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BUG: KCSAN: data-race in d_alloc_parallel / d_set_d_op

read to 0xffff888128d1c780 of 4 bytes by task 3201 on cpu 0:
 d_wait_lookup fs/dcache.c:2502 [inline]
 d_alloc_parallel+0x884/0xe00 fs/dcache.c:2590
 __lookup_slow+0xb4/0x2a0 fs/namei.c:1648
 lookup_slow+0x4f/0x70 fs/namei.c:1682
 walk_component+0x490/0xd90 fs/namei.c:1802
 link_path_walk.part.0+0x5d3/0xa90 fs/namei.c:2128
 link_path_walk fs/namei.c:2059 [inline]
 path_openat+0x14f/0x3580 fs/namei.c:3536
 do_filp_open+0x11e/0x1b0 fs/namei.c:3567
 do_sys_open+0x3b3/0x4f0 fs/open.c:1097
 __do_sys_open fs/open.c:1115 [inline]
 __se_sys_open fs/open.c:1110 [inline]
 __x64_sys_open+0x55/0x70 fs/open.c:1110
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff888128d1c780 of 4 bytes by task 3200 on cpu 1:
 d_set_d_op+0x17b/0x230 fs/dcache.c:1856
 simple_lookup fs/libfs.c:70 [inline]
 simple_lookup+0xaa/0xb0 fs/libfs.c:65
 __lookup_slow+0x129/0x2a0 fs/namei.c:1665
 lookup_slow+0x4f/0x70 fs/namei.c:1682
 walk_component+0x490/0xd90 fs/namei.c:1802
 link_path_walk.part.0+0x5d3/0xa90 fs/namei.c:2128
 link_path_walk fs/namei.c:2059 [inline]
 path_openat+0x14f/0x3580 fs/namei.c:3536
 do_filp_open+0x11e/0x1b0 fs/namei.c:3567
 do_sys_open+0x3b3/0x4f0 fs/open.c:1097
 __do_sys_open fs/open.c:1115 [inline]
 __se_sys_open fs/open.c:1110 [inline]
 __x64_sys_open+0x55/0x70 fs/open.c:1110
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3200 Comm: syz-executor.3 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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