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

read to 0xffff8881252b1900 of 8 bytes by task 18800 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 0xffff8881252b1900 of 8 bytes by task 18798 on cpu 0:
 __clear_bit include/asm-generic/bitops/instrumented-non-atomic.h:45 [inline]
 __clear_open_fd fs/file.c:249 [inline]
 __put_unused_fd+0x7b/0x120 fs/file.c:552
 __close_fd+0xdc/0x140 fs/file.c:634
 __do_sys_close fs/open.c:1193 [inline]
 __se_sys_close fs/open.c:1191 [inline]
 __x64_sys_close+0x49/0xb0 fs/open.c:1191
 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: 18798 Comm: syz-executor.4 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 0 PID: 18798 Comm: syz-executor.4 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x11d/0x181 lib/dump_stack.c:118
 panic+0x210/0x640 kernel/panic.c:221
 kcsan_report.cold+0xc/0xd kernel/kcsan/report.c:313
 kcsan_setup_watchpoint+0x3fe/0x460 kernel/kcsan/core.c:416
 check_access kernel/kcsan/core.c:459 [inline]
 __kcsan_check_access+0xdc/0x120 kernel/kcsan/core.c:551
 __clear_bit include/asm-generic/bitops/instrumented-non-atomic.h:45 [inline]
 __clear_open_fd fs/file.c:249 [inline]
 __put_unused_fd+0x7b/0x120 fs/file.c:552
 __close_fd+0xdc/0x140 fs/file.c:634
 __do_sys_close fs/open.c:1193 [inline]
 __se_sys_close fs/open.c:1191 [inline]
 __x64_sys_close+0x49/0xb0 fs/open.c:1191
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x414ae1
Code: 75 14 b8 03 00 00 00 0f 05 48 3d 01 f0 ff ff 0f 83 04 1b 00 00 c3 48 83 ec 08 e8 0a fc ff ff 48 89 04 24 b8 03 00 00 00 0f 05 <48> 8b 3c 24 48 89 c2 e8 53 fc ff ff 48 89 d0 48 83 c4 08 48 3d 01
RSP: 002b:00007fff44d683c0 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000414ae1
RDX: 0000000000000000 RSI: 0000000000000081 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000762350 R09: ffffffffffffffff
R10: 00007fff44d68490 R11: 0000000000000293 R12: 000000000075bf20
R13: 0000000000000006 R14: 0000000000762358 R15: 000000000075bf2c
Kernel Offset: disabled
Rebooting in 86400 seconds..