syzbot

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BUG: KCSAN: data-race in alloc_fd / do_select

write to 0xffff88811d62a380 of 8 bytes by task 18368 on cpu 1:
 instrument_write include/linux/instrumented.h:43 [inline]
 ___set_bit include/asm-generic/bitops/instrumented-non-atomic.h:28 [inline]
 __set_open_fd fs/file.c:262 [inline]
 alloc_fd+0x215/0x3a0 fs/file.c:538
 __get_unused_fd_flags fs/file.c:559 [inline]
 get_unused_fd_flags+0x41/0x50 fs/file.c:564
 do_sys_openat2+0x91/0x2a0 fs/open.c:1308
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_openat fs/open.c:1342 [inline]
 __se_sys_openat fs/open.c:1337 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1337
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88811d62a380 of 8 bytes by task 18369 on cpu 0:
 max_select_fd fs/select.c:436 [inline]
 do_select+0x174/0x1020 fs/select.c:490
 core_sys_select+0x368/0x520 fs/select.c:681
 do_pselect fs/select.c:763 [inline]
 __do_sys_pselect6+0x1f4/0x250 fs/select.c:804
 __se_sys_pselect6 fs/select.c:795 [inline]
 __x64_sys_pselect6+0x74/0x80 fs/select.c:795
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000007fff -> 0x000000000003ffff

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18369 Comm: syz-executor.5 Not tainted 6.2.0-rc4-syzkaller-00031-g6e50979a9c87-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/12/2023
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