==================================================================
BUG: KCSAN: data-race in kick_pool / wq_worker_running

read-write to 0xffff888237c29de4 of 4 bytes by task 10 on cpu 0:
 wq_worker_running+0x95/0x120 kernel/workqueue.c:1406
 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:7083
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x467/0xcc0 kernel/locking/mutex.c:760
 __mutex_lock_slowpath+0xa/0x10 kernel/locking/mutex.c:1049
 mutex_lock+0x27/0x30 kernel/locking/mutex.c:274
 pcpu_balance_workfn+0x4a/0xc00 mm/percpu.c:2204
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3346
 worker_thread+0x582/0x770 kernel/workqueue.c:3427
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x122/0x1b0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888237c29de4 of 4 bytes by task 31024 on cpu 1:
 need_more_worker kernel/workqueue.c:940 [inline]
 kick_pool+0x49/0x2d0 kernel/workqueue.c:1246
 __queue_work+0x8cb/0xb50 kernel/workqueue.c:2342
 queue_work_on+0xd1/0x160 kernel/workqueue.c:2392
 queue_work include/linux/workqueue.h:669 [inline]
 schedule_work include/linux/workqueue.h:730 [inline]
 pcpu_schedule_balance_work mm/percpu.c:204 [inline]
 pcpu_alloc_noprof+0x9a7/0x1250 mm/percpu.c:1856
 fib_nh_common_init+0x48/0x260 net/ipv4/fib_semantics.c:620
 fib_nh_init+0x67/0x1a0 net/ipv4/fib_semantics.c:654
 fib_create_info+0xee2/0x1980 net/ipv4/fib_semantics.c:1442
 fib_table_insert+0x60/0xeb0 net/ipv4/fib_trie.c:1212
 fib_magic+0x19a/0x1f0 net/ipv4/fib_frontend.c:1134
 fib_add_ifaddr+0xdb/0x320 net/ipv4/fib_frontend.c:1156
 fib_netdev_event+0x355/0x430 net/ipv4/fib_frontend.c:1516
 notifier_call_chain kernel/notifier.c:85 [inline]
 raw_notifier_call_chain+0x6f/0x1b0 kernel/notifier.c:453
 call_netdevice_notifiers_info+0xae/0x100 net/core/dev.c:2229
 call_netdevice_notifiers_extack net/core/dev.c:2267 [inline]
 call_netdevice_notifiers net/core/dev.c:2281 [inline]
 __dev_notify_flags+0xff/0x1a0 net/core/dev.c:-1
 netif_change_flags+0xac/0xd0 net/core/dev.c:9705
 do_setlink+0x9d2/0x2810 net/core/rtnetlink.c:3151
 rtnl_changelink net/core/rtnetlink.c:3769 [inline]
 __rtnl_newlink net/core/rtnetlink.c:3928 [inline]
 rtnl_newlink+0xe75/0x12d0 net/core/rtnetlink.c:4065
 rtnetlink_rcv_msg+0x5fe/0x6d0 net/core/rtnetlink.c:6954
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2552
 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:6981
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x5c0/0x690 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x58b/0x6b0 net/netlink/af_netlink.c:1896
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x145/0x180 net/socket.c:742
 __sys_sendto+0x268/0x330 net/socket.c:2244
 __do_sys_sendto net/socket.c:2251 [inline]
 __se_sys_sendto net/socket.c:2247 [inline]
 __x64_sys_sendto+0x76/0x90 net/socket.c:2247
 x64_sys_call+0x2d14/0x3000 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 31024 Comm: syz-executor Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================
8021q: adding VLAN 0 to HW filter on device batadv0
veth0_vlan: entered promiscuous mode
veth1_vlan: entered promiscuous mode
veth0_macvtap: entered promiscuous mode
veth1_macvtap: entered promiscuous mode
batman_adv: batadv0: Interface activated: batadv_slave_0
batman_adv: batadv0: Interface activated: batadv_slave_1