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BUG: KCSAN: data-race in d_alloc_parallel / d_set_d_op

read-write to 0xffff888121b4d180 of 4 bytes by task 8987 on cpu 1:
 d_set_d_op+0xf0/0x1e0 fs/dcache.c:1932
 proc_ns_instantiate fs/proc/namespaces.c:114 [inline]
 proc_ns_dir_lookup+0x542/0x5d0 fs/proc/namespaces.c:172
 lookup_open fs/namei.c:3391 [inline]
 open_last_lookups fs/namei.c:3481 [inline]
 path_openat+0xb1c/0x1b00 fs/namei.c:3710
 do_filp_open+0x105/0x220 fs/namei.c:3740
 do_sys_openat2+0xb5/0x2a0 fs/open.c:1310
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_openat fs/open.c:1342 [inline]
 __se_sys_openat fs/open.c:1337 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1337
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888121b4d180 of 4 bytes by task 8988 on cpu 0:
 d_in_lookup include/linux/dcache.h:359 [inline]
 d_wait_lookup fs/dcache.c:2619 [inline]
 d_alloc_parallel+0x5f5/0xc30 fs/dcache.c:2707
 lookup_open fs/namei.c:3338 [inline]
 open_last_lookups fs/namei.c:3481 [inline]
 path_openat+0x658/0x1b00 fs/namei.c:3710
 do_filp_open+0x105/0x220 fs/namei.c:3740
 do_sys_openat2+0xb5/0x2a0 fs/open.c:1310
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_openat fs/open.c:1342 [inline]
 __se_sys_openat fs/open.c:1337 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1337
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x10000000 -> 0x1000000c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 8988 Comm: syz-executor.2 Not tainted 6.1.0-rc1-syzkaller-00093-g6d36c728bc2e-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
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