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BUG: KCSAN: data-race in pcpu_alloc_noprof / pcpu_block_update_hint_alloc

read-write to 0xffffffff8841f6ac of 4 bytes by task 4848 on cpu 0:
 pcpu_update_empty_pages mm/percpu.c:602 [inline]
 pcpu_block_update_hint_alloc+0x5db/0x6a0 mm/percpu.c:923
 pcpu_alloc_area+0x488/0x4b0 mm/percpu.c:1258
 pcpu_alloc_noprof+0x4b3/0x10c0 mm/percpu.c:1834
 xt_percpu_counter_alloc+0x79/0x110 net/netfilter/x_tables.c:1931
 find_check_entry net/ipv6/netfilter/ip6_tables.c:545 [inline]
 translate_table+0x9b1/0x1040 net/ipv6/netfilter/ip6_tables.c:733
 do_replace net/ipv6/netfilter/ip6_tables.c:1154 [inline]
 do_ip6t_set_ctl+0x7cc/0x8c0 net/ipv6/netfilter/ip6_tables.c:1644
 nf_setsockopt+0x195/0x1b0 net/netfilter/nf_sockopt.c:101
 ipv6_setsockopt+0x126/0x140 net/ipv6/ipv6_sockglue.c:999
 tcp_setsockopt+0x93/0xb0 net/ipv4/tcp.c:3765
 sock_common_setsockopt+0x64/0x80 net/core/sock.c:3726
 do_sock_setsockopt net/socket.c:2312 [inline]
 __sys_setsockopt+0x1d8/0x250 net/socket.c:2335
 __do_sys_setsockopt net/socket.c:2344 [inline]
 __se_sys_setsockopt net/socket.c:2341 [inline]
 __x64_sys_setsockopt+0x66/0x80 net/socket.c:2341
 x64_sys_call+0x1183/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:55
 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

read to 0xffffffff8841f6ac of 4 bytes by task 4889 on cpu 1:
 pcpu_alloc_noprof+0x9a7/0x10c0 mm/percpu.c:1894
 dst_cache_init+0x2e/0x80 net/core/dst_cache.c:145
 ip_tunnel_init+0x14a/0x280 net/ipv4/ip_tunnel.c:1320
 erspan_tunnel_init+0x116/0x130 net/ipv4/ip_gre.c:1348
 register_netdevice+0x220/0xdd0 net/core/dev.c:10302
 __ip_tunnel_create+0x1c5/0x270 net/ipv4/ip_tunnel.c:266
 ip_tunnel_init_net+0x18a/0x3e0 net/ipv4/ip_tunnel.c:1160
 erspan_init_net+0x35/0x40 net/ipv4/ip_gre.c:1753
 ops_init+0x1ef/0x2b0 net/core/net_namespace.c:139
 setup_net+0x2ea/0x7c0 net/core/net_namespace.c:343
 copy_net_ns+0x37b/0x510 net/core/net_namespace.c:508
 create_new_namespaces+0x228/0x430 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xe6/0x120 kernel/nsproxy.c:228
 ksys_unshare+0x3da/0x720 kernel/fork.c:3323
 __do_sys_unshare kernel/fork.c:3394 [inline]
 __se_sys_unshare kernel/fork.c:3392 [inline]
 __x64_sys_unshare+0x1f/0x30 kernel/fork.c:3392
 x64_sys_call+0x2ca9/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:273
 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: 0x00000060 -> 0x0000005f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4889 Comm: syz-executor.4 Tainted: G        W          6.10.0-rc3-syzkaller-00174-ga3e18a540541 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/07/2024
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