==================================================================
BUG: KCSAN: data-race in alloc_fd / do_select

write to 0xffff88811dedfd80 of 8 bytes by task 14214 on cpu 1:
 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
 sock_map_fd net/socket.c:485 [inline]
 __sys_socket+0xe8/0x220 net/socket.c:1672
 __do_sys_socket net/socket.c:1677 [inline]
 __se_sys_socket net/socket.c:1675 [inline]
 __x64_sys_socket+0x3f/0x50 net/socket.c:1675
 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 0xffff88811dedfd80 of 8 bytes by task 14215 on cpu 0:
 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
 kern_select fs/select.c:722 [inline]
 __do_sys_select fs/select.c:729 [inline]
 __se_sys_select+0x1c7/0x200 fs/select.c:726
 __x64_sys_select+0x67/0x80 fs/select.c:726
 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: 0x0000000000003fff -> 0x000000000001ffff

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 14215 Comm: syz-executor.3 Not tainted 6.4.0-syzkaller-01761-g6aeadf7896bf #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023
==================================================================