syzbot

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BUG: KCSAN: data-race in pcpu_alloc / pcpu_block_update_hint_alloc

read-write to 0xffffffff86e8f9bc of 4 bytes by task 1835 on cpu 0:
 pcpu_update_empty_pages mm/percpu.c:606 [inline]
 pcpu_block_update_hint_alloc+0x61e/0x6e0 mm/percpu.c:919
 pcpu_alloc_area+0x4dc/0x500 mm/percpu.c:1254
 pcpu_alloc+0x42e/0xfb0 mm/percpu.c:1813
 __alloc_percpu+0x20/0x30 mm/percpu.c:1949
 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+0x1741/0x1ea0 net/ipv4/ip_sockglue.c:1444
 tcp_setsockopt+0x177/0x1be0 net/ipv4/tcp.c:3700
 sock_common_setsockopt+0x5d/0x70 net/core/sock.c:3505
 __sys_setsockopt+0x212/0x2b0 net/socket.c:2212
 __do_sys_setsockopt net/socket.c:2223 [inline]
 __se_sys_setsockopt net/socket.c:2220 [inline]
 __x64_sys_setsockopt+0x62/0x70 net/socket.c:2220
 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+0x46/0xb0

read to 0xffffffff86e8f9bc of 4 bytes by task 15656 on cpu 1:
 pcpu_alloc+0x9bb/0xfb0 mm/percpu.c:1877
 __alloc_percpu_gfp+0x22/0x30 mm/percpu.c:1936
 bpf_map_alloc_percpu+0xab/0x120 kernel/bpf/syscall.c:460
 prealloc_init kernel/bpf/hashtab.c:326 [inline]
 htab_map_alloc+0x76e/0xc00 kernel/bpf/hashtab.c:538
 find_and_alloc_map kernel/bpf/syscall.c:129 [inline]
 map_create+0x38a/0x6e0 kernel/bpf/syscall.c:864
 __sys_bpf+0x269/0x600 kernel/bpf/syscall.c:4645
 __do_sys_bpf kernel/bpf/syscall.c:4767 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:4765 [inline]
 __x64_sys_bpf+0x3f/0x50 kernel/bpf/syscall.c:4765
 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+0x46/0xb0

value changed: 0x00000008 -> 0x00000007

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15656 Comm: syz-executor.1 Not tainted 5.18.0-syzkaller-02752-gfdaf9a5840ac-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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