syzbot

==================================================================
BUG: KCSAN: data-race in do_exit / kernel_clone

write to 0xffff888134fd502c of 4 bytes by task 3355 on cpu 0:
 freezer_count include/linux/freezer.h:121 [inline]
 wait_for_vfork_done kernel/fork.c:1278 [inline]
 kernel_clone+0x2e3/0x680 kernel/fork.c:2534
 __do_sys_clone kernel/fork.c:2620 [inline]
 __se_sys_clone kernel/fork.c:2604 [inline]
 __x64_sys_clone+0xb4/0xe0 kernel/fork.c:2604
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888134fd502c of 4 bytes by task 3338 on cpu 1:
 find_alive_thread kernel/exit.c:512 [inline]
 find_new_reaper kernel/exit.c:561 [inline]
 forget_original_parent kernel/exit.c:636 [inline]
 exit_notify kernel/exit.c:669 [inline]
 do_exit+0x56c/0x1560 kernel/exit.c:846
 do_group_exit+0xce/0x1a0 kernel/exit.c:923
 get_signal+0xfc3/0x1610 kernel/signal.c:2818
 arch_do_signal_or_restart+0x2a/0x220 arch/x86/kernel/signal.c:789
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x109/0x190 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x56/0x90 arch/x86/entry/common.c:57
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3338 Comm: syz-executor.0 Not tainted 5.13.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================