==================================================================
BUG: KCSAN: data-race in find_alive_thread / get_signal

read to 0xffff8880b4756064 of 4 bytes by task 12324 on cpu 1:
 find_alive_thread+0xdd/0x130 kernel/exit.c:495
 find_new_reaper kernel/exit.c:548 [inline]
 forget_original_parent kernel/exit.c:623 [inline]
 exit_notify kernel/exit.c:656 [inline]
 do_exit+0x65c/0x18c0 kernel/exit.c:818
 do_group_exit+0xb4/0x1c0 kernel/exit.c:895
 __do_sys_exit_group kernel/exit.c:906 [inline]
 __se_sys_exit_group kernel/exit.c:904 [inline]
 __x64_sys_exit_group+0x2e/0x30 kernel/exit.c:904
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff8880b4756064 of 4 bytes by task 12328 on cpu 0:
 get_signal+0x7c7/0x1320 kernel/signal.c:2714
 do_signal+0x2f/0x6c0 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:160
 prepare_exit_to_usermode+0x1a6/0x1d0 arch/x86/entry/common.c:195
 swapgs_restore_regs_and_return_to_usermode+0x0/0x40

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 12328 Comm: syz-executor.1 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: 12328 Comm: syz-executor.1 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]
 __tsan_unaligned_write4+0xc7/0x110 kernel/kcsan/core.c:588
 get_signal+0x7c7/0x1320 kernel/signal.c:2714
 do_signal+0x2f/0x6c0 arch/x86/kernel/signal.c:815
 exit_to_usermode_loop+0x250/0x2c0 arch/x86/entry/common.c:160
 prepare_exit_to_usermode+0x1a6/0x1d0 arch/x86/entry/common.c:195
 ret_from_intr+0x21/0x21
RIP: 0033:0x45d753
Code: 17 48 89 d0 64 83 3c 25 18 00 00 00 00 74 01 f0 48 0f b1 3d ef b1 61 00 48 39 c2 75 da f3 c3 0f 1f 84 00 00 00 00 00 48 63 ff <b8> e4 00 00 00 0f 05 48 3d 00 f0 ff ff 77 06 f3 c3 0f 1f 40 00 48
RSP: 002b:00007f7f8708dc58 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000000 RBX: 000000000075bf28 RCX: 000000000045a919
RDX: 0000000000000000 RSI: 00007f7f8708dc60 RDI: 0000000000000001
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000075bf2c
R13: 00000000004c3ce8 R14: 00000000004d9390 R15: 000000000075bf2c
Kernel Offset: disabled
Rebooting in 86400 seconds..