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BUG: KCSAN: data-race in __d_instantiate / lookup_fast

read-write to 0xffff88810a139c00 of 4 bytes by task 14678 on cpu 1:
 __d_instantiate+0x2cd/0x3b0 fs/dcache.c:2011
 d_instantiate_new+0x5c/0xf0 fs/dcache.c:2055
 ext4_add_nondir+0x161/0x190 fs/ext4/namei.c:2797
 ext4_create+0x20e/0x2f0 fs/ext4/namei.c:2837
 vfs_create+0x15f/0x250 fs/namei.c:3194
 do_mknodat+0x267/0x3d0 fs/namei.c:4045
 __do_sys_mknodat fs/namei.c:4073 [inline]
 __se_sys_mknodat fs/namei.c:4070 [inline]
 __x64_sys_mknodat+0x62/0x70 fs/namei.c:4070
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88810a139c00 of 4 bytes by task 14679 on cpu 0:
 d_revalidate fs/namei.c:858 [inline]
 lookup_fast+0xd9/0x290 fs/namei.c:1639
 walk_component+0x3f/0x230 fs/namei.c:1994
 lookup_last fs/namei.c:2455 [inline]
 path_lookupat+0x10a/0x2a0 fs/namei.c:2479
 filename_lookup+0x126/0x300 fs/namei.c:2508
 do_linkat+0xf0/0x5f0 fs/namei.c:4652
 __do_sys_linkat fs/namei.c:4700 [inline]
 __se_sys_linkat fs/namei.c:4697 [inline]
 __x64_sys_linkat+0x90/0xa0 fs/namei.c:4697
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000000 -> 0x00480000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14679 Comm: syz-executor.1 Tainted: G        W          6.4.0-syzkaller-08686-ge55e5df193d2 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
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