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BUG: KCSAN: data-race in pcpu_alloc / pcpu_block_update_hint_alloc

write to 0xffffffff86046740 of 4 bytes by task 7225 on cpu 0:
 pcpu_update_empty_pages mm/percpu.c:575 [inline]
 pcpu_block_update_hint_alloc+0x3f6/0x620 mm/percpu.c:891
 pcpu_alloc_area+0x372/0x510 mm/percpu.c:1228
 pcpu_alloc+0x5b2/0xcf0 mm/percpu.c:1665
 __alloc_percpu+0x2e/0x40 mm/percpu.c:1796
 xt_percpu_counter_alloc+0x105/0x130 net/netfilter/x_tables.c:1842
 find_check_entry.isra.0+0x64/0x590 net/ipv6/netfilter/ip6_tables.c:546
 translate_table+0x7a5/0xcd0 net/ipv6/netfilter/ip6_tables.c:734
 do_replace net/ipv6/netfilter/ip6_tables.c:1153 [inline]
 do_ip6t_set_ctl+0x219/0x311 net/ipv6/netfilter/ip6_tables.c:1681
 nf_sockopt net/netfilter/nf_sockopt.c:106 [inline]
 nf_setsockopt+0x6e/0xb0 net/netfilter/nf_sockopt.c:115
 ipv6_setsockopt net/ipv6/ipv6_sockglue.c:949 [inline]
 ipv6_setsockopt+0x119/0x130 net/ipv6/ipv6_sockglue.c:933
 tcp_setsockopt net/ipv4/tcp.c:3148 [inline]
 tcp_setsockopt+0x7c/0xc0 net/ipv4/tcp.c:3142
 sock_common_setsockopt+0x67/0x90 net/core/sock.c:3147
 __sys_setsockopt+0x1ce/0x370 net/socket.c:2084
 __do_sys_setsockopt net/socket.c:2100 [inline]
 __se_sys_setsockopt net/socket.c:2097 [inline]
 __x64_sys_setsockopt+0x70/0x90 net/socket.c:2097

read to 0xffffffff86046740 of 4 bytes by task 7240 on cpu 1:
 pcpu_alloc+0x3b0/0xcf0 mm/percpu.c:1729
 __alloc_percpu+0x2e/0x40 mm/percpu.c:1796
 alloc_netdev_mqs+0xff/0x860 net/core/dev.c:9201
 rtnl_create_link+0x181/0x4f0 net/core/rtnetlink.c:2931
 veth_newlink+0x1be/0x620 drivers/net/veth.c:1286
 __rtnl_newlink+0xc89/0x1010 net/core/rtnetlink.c:3196
 rtnl_newlink+0x63/0x90 net/core/rtnetlink.c:3254
 rtnetlink_rcv_msg+0x1d3/0x500 net/core/rtnetlink.c:5223
 netlink_rcv_skb+0xb0/0x260 net/netlink/af_netlink.c:2477
 rtnetlink_rcv+0x26/0x30 net/core/rtnetlink.c:5241
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0x354/0x430 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x456/0x770 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg+0x9f/0xc0 net/socket.c:657

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 7240 Comm: syz-executor.5 Not tainted 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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