netdevsim netdevsim5 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim5 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim5 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim5 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
==================================================================
BUG: KCSAN: data-race in pcpu_alloc / pcpu_balance_workfn

write to 0xffffffff88d27a0c of 4 bytes by task 9168 on cpu 0:
 pcpu_update_empty_pages mm/percpu.c:558 [inline]
 pcpu_chunk_populated mm/percpu.c:1492 [inline]
 __pcpu_balance_workfn mm/percpu.c:2032 [inline]
 pcpu_balance_workfn+0xc7c/0xe40 mm/percpu.c:2068
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2275
 worker_thread+0x616/0xa70 kernel/workqueue.c:2421
 kthread+0x20b/0x230 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

read to 0xffffffff88d27a0c of 4 bytes by task 8430 on cpu 1:
 pcpu_alloc+0xaed/0x1090 mm/percpu.c:1834
 __alloc_percpu_gfp+0x22/0x30 mm/percpu.c:1893
 fib_nh_common_init net/ipv4/fib_semantics.c:580 [inline]
 fib_nh_init+0x75/0x2e0 net/ipv4/fib_semantics.c:619
 fib_create_info+0x1582/0x3090 net/ipv4/fib_semantics.c:1457
 fib_table_insert+0x14a/0x10b0 net/ipv4/fib_trie.c:1189
 fib_magic+0x195/0x1e0 net/ipv4/fib_frontend.c:1085
 fib_add_ifaddr+0x24b/0x300 net/ipv4/fib_frontend.c:1120
 fib_netdev_event+0x178/0x510 net/ipv4/fib_frontend.c:1466
 notifier_call_chain kernel/notifier.c:83 [inline]
 raw_notifier_call_chain+0x53/0xb0 kernel/notifier.c:410
 __dev_notify_flags+0x1d3/0x3a0 net/core/dev.c:2040
 dev_change_flags+0xa2/0xc0 net/core/dev.c:8554
 do_setlink+0x746/0x2260 net/core/rtnetlink.c:2708
 __rtnl_newlink net/core/rtnetlink.c:3376 [inline]
 rtnl_newlink+0xe4e/0x12e0 net/core/rtnetlink.c:3491
 rtnetlink_rcv_msg+0x729/0x7c0 net/core/rtnetlink.c:5553
 netlink_rcv_skb+0x13e/0x240 net/netlink/af_netlink.c:2494
 rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:5571
 netlink_unicast_kernel net/netlink/af_netlink.c:1304 [inline]
 netlink_unicast+0x5fc/0x6c0 net/netlink/af_netlink.c:1330
 netlink_sendmsg+0x6f8/0x7c0 net/netlink/af_netlink.c:1919
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg net/socket.c:672 [inline]
 __sys_sendto+0x2a8/0x370 net/socket.c:1975
 __do_sys_sendto net/socket.c:1987 [inline]
 __se_sys_sendto net/socket.c:1983 [inline]
 __x64_sys_sendto+0x74/0x90 net/socket.c:1983
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8430 Comm: syz-executor.5 Not tainted 5.11.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================