KCSAN: data-race in do_exit / exit

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in do_exit / exit_mm kernel	6				2	2008d	2030d	0/29	auto-closed as invalid on 2020/08/22 07:37
upstream	KCSAN: data-race in do_exit / exit_mm (2) kernel	6				1	1946d	1946d	0/29	auto-closed as invalid on 2020/10/23 06:15

================================================================== BUG: KCSAN: data-race in do_exit / exit_mm write to 0xffff88812d74202c of 4 bytes by task 12394 on cpu 0: freezer_count include/linux/freezer.h:121 [inline] freezable_schedule include/linux/freezer.h:173 [inline] exit_mm+0x1e5/0x450 kernel/exit.c:474 do_exit+0x3ff/0x1560 kernel/exit.c:813 do_group_exit+0xce/0x1a0 kernel/exit.c:923 get_signal+0xfc3/0x1610 kernel/signal.c:2835 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 read to 0xffff88812d74202c of 4 bytes by task 12402 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:2835 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 value changed: 0x40404444 -> 0x00404444 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 12402 Comm: syz-executor.4 Not tainted 5.13.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ==================================================================