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BUG: KCSAN: data-race in copy_mm / percpu_counter_destroy_many

write to 0xffff88810c019b08 of 8 bytes by task 5991 on cpu 1:
 __list_del include/linux/list.h:195 [inline]
 __list_del_entry include/linux/list.h:218 [inline]
 list_del include/linux/list.h:229 [inline]
 percpu_counter_destroy_many+0xc7/0x2b0 lib/percpu_counter.c:244
 __mmdrop+0x22e/0x350 kernel/fork.c:688
 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+0x187/0x2b0 kernel/sched/core.c:5289
 context_switch kernel/sched/core.c:5399 [inline]
 __schedule+0x6a8/0xb30 kernel/sched/core.c:6785
 preempt_schedule_common kernel/sched/core.c:6965 [inline]
 __cond_resched+0x4e/0x90 kernel/sched/core.c:7310
 _cond_resched include/linux/sched.h:2097 [inline]
 __sys_sendmmsg+0x216/0x300 net/socket.c:2723
 __do_sys_sendmmsg net/socket.c:2736 [inline]
 __se_sys_sendmmsg net/socket.c:2733 [inline]
 __x64_sys_sendmmsg+0x57/0x70 net/socket.c:2733
 x64_sys_call+0x2f2f/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:308
 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

read to 0xffff88810c019700 of 1408 bytes by task 6000 on cpu 0:
 dup_mm kernel/fork.c:1471 [inline]
 copy_mm+0xe2/0x370 kernel/fork.c:1529
 copy_process+0xcf1/0x1fe0 kernel/fork.c:2169
 kernel_clone+0x16c/0x5b0 kernel/fork.c:2599
 __do_sys_clone kernel/fork.c:2742 [inline]
 __se_sys_clone kernel/fork.c:2726 [inline]
 __x64_sys_clone+0xe6/0x120 kernel/fork.c:2726
 x64_sys_call+0x2c59/0x2fb0 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: 0 UID: 0 PID: 6000 Comm: dhcpcd-run-hook Not tainted 6.15.0-syzkaller-12426-ge271ed52b344 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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