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BUG: KCSAN: data-race in pcpu_alloc / pcpu_balance_workfn

read-write to 0xffffffff870d7b74 of 4 bytes by task 1925 on cpu 1:
 pcpu_update_empty_pages mm/percpu.c:606 [inline]
 pcpu_chunk_populated mm/percpu.c:1534 [inline]
 pcpu_balance_populated mm/percpu.c:2095 [inline]
 pcpu_balance_workfn+0xa58/0xb90 mm/percpu.c:2246
 process_one_work+0x3d3/0x720 kernel/workqueue.c:2289
 worker_thread+0x618/0xa70 kernel/workqueue.c:2436
 kthread+0x1a9/0x1e0 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306

read to 0xffffffff870d7b74 of 4 bytes by task 1825 on cpu 0:
 pcpu_alloc+0x91d/0xf60 mm/percpu.c:1877
 __alloc_percpu+0x20/0x30 mm/percpu.c:1950
 xt_percpu_counter_alloc+0x6e/0x110 net/netfilter/x_tables.c:1930
 find_check_entry net/ipv4/netfilter/ip_tables.c:528 [inline]
 translate_table+0x96c/0xfb0 net/ipv4/netfilter/ip_tables.c:718
 do_replace net/ipv4/netfilter/ip_tables.c:1136 [inline]
 do_ipt_set_ctl+0x13d7/0x16e0 net/ipv4/netfilter/ip_tables.c:1630
 nf_setsockopt+0x1a6/0x1c0 net/netfilter/nf_sockopt.c:101
 ip_setsockopt+0xe2/0x100 net/ipv4/ip_sockglue.c:1444
 tcp_setsockopt+0x8c/0xa0 net/ipv4/tcp.c:3800
 sock_common_setsockopt+0x5d/0x70 net/core/sock.c:3641
 __sys_setsockopt+0x212/0x2b0 net/socket.c:2252
 __do_sys_setsockopt net/socket.c:2263 [inline]
 __se_sys_setsockopt net/socket.c:2260 [inline]
 __x64_sys_setsockopt+0x62/0x70 net/socket.c:2260
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000001 -> 0x00000004

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1825 Comm: syz-executor.3 Not tainted 6.1.0-syzkaller-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
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