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BUG: KCSAN: data-race in __d_instantiate / step_into

read-write to 0xffff888106608780 of 4 bytes by task 3563 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:3963
 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 0xffff888106608780 of 4 bytes by task 3021 on cpu 1:
 __follow_mount_rcu fs/namei.c:1570 [inline]
 handle_mounts fs/namei.c:1621 [inline]
 step_into+0xe7/0x840 fs/namei.c:1950
 walk_component+0x169/0x230 fs/namei.c:2118
 lookup_last fs/namei.c:2610 [inline]
 path_lookupat+0x10a/0x2b0 fs/namei.c:2634
 filename_lookup+0x150/0x340 fs/namei.c:2663
 do_readlinkat+0x89/0x210 fs/stat.c:562
 __do_sys_readlink fs/stat.c:599 [inline]
 __se_sys_readlink fs/stat.c:596 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:596
 x64_sys_call+0x28ba/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:90
 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: 3021 Comm: udevd Not tainted 6.12.0-syzkaller-10553-gb86545e02e8c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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