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BUG: KCSAN: data-race in copy_mm / percpu_counter_destroy_many

write to 0xffff888104725cc8 of 8 bytes by task 4490 on cpu 1:
 __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+0x25d/0x3f0 kernel/fork.c:735
 mmdrop include/linux/sched/mm.h:55 [inline]
 mmdrop_sched include/linux/sched/mm.h:83 [inline]
 mmdrop_lazy_tlb_sched include/linux/sched/mm.h:110 [inline]
 finish_task_switch+0x184/0x280 kernel/sched/core.c:5177
 context_switch kernel/sched/core.c:5298 [inline]
 __schedule+0x806/0xce0 kernel/sched/core.c:6907
 __schedule_loop kernel/sched/core.c:6989 [inline]
 schedule+0x5e/0xd0 kernel/sched/core.c:7004
 do_nanosleep+0x95/0x330 kernel/time/hrtimer.c:2124
 hrtimer_nanosleep+0x207/0x3d0 kernel/time/hrtimer.c:2171
 common_nsleep+0x62/0x80 kernel/time/posix-timers.c:1345
 __do_sys_clock_nanosleep kernel/time/posix-timers.c:1391 [inline]
 __se_sys_clock_nanosleep+0x223/0x260 kernel/time/posix-timers.c:1368
 __x64_sys_clock_nanosleep+0x55/0x70 kernel/time/posix-timers.c:1368
 x64_sys_call+0x146e/0x3020 arch/x86/include/generated/asm/syscalls_64.h:231
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881047257c0 of 1664 bytes by task 4501 on cpu 0:
 dup_mm kernel/fork.c:1524 [inline]
 copy_mm+0xe1/0x370 kernel/fork.c:1582
 copy_process+0xe22/0x20c0 kernel/fork.c:2223
 kernel_clone+0x16b/0x5b0 kernel/fork.c:2654
 __do_sys_clone kernel/fork.c:2795 [inline]
 __se_sys_clone kernel/fork.c:2779 [inline]
 __x64_sys_clone+0x143/0x180 kernel/fork.c:2779
 x64_sys_call+0x1222/0x3020 arch/x86/include/generated/asm/syscalls_64.h:57
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4501 Comm: dhcpcd-run-hook Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
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