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BUG: KCSAN: data-race in copy_mm / percpu_counter_destroy_many

write to 0xffff888104555cc8 of 8 bytes by task 4039 on cpu 0:
 __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+0x25a/0x3f0 kernel/fork.c:734
 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+0x186/0x2a0 kernel/sched/core.c:5139
 context_switch kernel/sched/core.c:5259 [inline]
 __schedule+0x85f/0xcd0 kernel/sched/core.c:6863
 preempt_schedule_common kernel/sched/core.c:7047 [inline]
 __cond_resched+0x4e/0x90 kernel/sched/core.c:7376
 might_resched include/linux/kernel.h:61 [inline]
 might_alloc include/linux/sched/mm.h:323 [inline]
 slab_pre_alloc_hook mm/slub.c:4904 [inline]
 slab_alloc_node mm/slub.c:5239 [inline]
 kmem_cache_alloc_node_noprof+0x61/0x4c0 mm/slub.c:5315
 __alloc_skb+0x324/0x4d0 net/core/skbuff.c:679
 alloc_skb include/linux/skbuff.h:1383 [inline]
 nlmsg_new include/net/netlink.h:1055 [inline]
 inet6_netconf_notify_devconf+0x10f/0x1d0 net/ipv6/addrconf.c:593
 __addrconf_sysctl_register+0x30c/0x340 net/ipv6/addrconf.c:7334
 addrconf_sysctl_register+0xe6/0x130 net/ipv6/addrconf.c:7371
 ipv6_add_dev+0x8a2/0xac0 net/ipv6/addrconf.c:460
 addrconf_notify+0x4a5/0x8f0 net/ipv6/addrconf.c:3650
 notifier_call_chain kernel/notifier.c:85 [inline]
 raw_notifier_call_chain+0x6f/0x1b0 kernel/notifier.c:453
 call_netdevice_notifiers_info net/core/dev.c:2230 [inline]
 call_netdevice_notifiers_extack net/core/dev.c:2268 [inline]
 call_netdevice_notifiers+0xab/0x100 net/core/dev.c:2282
 register_netdevice+0xc84/0xdd0 net/core/dev.c:11429
 veth_newlink+0x321/0x770 drivers/net/veth.c:1856
 rtnl_newlink_create+0x1bc/0x620 net/core/rtnetlink.c:3840
 __rtnl_newlink net/core/rtnetlink.c:3957 [inline]
 rtnl_newlink+0xf5b/0x1360 net/core/rtnetlink.c:4072
 rtnetlink_rcv_msg+0x5fe/0x6d0 net/core/rtnetlink.c:6958
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6985
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x5c0/0x690 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x145/0x180 net/socket.c:742
 __sys_sendto+0x268/0x330 net/socket.c:2206
 __do_sys_sendto net/socket.c:2213 [inline]
 __se_sys_sendto net/socket.c:2209 [inline]
 __x64_sys_sendto+0x76/0x90 net/socket.c:2209
 x64_sys_call+0x29a7/0x3000 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881045557c0 of 1664 bytes by task 4078 on cpu 1:
 dup_mm kernel/fork.c:1523 [inline]
 copy_mm+0xe2/0x370 kernel/fork.c:1581
 copy_process+0xcbc/0x1ef0 kernel/fork.c:2221
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2651
 __do_sys_clone kernel/fork.c:2792 [inline]
 __se_sys_clone kernel/fork.c:2776 [inline]
 __x64_sys_clone+0xe6/0x120 kernel/fork.c:2776
 x64_sys_call+0x12d0/0x3000 arch/x86/include/generated/asm/syscalls_64.h:57
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2c0 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: 4078 Comm: dhcpcd-run-hook Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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