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BUG: KCSAN: data-race in alloc_fd / do_select

write to 0xffff888100cdfc00 of 8 bytes by task 311 on cpu 0:
 instrument_write include/linux/instrumented.h:41 [inline]
 ___set_bit include/asm-generic/bitops/instrumented-non-atomic.h:28 [inline]
 __set_open_fd fs/file.c:262 [inline]
 alloc_fd+0x1d5/0x370 fs/file.c:538
 __get_unused_fd_flags fs/file.c:559 [inline]
 get_unused_fd_flags+0x44/0x50 fs/file.c:564
 do_sys_openat2+0x89/0x110 fs/open.c:1405
 do_sys_open fs/open.c:1422 [inline]
 __do_sys_openat fs/open.c:1438 [inline]
 __se_sys_openat fs/open.c:1433 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1433
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888100cdfc00 of 8 bytes by task 319 on cpu 1:
 max_select_fd fs/select.c:447 [inline]
 do_select+0x2a2/0xf90 fs/select.c:490
 core_sys_select+0x361/0x520 fs/select.c:681
 do_pselect fs/select.c:763 [inline]
 __do_sys_pselect6 fs/select.c:804 [inline]
 __se_sys_pselect6+0x213/0x280 fs/select.c:795
 __x64_sys_pselect6+0x78/0x90 fs/select.c:795
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000007 -> 0x000000000000001f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 319 Comm: syz-executor.5 Not tainted 6.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/03/2023
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