syzbot

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BUG: KCSAN: data-race in pcpu_alloc / pcpu_alloc

read-write to 0xffffffff86eea29c of 4 bytes by task 3102 on cpu 1:
 pcpu_update_empty_pages mm/percpu.c:602 [inline]
 pcpu_chunk_populated mm/percpu.c:1531 [inline]
 pcpu_alloc+0xa1f/0x12a0 mm/percpu.c:1863
 __alloc_percpu+0x24/0x30 mm/percpu.c:1945
 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
 ipt_register_table+0x9a/0x430 net/ipv4/netfilter/ip_tables.c:1734
 iptable_raw_table_init+0x77/0xa0 net/ipv4/netfilter/iptable_raw.c:49
 xt_find_table_lock+0x190/0x260 net/netfilter/x_tables.c:1259
 xt_request_find_table_lock+0x26/0xa0 net/netfilter/x_tables.c:1284
 get_info net/ipv4/netfilter/ip_tables.c:963 [inline]
 do_ipt_get_ctl+0x552/0xbe0 net/ipv4/netfilter/ip_tables.c:1651
 nf_getsockopt+0x184/0x1a0 net/netfilter/nf_sockopt.c:116
 ip_getsockopt+0x126/0x170 net/ipv4/ip_sockglue.c:1788
 tcp_getsockopt+0xa7/0xd0 net/ipv4/tcp.c:4280
 sock_common_getsockopt+0x57/0x70 net/core/sock.c:3672
 __sys_getsockopt+0x175/0x1d0 net/socket.c:2371
 __do_sys_getsockopt net/socket.c:2386 [inline]
 __se_sys_getsockopt net/socket.c:2383 [inline]
 __x64_sys_getsockopt+0x66/0x80 net/socket.c:2383
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff86eea29c of 4 bytes by task 903 on cpu 0:
 pcpu_alloc+0xa59/0x12a0 mm/percpu.c:1870
 __alloc_percpu_gfp+0x26/0x30 mm/percpu.c:1932
 fib_nh_common_init+0x48/0x2b0 net/ipv4/fib_semantics.c:591
 fib6_nh_init+0xdbd/0x15c0 net/ipv6/route.c:3610
 ip6_route_info_create+0x799/0xb60 net/ipv6/route.c:3799
 ip6_route_add+0x26/0x100 net/ipv6/route.c:3843
 addrconf_prefix_route net/ipv6/addrconf.c:2434 [inline]
 addrconf_add_linklocal+0x29b/0x380 net/ipv6/addrconf.c:3254
 addrconf_addr_gen+0x27d/0x460 net/ipv6/addrconf.c:3383
 addrconf_init_auto_addrs+0x7e4/0x9a0
 addrconf_notify+0x7da/0x980 net/ipv6/addrconf.c:3679
 notifier_call_chain kernel/notifier.c:93 [inline]
 raw_notifier_call_chain+0x6b/0x1c0 kernel/notifier.c:461
 call_netdevice_notifiers_info net/core/dev.c:1995 [inline]
 netdev_state_change+0x103/0x180 net/core/dev.c:1377
 linkwatch_do_dev+0xb3/0xe0 net/core/link_watch.c:182
 __linkwatch_run_queue+0x284/0x510 net/core/link_watch.c:235
 linkwatch_event+0x40/0x50 net/core/link_watch.c:278
 process_one_work kernel/workqueue.c:2630 [inline]
 process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
 worker_thread+0x525/0x730 kernel/workqueue.c:2784
 kthread+0x1d7/0x210 kernel/kthread.c:388
 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

value changed: 0xffffffff -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 903 Comm: kworker/0:2 Not tainted 6.6.0-rc7-syzkaller-00123-g3a568e3a961b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Workqueue: events linkwatch_event
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