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

write to 0xffffffff85a77590 of 4 bytes by task 8877 on cpu 0:
 alloc_pid+0x392/0x5c0 kernel/pid.c:227
 copy_process+0x216a/0x3b50 kernel/fork.c:2029
 _do_fork+0xfe/0x6e0 kernel/fork.c:2366
 __do_sys_clone kernel/fork.c:2521 [inline]
 __se_sys_clone kernel/fork.c:2502 [inline]
 __x64_sys_clone+0x12b/0x160 kernel/fork.c:2502
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffffff85a77590 of 4 bytes by task 8745 on cpu 1:
 copy_process+0x2844/0x3b50 kernel/fork.c:2163
 _do_fork+0xfe/0x6e0 kernel/fork.c:2366
 __do_sys_clone kernel/fork.c:2521 [inline]
 __se_sys_clone kernel/fork.c:2502 [inline]
 __x64_sys_clone+0x12b/0x160 kernel/fork.c:2502
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8745 Comm: udevd Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
Kernel panic - not syncing: panic_on_warn set ...
CPU: 1 PID: 8745 Comm: udevd Not tainted 5.4.0-rc3+ #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+0xf5/0x159 lib/dump_stack.c:113
 panic+0x210/0x640 kernel/panic.c:221
 kcsan_report.cold+0xc/0x10 kernel/kcsan/report.c:302
 __kcsan_setup_watchpoint+0x32e/0x4a0 kernel/kcsan/core.c:411
 __tsan_read4 kernel/kcsan/kcsan.c:35 [inline]
 __tsan_read4+0x2c/0x30 kernel/kcsan/kcsan.c:35
 copy_process+0x2844/0x3b50 kernel/fork.c:2163
 _do_fork+0xfe/0x6e0 kernel/fork.c:2366
 __do_sys_clone kernel/fork.c:2521 [inline]
 __se_sys_clone kernel/fork.c:2502 [inline]
 __x64_sys_clone+0x12b/0x160 kernel/fork.c:2502
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x7f82cb2f7f46
Code: f7 d8 64 89 04 25 d4 02 00 00 64 4c 8b 14 25 10 00 00 00 31 d2 49 81 c2 d0 02 00 00 31 f6 bf 11 00 20 01 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 0f 87 31 01 00 00 85 c0 41 89 c4 0f 85 3b 01 00
RSP: 002b:00007fff16a47ee0 EFLAGS: 00000246 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007fff16a47ee0 RCX: 00007f82cb2f7f46
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011
RBP: 00007fff16a47f40 R08: 0000000000002229 R09: 0000000000002229
R10: 00007f82cbc14a70 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fff16a47f00 R14: 0000000000000005 R15: 0000000000000005
Shutting down cpus with NMI
Kernel Offset: disabled
Rebooting in 86400 seconds..