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BUG: KCSAN: data-race in pcpu_alloc / pcpu_block_update_hint_alloc

read-write to 0xffffffff883da4dc of 4 bytes by task 28881 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+0x4b3/0x10d0 mm/percpu.c:1808
 __alloc_percpu+0x24/0x30 mm/percpu.c:1943
 xt_percpu_counter_alloc+0x72/0x110 net/netfilter/x_tables.c:1931
 find_check_entry net/ipv4/netfilter/ip_tables.c:526 [inline]
 translate_table+0x921/0xf70 net/ipv4/netfilter/ip_tables.c:716
 do_replace net/ipv4/netfilter/ip_tables.c:1133 [inline]
 do_ipt_set_ctl+0x13fc/0x1740 net/ipv4/netfilter/ip_tables.c:1627
 nf_setsockopt+0x195/0x1b0 net/netfilter/nf_sockopt.c:101
 ip_setsockopt+0xea/0x100 net/ipv4/ip_sockglue.c:1424
 tcp_setsockopt+0x93/0xb0 net/ipv4/tcp.c:3735
 sock_common_setsockopt+0x64/0x80 net/core/sock.c:3727
 do_sock_setsockopt net/socket.c:2311 [inline]
 __sys_setsockopt+0x1d8/0x250 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_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

read to 0xffffffff883da4dc of 4 bytes by task 11160 on cpu 1:
 pcpu_alloc+0x9aa/0x10d0 mm/percpu.c:1868
 __alloc_percpu+0x24/0x30 mm/percpu.c:1943
 alloc_vfsmnt+0xf7/0x300 fs/namespace.c:220
 clone_mnt+0x45/0x790 fs/namespace.c:1186
 copy_tree+0x2e5/0x800 fs/namespace.c:2015
 copy_mnt_ns+0x11e/0x5c0 fs/namespace.c:3788
 create_new_namespaces+0x89/0x430 kernel/nsproxy.c:78
 copy_namespaces+0x1ad/0x210 kernel/nsproxy.c:179
 copy_process+0xf08/0x1f80 kernel/fork.c:2392
 kernel_clone+0x16a/0x570 kernel/fork.c:2796
 __do_sys_clone kernel/fork.c:2939 [inline]
 __se_sys_clone kernel/fork.c:2923 [inline]
 __x64_sys_clone+0xe8/0x120 kernel/fork.c:2923
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

value changed: 0x00000096 -> 0x00000095

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11160 Comm: syz-executor.0 Not tainted 6.9.0-rc1-syzkaller-00011-g498e47cd1d1f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024
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