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BUG: KCSAN: data-race in __d_drop / fast_dput

write to 0xffff888107e84f10 of 8 bytes by task 9244 on cpu 1:
 __d_drop+0x14d/0x240 fs/dcache.c:576
 d_invalidate+0x50/0x1d0 fs/dcache.c:1701
 lookup_fast+0x296/0x320 fs/namei.c:1881
 lookup_fast_for_open fs/namei.c:4520 [inline]
 open_last_lookups fs/namei.c:4554 [inline]
 path_openat+0x436/0x2050 fs/namei.c:4827
 do_file_open+0x16c/0x290 fs/namei.c:4859
 do_sys_openat2+0x94/0x130 fs/open.c:1366
 do_sys_open fs/open.c:1372 [inline]
 __do_sys_openat fs/open.c:1388 [inline]
 __se_sys_openat fs/open.c:1383 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1383
 x64_sys_call+0x1e39/0x3020 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888107e84f10 of 8 bytes by task 9238 on cpu 0:
 hlist_bl_unhashed include/linux/list_bl.h:54 [inline]
 d_unhashed include/linux/dcache.h:366 [inline]
 retain_dentry fs/dcache.c:753 [inline]
 fast_dput+0x5f/0x2c0 fs/dcache.c:849
 dput+0x24/0x60 fs/dcache.c:924
 end_dirop fs/namei.c:2948 [inline]
 end_creating include/linux/namei.h:126 [inline]
 end_creating_path fs/namei.c:4962 [inline]
 filename_mknodat+0x2cb/0x450 fs/namei.c:5156
 __do_sys_mknodat fs/namei.c:5173 [inline]
 __se_sys_mknodat+0x38/0xf0 fs/namei.c:5169
 __x64_sys_mknodat+0x55/0x70 fs/namei.c:5169
 x64_sys_call+0x312/0x3020 arch/x86/include/generated/asm/syscalls_64.h:260
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff88823783d508 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 9238 Comm: syz.5.1798 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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