/0x3000 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff88811b8c37b8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3001 Comm: udevd Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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