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BUG: KCSAN: data-race in pcpu_alloc_noprof / pcpu_free_area

read-write to 0xffffffff88c092ec of 4 bytes by task 2096 on cpu 0:
 pcpu_update_empty_pages mm/percpu.c:602 [inline]
 pcpu_block_update_hint_free mm/percpu.c:1044 [inline]
 pcpu_free_area+0x4dc/0x570 mm/percpu.c:1302
 free_percpu+0x1c6/0xb30 mm/percpu.c:2246
 bpf_array_free_percpu kernel/bpf/arraymap.c:27 [inline]
 array_map_free+0x28b/0x300 kernel/bpf/arraymap.c:476
 bpf_map_free kernel/bpf/syscall.c:838 [inline]
 bpf_map_free_deferred+0xb0/0x140 kernel/bpf/syscall.c:862
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3310
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

read to 0xffffffff88c092ec of 4 bytes by task 12609 on cpu 1:
 pcpu_alloc_noprof+0x9b6/0x10a0 mm/percpu.c:1894
 snmp6_alloc_dev net/ipv6/addrconf.c:344 [inline]
 ipv6_add_dev+0x2ee/0xab0 net/ipv6/addrconf.c:409
 addrconf_notify+0x407/0x950 net/ipv6/addrconf.c:3655
 notifier_call_chain kernel/notifier.c:93 [inline]
 raw_notifier_call_chain+0x6f/0x1d0 kernel/notifier.c:461
 call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:1996
 call_netdevice_notifiers_extack net/core/dev.c:2034 [inline]
 call_netdevice_notifiers net/core/dev.c:2048 [inline]
 register_netdevice+0xca9/0xe30 net/core/dev.c:10626
 wg_newlink+0x290/0x450 drivers/net/wireguard/device.c:368
 rtnl_newlink_create+0x1ab/0x5c0 net/core/rtnetlink.c:3774
 __rtnl_newlink net/core/rtnetlink.c:3891 [inline]
 rtnl_newlink+0xe3a/0x1200 net/core/rtnetlink.c:4001
 rtnetlink_rcv_msg+0x651/0x710 net/core/rtnetlink.c:6911
 netlink_rcv_skb+0x12c/0x230 net/netlink/af_netlink.c:2541
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6938
 netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]
 netlink_unicast+0x599/0x670 net/netlink/af_netlink.c:1347
 netlink_sendmsg+0x5cc/0x6e0 net/netlink/af_netlink.c:1891
 sock_sendmsg_nosec net/socket.c:711 [inline]
 __sock_sendmsg+0x140/0x180 net/socket.c:726
 ____sys_sendmsg+0x312/0x410 net/socket.c:2583
 ___sys_sendmsg net/socket.c:2637 [inline]
 __sys_sendmsg+0x19d/0x230 net/socket.c:2669
 __do_sys_sendmsg net/socket.c:2674 [inline]
 __se_sys_sendmsg net/socket.c:2672 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2672
 x64_sys_call+0x2734/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000099 -> 0x0000009a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 12609 Comm: syz.0.3362 Tainted: G        W          6.12.0-syzkaller-07749-g28eb75e178d3 #0
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
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wireguard0: entered promiscuous mode
wireguard0: entered allmulticast mode