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BUG: KCSAN: data-race in __d_instantiate / lookup_fast

read-write to 0xffff8881bab13b40 of 4 bytes by task 19518 on cpu 0:
 __d_instantiate+0x2cd/0x3c0 fs/dcache.c:1855
 d_instantiate_new+0x5c/0xf0 fs/dcache.c:1899
 ext4_add_nondir+0x16c/0x190 fs/ext4/namei.c:2798
 ext4_symlink+0x4dc/0x590 fs/ext4/namei.c:3434
 vfs_symlink+0xc2/0x1a0 fs/namei.c:4480
 do_symlinkat+0xe3/0x340 fs/namei.c:4506
 __do_sys_symlink fs/namei.c:4527 [inline]
 __se_sys_symlink fs/namei.c:4525 [inline]
 __x64_sys_symlink+0x56/0x60 fs/namei.c:4525
 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 0xffff8881bab13b40 of 4 bytes by task 19519 on cpu 1:
 d_revalidate fs/namei.c:861 [inline]
 lookup_fast+0xd9/0x290 fs/namei.c:1642
 open_last_lookups fs/namei.c:3533 [inline]
 path_openat+0x446/0x1d40 fs/namei.c:3795
 do_filp_open+0xf6/0x200 fs/namei.c:3825
 do_sys_openat2+0xab/0x110 fs/open.c:1404
 do_sys_open fs/open.c:1419 [inline]
 __do_sys_openat fs/open.c:1435 [inline]
 __se_sys_openat fs/open.c:1430 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1430
 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: 0x00000000 -> 0x00680000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19519 Comm: syz-executor.3 Tainted: G        W          6.8.0-rc2-syzkaller-00199-g021533194476 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
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