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BUG: KCSAN: data-race in copy_mm / percpu_counter_destroy_many

write to 0xffff88810e9e6030 of 8 bytes by task 21749 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+0x22d/0x3c0 kernel/fork.c:691
 mmdrop include/linux/sched/mm.h:55 [inline]
 __mmput+0x1be/0x1c0 kernel/fork.c:1141
 mmput+0x40/0x50 kernel/fork.c:1152
 exit_mm+0xe4/0x190 kernel/exit.c:582
 do_exit+0x417/0x15c0 kernel/exit.c:949
 do_group_exit+0xff/0x140 kernel/exit.c:1102
 get_signal+0xe59/0xf70 kernel/signal.c:3034
 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x7a/0x100 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 0xffff88810e9e5c00 of 1408 bytes by task 21750 on cpu 0:
 dup_mm kernel/fork.c:1479 [inline]
 copy_mm+0xe2/0x370 kernel/fork.c:1537
 copy_process+0xd08/0x2000 kernel/fork.c:2175
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2605
 __do_sys_clone kernel/fork.c:2748 [inline]
 __se_sys_clone kernel/fork.c:2732 [inline]
 __x64_sys_clone+0xe6/0x120 kernel/fork.c:2732
 x64_sys_call+0x119c/0x2ff0 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: 21750 Comm: syz.1.5766 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
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