==================================================================
BUG: KCSAN: data-race in copy_process / release_task

write to 0xffffffff8927a410 of 4 bytes by task 23266 on cpu 1:
 __unhash_process kernel/exit.c:73 [inline]
 __exit_signal kernel/exit.c:147 [inline]
 release_task+0x6c8/0xb90 kernel/exit.c:198
 exit_notify kernel/exit.c:680 [inline]
 do_exit+0x1140/0x16e0 kernel/exit.c:826
 call_usermodehelper_exec_async+0x2da/0x2e0 kernel/umh.c:125
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293

read to 0xffffffff8927a410 of 4 bytes by task 23254 on cpu 0:
 copy_process+0xac4/0x3300 kernel/fork.c:1980
 _do_fork+0xf1/0x660 kernel/fork.c:2443
 __do_sys_clone kernel/fork.c:2599 [inline]
 __se_sys_clone kernel/fork.c:2580 [inline]
 __x64_sys_clone+0xfb/0x120 kernel/fork.c:2580
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 23254 Comm: syz-executor.1 Not tainted 5.8.0-rc3-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: 23254 Comm: syz-executor.1 Not tainted 5.8.0-rc3-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+0x10f/0x19d lib/dump_stack.c:118
 panic+0x207/0x64a kernel/panic.c:231
 kcsan_report+0x684/0x690 kernel/kcsan/report.c:626
 kcsan_setup_watchpoint+0x453/0x4d0 kernel/kcsan/core.c:519
 copy_process+0xac4/0x3300 kernel/fork.c:1980
 _do_fork+0xf1/0x660 kernel/fork.c:2443
 __do_sys_clone kernel/fork.c:2599 [inline]
 __se_sys_clone kernel/fork.c:2580 [inline]
 __x64_sys_clone+0xfb/0x120 kernel/fork.c:2580
 do_syscall_64+0x51/0xb0 arch/x86/entry/common.c:359
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45f4f9
Code: Bad RIP value.
RSP: 002b:00007fff0a575418 EFLAGS: 00000202 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f076196d700 RCX: 000000000045f4f9
RDX: 00007f076196d9d0 RSI: 00007f076196cdb0 RDI: 00000000003d0f00
RBP: 00007fff0a575640 R08: 00007f076196d700 R09: 00007f076196d700
R10: 00007f076196d9d0 R11: 0000000000000202 R12: 0000000000000000
R13: 00007fff0a5754cf R14: 00007f076196d9c0 R15: 000000000078bfac
Kernel Offset: disabled
Rebooting in 86400 seconds..