syzbot

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BUG: KCSAN: data-race in __alloc_fd / do_select

read to 0xffff88809b722880 of 8 bytes by task 10102 on cpu 1:
 max_select_fd fs/select.c:446 [inline]
 do_select+0x315/0x1020 fs/select.c:487
 core_sys_select+0x312/0x650 fs/select.c:677
 do_pselect.constprop.0+0x11d/0x160 fs/select.c:759
 __do_sys_pselect6 fs/select.c:784 [inline]
 __se_sys_pselect6 fs/select.c:769 [inline]
 __x64_sys_pselect6+0x12e/0x170 fs/select.c:769
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88809b722880 of 8 bytes by task 10077 on cpu 0:
 __set_bit include/asm-generic/bitops/instrumented-non-atomic.h:29 [inline]
 __set_open_fd fs/file.c:241 [inline]
 __alloc_fd+0x200/0x3b0 fs/file.c:519
 get_unused_fd_flags+0x8b/0xc0 fs/file.c:545
 __do_sys_perf_event_open+0x33f/0x1e40 kernel/events/core.c:11227
 __se_sys_perf_event_open kernel/events/core.c:11151 [inline]
 __x64_sys_perf_event_open+0x70/0x90 kernel/events/core.c:11151
 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: 0 PID: 10077 Comm: syz-executor.0 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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