syzbot

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BUG: KCSAN: data-race in d_alloc_parallel / d_set_d_op

write to 0xffff88813ea64000 of 4 bytes by task 5036 on cpu 1:
 d_set_d_op+0x10f/0x220 fs/dcache.c:1931
 proc_ns_instantiate fs/proc/namespaces.c:114 [inline]
 proc_ns_dir_lookup+0x186/0x220 fs/proc/namespaces.c:172
 lookup_open fs/namei.c:3308 [inline]
 open_last_lookups fs/namei.c:3400 [inline]
 path_openat+0xb27/0x1f30 fs/namei.c:3606
 do_filp_open+0x105/0x220 fs/namei.c:3636
 do_sys_openat2+0xb5/0x2b0 fs/open.c:1214
 do_sys_open fs/open.c:1230 [inline]
 __do_sys_openat fs/open.c:1246 [inline]
 __se_sys_openat fs/open.c:1241 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1241
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88813ea64000 of 4 bytes by task 5037 on cpu 0:
 d_in_lookup include/linux/dcache.h:356 [inline]
 d_wait_lookup fs/dcache.c:2581 [inline]
 d_alloc_parallel+0x669/0xd00 fs/dcache.c:2669
 lookup_open fs/namei.c:3254 [inline]
 open_last_lookups fs/namei.c:3400 [inline]
 path_openat+0x687/0x1f30 fs/namei.c:3606
 do_filp_open+0x105/0x220 fs/namei.c:3636
 do_sys_openat2+0xb5/0x2b0 fs/open.c:1214
 do_sys_open fs/open.c:1230 [inline]
 __do_sys_openat fs/open.c:1246 [inline]
 __se_sys_openat fs/open.c:1241 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1241
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x10000000 -> 0x1000000c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 5037 Comm: syz-executor.2 Not tainted 5.17.0-syzkaller-00192-geaa54b1458ca-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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