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BUG: KCSAN: data-race in pcpu_alloc / pcpu_chunk_populated

write to 0xffffffff860478c0 of 4 bytes by task 5 on cpu 0:
 pcpu_update_empty_pages mm/percpu.c:575 [inline]
 pcpu_chunk_populated+0xed/0x110 mm/percpu.c:1483
 pcpu_balance_workfn+0xa3c/0xc80 mm/percpu.c:1921
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269
 worker_thread+0xa0/0x800 kernel/workqueue.c:2415
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffffffff860478c0 of 4 bytes by task 8128 on cpu 1:
 pcpu_alloc+0x3b0/0xcf0 mm/percpu.c:1729
 __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:3157 [inline]
 tcp_setsockopt+0x7c/0xc0 net/ipv4/tcp.c:3151
 sock_common_setsockopt+0x67/0x90 net/core/sock.c:3151
 __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
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8128 Comm: syz-executor.4 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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