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BUG: KCSAN: data-race in copy_mm / percpu_counter_destroy_many

write to 0xffff888103756078 of 8 bytes by task 27491 on cpu 1:
 __list_del include/linux/list.h:241 [inline]
 __list_del_entry include/linux/list.h:264 [inline]
 list_del include/linux/list.h:275 [inline]
 percpu_counter_destroy_many+0xbd/0x320 lib/percpu_counter.c:244
 __mmdrop+0x1ef/0x370 kernel/fork.c:741
 mmdrop include/linux/sched/mm.h:55 [inline]
 __mmput+0x1be/0x1c0 kernel/fork.c:1205
 mmput+0x40/0x50 kernel/fork.c:1216
 exit_mm+0x113/0x1a0 kernel/exit.c:617
 do_exit+0x438/0x1510 kernel/exit.c:999
 do_group_exit+0xfe/0x140 kernel/exit.c:1154
 get_signal+0xe07/0xf10 kernel/signal.c:3051
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
 exit_to_user_mode_loop+0x15d/0x8c0 kernel/entry/common.c:101
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:336 [inline]
 do_syscall_64+0x212/0x360 arch/x86/entry/syscall_64.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888103755b00 of 1728 bytes by task 27486 on cpu 0:
 dup_mm kernel/fork.c:1537 [inline]
 copy_mm+0xd6/0x340 kernel/fork.c:1595
 copy_process+0x10ad/0x2340 kernel/fork.c:2307
 kernel_clone+0x1c0/0x5f0 kernel/fork.c:2766
 __do_sys_clone kernel/fork.c:2908 [inline]
 __se_sys_clone kernel/fork.c:2892 [inline]
 __x64_sys_clone+0x143/0x180 kernel/fork.c:2892
 x64_sys_call+0x2479/0x2550 arch/x86/include/generated/asm/syscalls_64.h:57
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 27486 Comm: dhcpcd-run-hook Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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