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BUG: KCSAN: data-race in copy_mm / percpu_counter_destroy_many

write to 0xffff88810561c1d8 of 8 bytes by task 27695 on cpu 0:
 __list_del include/linux/list.h:226 [inline]
 __list_del_entry include/linux/list.h:249 [inline]
 list_del include/linux/list.h:260 [inline]
 percpu_counter_destroy_many+0xc7/0x2b0 lib/percpu_counter.c:244
 __mmdrop+0x25d/0x3f0 kernel/fork.c:737
 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+0x225/0x320 kernel/sched/core.c:5270
 context_switch kernel/sched/core.c:5391 [inline]
 __schedule+0x951/0xd40 kernel/sched/core.c:7189
 __schedule_loop kernel/sched/core.c:7268 [inline]
 schedule+0x5e/0xd0 kernel/sched/core.c:7283
 __exit_to_user_mode_loop kernel/entry/common.c:54 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:98 [inline]
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 irqentry_exit_to_user_mode_prepare include/linux/irq-entry-common.h:244 [inline]
 irqentry_exit_to_user_mode include/linux/irq-entry-common.h:315 [inline]
 irqentry_exit+0x121/0x5d0 kernel/entry/common.c:162
 sysvec_apic_timer_interrupt+0x44/0x80 arch/x86/kernel/apic/apic.c:1061
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697

read to 0xffff88810561bcc0 of 1664 bytes by task 27705 on cpu 1:
 dup_mm kernel/fork.c:1528 [inline]
 copy_mm+0xe1/0x370 kernel/fork.c:1586
 copy_process+0x1087/0x2370 kernel/fork.c:2264
 kernel_clone+0x1c0/0x5f0 kernel/fork.c:2722
 __do_sys_clone kernel/fork.c:2863 [inline]
 __se_sys_clone kernel/fork.c:2847 [inline]
 __x64_sys_clone+0x143/0x180 kernel/fork.c:2847
 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/0x3b0 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: 27705 Comm: dhcpcd-run-hook Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
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