syzbot

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BUG: KCSAN: data-race in pcpu_alloc / pcpu_free_area

read-write to 0xffffffff86ef831c of 4 bytes by task 3104 on cpu 0:
 pcpu_update_empty_pages mm/percpu.c:602 [inline]
 pcpu_block_update_hint_free mm/percpu.c:1044 [inline]
 pcpu_free_area+0x4e2/0x570 mm/percpu.c:1302
 free_percpu+0x1c6/0xb20 mm/percpu.c:2303
 xt_percpu_counter_free+0x63/0x70 net/netfilter/x_tables.c:1950
 cleanup_entry+0x17b/0x1a0 net/ipv4/netfilter/ip_tables.c:654
 __do_replace+0x46a/0x570 net/ipv4/netfilter/ip_tables.c:1082
 do_replace net/ipv4/netfilter/ip_tables.c:1137 [inline]
 do_ipt_set_ctl+0x1440/0x1730 net/ipv4/netfilter/ip_tables.c:1627
 nf_setsockopt+0x18d/0x1b0 net/netfilter/nf_sockopt.c:101
 ip_setsockopt+0xe6/0x100 net/ipv4/ip_sockglue.c:1426
 tcp_setsockopt+0x90/0xa0 net/ipv4/tcp.c:3704
 sock_common_setsockopt+0x61/0x70 net/core/sock.c:3711
 do_sock_setsockopt net/socket.c:2311 [inline]
 __sys_setsockopt+0x1d4/0x240 net/socket.c:2334
 __do_sys_setsockopt net/socket.c:2343 [inline]
 __se_sys_setsockopt net/socket.c:2340 [inline]
 __x64_sys_setsockopt+0x66/0x80 net/socket.c:2340
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffffffff86ef831c of 4 bytes by task 3111 on cpu 1:
 pcpu_alloc+0x9bc/0x10b0 mm/percpu.c:1868
 __alloc_percpu+0x24/0x30 mm/percpu.c:1943
 xt_percpu_counter_alloc+0x72/0x110 net/netfilter/x_tables.c:1930
 find_check_entry net/ipv4/netfilter/ip_tables.c:526 [inline]
 translate_table+0x90b/0xf60 net/ipv4/netfilter/ip_tables.c:716
 do_replace net/ipv4/netfilter/ip_tables.c:1133 [inline]
 do_ipt_set_ctl+0x13f0/0x1730 net/ipv4/netfilter/ip_tables.c:1627
 nf_setsockopt+0x18d/0x1b0 net/netfilter/nf_sockopt.c:101
 ip_setsockopt+0xe6/0x100 net/ipv4/ip_sockglue.c:1426
 tcp_setsockopt+0x90/0xa0 net/ipv4/tcp.c:3704
 sock_common_setsockopt+0x61/0x70 net/core/sock.c:3711
 do_sock_setsockopt net/socket.c:2311 [inline]
 __sys_setsockopt+0x1d4/0x240 net/socket.c:2334
 __do_sys_setsockopt net/socket.c:2343 [inline]
 __se_sys_setsockopt net/socket.c:2340 [inline]
 __x64_sys_setsockopt+0x66/0x80 net/socket.c:2340
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000005 -> 0x00000006

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3111 Comm: syz-executor.2 Not tainted 6.7.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
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