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BUG: KCSAN: data-race in copy_mm / percpu_counter_destroy_many

write to 0xffff88810006f148 of 8 bytes by task 7599 on cpu 0:
 __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+0x1c9/0x340 kernel/fork.c:741
 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+0x296/0x340 kernel/sched/core.c:5465
 context_switch kernel/sched/core.c:5586 [inline]
 __schedule+0x7a9/0xd40 kernel/sched/core.c:7382
 preempt_schedule_common+0x12/0x40 kernel/sched/core.c:7561
 preempt_schedule_thunk+0x16/0x40 arch/x86/entry/thunk.S:12
 __local_bh_enable_ip+0x68/0x80 kernel/softirq.c:480
 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:237 [inline]
 _raw_spin_unlock_bh+0x17/0x20 kernel/locking/spinlock.c:245
 spin_unlock_bh include/linux/spinlock.h:407 [inline]
 neigh_parms_release+0xbb/0x150 net/core/neighbour.c:1829
 inetdev_destroy net/ipv4/devinet.c:337 [inline]
 inetdev_event+0x740/0xb80 net/ipv4/devinet.c:1645
 notifier_call_chain kernel/notifier.c:86 [inline]
 raw_notifier_call_chain+0x72/0x1a0 kernel/notifier.c:558
 call_netdevice_notifiers_info net/core/dev.c:2313 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2351 [inline]
 call_netdevice_notifiers net/core/dev.c:2365 [inline]
 unregister_netdevice_many_notify+0xe60/0x15a0 net/core/dev.c:12725
 unregister_netdevice_many net/core/dev.c:12796 [inline]
 unregister_netdevice_queue+0x1cd/0x200 net/core/dev.c:12592
 unregister_netdevice include/linux/netdevice.h:3509 [inline]
 nsim_destroy+0x162/0x5a0 drivers/net/netdevsim/netdev.c:1206
 __nsim_dev_port_del+0xd2/0x140 drivers/net/netdevsim/dev.c:1472
 nsim_dev_port_del_all drivers/net/netdevsim/dev.c:1486 [inline]
 nsim_dev_reload_destroy+0x1a1/0x2c0 drivers/net/netdevsim/dev.c:1710
 nsim_drv_remove+0x3e/0x110 drivers/net/netdevsim/dev.c:1725
 nsim_bus_remove+0x15/0x20 drivers/net/netdevsim/bus.c:426
 device_remove drivers/base/dd.c:617 [inline]
 __device_release_driver drivers/base/dd.c:1357 [inline]
 device_release_driver_internal+0x2bb/0x510 drivers/base/dd.c:1380
 device_release_driver+0x19/0x20 drivers/base/dd.c:1403
 bus_remove_device+0x2fa/0x320 drivers/base/bus.c:678
 device_del+0x35f/0x790 drivers/base/core.c:3967
 device_unregister+0x15/0x40 drivers/base/core.c:4008
 nsim_bus_dev_del drivers/net/netdevsim/bus.c:488 [inline]
 del_device_store+0x1c1/0x220 drivers/net/netdevsim/bus.c:243
 bus_attr_store+0x57/0x80 drivers/base/bus.c:172
 sysfs_kf_write+0xfe/0x120 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x1d2/0x2e0 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x57a/0x990 fs/read_write.c:687
 ksys_write+0xdc/0x1a0 fs/read_write.c:739
 __do_sys_write fs/read_write.c:750 [inline]
 __se_sys_write fs/read_write.c:747 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:747
 x64_sys_call+0x154e/0x2550 arch/x86/include/generated/asm/syscalls_64.h:2
 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

read to 0xffff88810006ec00 of 1664 bytes by task 7611 on cpu 1:
 dup_mm kernel/fork.c:1536 [inline]
 copy_mm+0xd1/0x340 kernel/fork.c:1594
 copy_process+0x10e9/0x2400 kernel/fork.c:2320
 kernel_clone+0x1c0/0x5f0 kernel/fork.c:2790
 __do_sys_clone kernel/fork.c:2932 [inline]
 __se_sys_clone kernel/fork.c:2916 [inline]
 __x64_sys_clone+0x143/0x180 kernel/fork.c:2916
 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: 1 UID: 0 PID: 7611 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 10/15/2026
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