syzbot

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BUG: KCSAN: data-race in d_alloc_parallel / d_set_d_op

read-write to 0xffff88810e241e40 of 4 bytes by task 16844 on cpu 1:
 d_set_d_op+0xfb/0x1f0 fs/dcache.c:1792
 proc_ns_instantiate fs/proc/namespaces.c:114 [inline]
 proc_ns_dir_lookup+0x180/0x220 fs/proc/namespaces.c:172
 lookup_open fs/namei.c:3475 [inline]
 open_last_lookups fs/namei.c:3566 [inline]
 path_openat+0xc85/0x1d80 fs/namei.c:3796
 do_filp_open+0xf7/0x200 fs/namei.c:3826
 do_sys_openat2+0xab/0x120 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_openat fs/open.c:1437 [inline]
 __se_sys_openat fs/open.c:1432 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1432
 x64_sys_call+0x2cad/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810e241e40 of 4 bytes by task 16847 on cpu 0:
 d_in_lookup include/linux/dcache.h:371 [inline]
 d_wait_lookup fs/dcache.c:2443 [inline]
 d_alloc_parallel+0x5ff/0xc70 fs/dcache.c:2531
 lookup_open fs/namei.c:3422 [inline]
 open_last_lookups fs/namei.c:3566 [inline]
 path_openat+0x65e/0x1d80 fs/namei.c:3796
 do_filp_open+0xf7/0x200 fs/namei.c:3826
 do_sys_openat2+0xab/0x120 fs/open.c:1406
 do_sys_open fs/open.c:1421 [inline]
 __do_sys_openat fs/open.c:1437 [inline]
 __se_sys_openat fs/open.c:1432 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1432
 x64_sys_call+0x2cad/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x10000000 -> 0x1000000c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16847 Comm: syz-executor.4 Not tainted 6.9.0-rc4-syzkaller-00031-g96fca68c4fbf #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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