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BUG: KCSAN: data-race in pcpu_alloc / pcpu_alloc

read-write to 0xffffffff86f3d634 of 4 bytes by task 3130 on cpu 0:
 pcpu_update_empty_pages mm/percpu.c:602 [inline]
 pcpu_chunk_populated mm/percpu.c:1531 [inline]
 pcpu_alloc+0xa1f/0x1280 mm/percpu.c:1863
 __alloc_percpu+0x24/0x30 mm/percpu.c:1943
 xt_percpu_counter_alloc+0x72/0x110 net/netfilter/x_tables.c:1930
 find_check_entry net/ipv6/netfilter/ip6_tables.c:547 [inline]
 translate_table+0x99f/0x1040 net/ipv6/netfilter/ip6_tables.c:735
 ip6t_register_table+0x9a/0x440 net/ipv6/netfilter/ip6_tables.c:1745
 ip6table_nat_table_init+0x42/0x280 net/ipv6/netfilter/ip6table_nat.c:116
 xt_find_table_lock+0x190/0x260 net/netfilter/x_tables.c:1259
 xt_request_find_table_lock+0x26/0xa0 net/netfilter/x_tables.c:1284
 get_info net/ipv6/netfilter/ip6_tables.c:981 [inline]
 do_ip6t_get_ctl+0x552/0xbf0 net/ipv6/netfilter/ip6_tables.c:1662
 nf_getsockopt+0x184/0x1a0 net/netfilter/nf_sockopt.c:116
 ipv6_getsockopt+0x183/0x1e0 net/ipv6/ipv6_sockglue.c:1499
 tcp_getsockopt+0xa7/0xd0 net/ipv4/tcp.c:4409
 sock_common_getsockopt+0x57/0x70 net/core/sock.c:3641
 __sys_getsockopt+0x175/0x1e0 net/socket.c:2315
 __do_sys_getsockopt net/socket.c:2330 [inline]
 __se_sys_getsockopt net/socket.c:2327 [inline]
 __x64_sys_getsockopt+0x66/0x80 net/socket.c:2327
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff86f3d634 of 4 bytes by task 3129 on cpu 1:
 pcpu_alloc+0xa59/0x1280 mm/percpu.c:1870
 __alloc_percpu_gfp+0x26/0x30 mm/percpu.c:1930
 fib_nh_common_init+0x48/0x2b0 net/ipv4/fib_semantics.c:590
 fib6_nh_init+0xe11/0x15c0 net/ipv6/route.c:3601
 ip6_route_info_create+0x7cb/0xb90 net/ipv6/route.c:3792
 ip6_route_add+0x26/0x100 net/ipv6/route.c:3836
 addrconf_prefix_route net/ipv6/addrconf.c:2425 [inline]
 fixup_permanent_addr net/ipv6/addrconf.c:3500 [inline]
 addrconf_permanent_addr+0x43d/0x5a0 net/ipv6/addrconf.c:3524
 addrconf_notify+0x6d4/0x980 net/ipv6/addrconf.c:3596
 notifier_call_chain kernel/notifier.c:87 [inline]
 raw_notifier_call_chain+0x54/0xb0 kernel/notifier.c:455
 __dev_notify_flags+0x205/0x3d0
 dev_change_flags+0xab/0xd0 net/core/dev.c:8604
 do_setlink+0xa09/0x18c0 net/core/rtnetlink.c:2833
 __rtnl_newlink net/core/rtnetlink.c:3623 [inline]
 rtnl_newlink+0x10cb/0x15a0 net/core/rtnetlink.c:3670
 rtnetlink_rcv_msg+0x807/0x8c0 net/core/rtnetlink.c:6174
 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2574
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6192
 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline]
 netlink_unicast+0x56f/0x640 net/netlink/af_netlink.c:1365
 netlink_sendmsg+0x665/0x770 net/netlink/af_netlink.c:1942
 sock_sendmsg_nosec net/socket.c:724 [inline]
 sock_sendmsg net/socket.c:747 [inline]
 __sys_sendto+0x246/0x300 net/socket.c:2142
 __do_sys_sendto net/socket.c:2154 [inline]
 __se_sys_sendto net/socket.c:2150 [inline]
 __x64_sys_sendto+0x78/0x90 net/socket.c:2150
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0xffffffff -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3129 Comm: syz-executor.0 Not tainted 6.3.0-rc3-syzkaller-00031-g1e760fa3596e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
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