syzbot

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BUG: KCSAN: data-race in pcpu_alloc / pcpu_block_update_hint_alloc

read-write to 0xffffffff86efe674 of 4 bytes by task 3126 on cpu 1:
 pcpu_update_empty_pages mm/percpu.c:602 [inline]
 pcpu_block_update_hint_alloc+0x61a/0x6e0 mm/percpu.c:923
 pcpu_alloc_area+0x4c0/0x4f0 mm/percpu.c:1258
 pcpu_alloc+0x42e/0xf60 mm/percpu.c:1810
 __alloc_percpu+0x20/0x30 mm/percpu.c:1943
 xt_percpu_counter_alloc+0x6e/0x110 net/netfilter/x_tables.c:1930
 find_check_entry net/ipv6/netfilter/ip6_tables.c:547 [inline]
 translate_table+0x9ff/0x1090 net/ipv6/netfilter/ip6_tables.c:735
 do_replace net/ipv6/netfilter/ip6_tables.c:1153 [inline]
 do_ip6t_set_ctl+0x1468/0x1790 net/ipv6/netfilter/ip6_tables.c:1639
 nf_setsockopt+0x1a6/0x1c0 net/netfilter/nf_sockopt.c:101
 ipv6_setsockopt+0x118/0x130 net/ipv6/ipv6_sockglue.c:1028
 tcp_setsockopt+0x8c/0xa0 net/ipv4/tcp.c:3801
 sock_common_setsockopt+0x5d/0x70 net/core/sock.c:3663
 __sys_setsockopt+0x1c8/0x230 net/socket.c:2246
 __do_sys_setsockopt net/socket.c:2257 [inline]
 __se_sys_setsockopt net/socket.c:2254 [inline]
 __x64_sys_setsockopt+0x62/0x70 net/socket.c:2254
 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

read to 0xffffffff86efe674 of 4 bytes by task 3119 on cpu 0:
 pcpu_alloc+0x91d/0xf60 mm/percpu.c:1870
 __alloc_percpu+0x20/0x30 mm/percpu.c:1943
 xt_percpu_counter_alloc+0x6e/0x110 net/netfilter/x_tables.c:1930
 find_check_entry net/ipv6/netfilter/ip6_tables.c:547 [inline]
 translate_table+0x9ff/0x1090 net/ipv6/netfilter/ip6_tables.c:735
 do_replace net/ipv6/netfilter/ip6_tables.c:1153 [inline]
 do_ip6t_set_ctl+0x1468/0x1790 net/ipv6/netfilter/ip6_tables.c:1639
 nf_setsockopt+0x1a6/0x1c0 net/netfilter/nf_sockopt.c:101
 ipv6_setsockopt+0x118/0x130 net/ipv6/ipv6_sockglue.c:1028
 tcp_setsockopt+0x8c/0xa0 net/ipv4/tcp.c:3801
 sock_common_setsockopt+0x5d/0x70 net/core/sock.c:3663
 __sys_setsockopt+0x1c8/0x230 net/socket.c:2246
 __do_sys_setsockopt net/socket.c:2257 [inline]
 __se_sys_setsockopt net/socket.c:2254 [inline]
 __x64_sys_setsockopt+0x62/0x70 net/socket.c:2254
 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: 0x00000004 -> 0x00000003

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3119 Comm: syz-executor.2 Not tainted 6.1.0-syzkaller-13139-gf9ff5644bcc0-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
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