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BUG: KCSAN: data-race in d_alloc_parallel / d_set_d_op

write to 0xffff88812282a6c0 of 4 bytes by task 25494 on cpu 1:
 d_set_d_op+0x10f/0x220 fs/dcache.c:1931
 proc_pident_instantiate+0x16c/0x190 fs/proc/base.c:2626
 proc_pident_lookup fs/proc/base.c:2649 [inline]
 proc_tgid_base_lookup+0x10c/0x180 fs/proc/base.c:3313
 __lookup_slow+0x182/0x250 fs/namei.c:1707
 lookup_slow fs/namei.c:1724 [inline]
 walk_component+0x2b6/0x360 fs/namei.c:2020
 link_path_walk+0x52f/0x990
 path_openat+0x1a6/0x1f30 fs/namei.c:3605
 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 0xffff88812282a6c0 of 4 bytes by task 25512 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_slow+0x80/0x250 fs/namei.c:1692
 lookup_slow fs/namei.c:1724 [inline]
 walk_component+0x2b6/0x360 fs/namei.c:2020
 link_path_walk+0x52f/0x990
 path_openat+0x1a6/0x1f30 fs/namei.c:3605
 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: 25512 Comm: syz-executor.2 Not tainted 5.17.0-rc4-syzkaller-00054-gf71077a4d84b-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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