syzbot

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BUG: KCSAN: data-race in pcpu_alloc / pcpu_block_update_hint_alloc

read-write to 0xffffffff86ef831c of 4 bytes by task 3120 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+0x49f/0x4d0 mm/percpu.c:1258
 pcpu_alloc+0x4bd/0x10b0 mm/percpu.c:1808
 __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

read to 0xffffffff86ef831c of 4 bytes by task 3101 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: 0x00000006 -> 0x00000005

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3101 Comm: syz-executor.1 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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