syzbot

==================================================================
BUG: KCSAN: data-race in copy_mm / percpu_counter_destroy_many

write to 0xffff888116c9bdb0 of 8 bytes by task 12841 on cpu 0:
 __list_del include/linux/list.h:203 [inline]
 __list_del_entry include/linux/list.h:226 [inline]
 list_del include/linux/list.h:237 [inline]
 percpu_counter_destroy_many+0xc7/0x2b0 lib/percpu_counter.c:244
 __mmdrop+0x22d/0x3c0 kernel/fork.c:691
 mmdrop include/linux/sched/mm.h:55 [inline]
 __mmput+0x1be/0x1c0 kernel/fork.c:1145
 mmput+0x40/0x50 kernel/fork.c:1156
 exit_mm+0xe4/0x180 kernel/exit.c:582
 do_exit+0x417/0x15c0 kernel/exit.c:954
 do_group_exit+0xff/0x140 kernel/exit.c:1107
 get_signal+0xe58/0xf70 kernel/signal.c:3034
 arch_do_signal_or_restart+0x96/0x440 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x77/0x110 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888116c9b980 of 1408 bytes by task 12839 on cpu 1:
 dup_mm kernel/fork.c:1483 [inline]
 copy_mm+0xe2/0x370 kernel/fork.c:1541
 copy_process+0xd08/0x2000 kernel/fork.c:2181
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2609
 __do_sys_clone kernel/fork.c:2750 [inline]
 __se_sys_clone kernel/fork.c:2734 [inline]
 __x64_sys_clone+0xe6/0x120 kernel/fork.c:2734
 x64_sys_call+0x119c/0x3000 arch/x86/include/generated/asm/syscalls_64.h:57
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 12839 Comm: dhcpcd-run-hook Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================