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BUG: KCSAN: data-race in __d_instantiate / step_into

read-write to 0xffff8881439ceb40 of 4 bytes by task 16098 on cpu 1:
 __d_instantiate+0x2cd/0x3c0 fs/dcache.c:1855
 d_instantiate+0x59/0x80 fs/dcache.c:1880
 shmem_symlink+0x364/0x390 mm/shmem.c:3517
 vfs_symlink+0xc2/0x1a0 fs/namei.c:4484
 do_symlinkat+0xe3/0x340 fs/namei.c:4510
 __do_sys_symlink fs/namei.c:4531 [inline]
 __se_sys_symlink fs/namei.c:4529 [inline]
 __x64_sys_symlink+0x56/0x60 fs/namei.c:4529
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881439ceb40 of 4 bytes by task 18157 on cpu 0:
 __d_entry_type include/linux/dcache.h:392 [inline]
 d_is_symlink include/linux/dcache.h:422 [inline]
 step_into+0x12f/0x800 fs/namei.c:1848
 walk_component+0x164/0x230 fs/namei.c:2011
 lookup_last fs/namei.c:2462 [inline]
 path_lookupat+0x10a/0x2a0 fs/namei.c:2486
 filename_lookup+0x126/0x300 fs/namei.c:2515
 vfs_statx+0xa2/0x320 fs/stat.c:244
 vfs_fstatat+0xcd/0x100 fs/stat.c:304
 __do_sys_newfstatat fs/stat.c:468 [inline]
 __se_sys_newfstatat+0x58/0x260 fs/stat.c:462
 __x64_sys_newfstatat+0x55/0x60 fs/stat.c:462
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000008 -> 0x00600008

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18157 Comm: udevd Not tainted 6.8.0-rc5-syzkaller-00381-g70ff1fe626a1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
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I/O error, dev loop4, sector 0 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0