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

read-write to 0xffff888237c2a8e4 of 4 bytes by task 3384 on cpu 0:
 wq_worker_running+0x9b/0x120 kernel/workqueue.c:1434
 schedule_preempt_disabled+0x10/0x20 kernel/sched/core.c:7383
 __mutex_lock_common kernel/locking/mutex.c:726 [inline]
 __mutex_lock+0x524/0xf40 kernel/locking/mutex.c:821
 __mutex_lock_slowpath+0xa/0x10 kernel/locking/mutex.c:1164
 mutex_lock+0x88/0x90 kernel/locking/mutex.c:319
 rtnl_lock+0x15/0x20 net/core/rtnetlink.c:80
 switchdev_deferred_process_work+0xe/0x20 net/switchdev/switchdev.c:104
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0x4d4/0x9a0 kernel/workqueue.c:3405
 worker_thread+0x569/0x750 kernel/workqueue.c:3486
 kthread+0x221/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff888237c2a8e4 of 4 bytes by task 13810 on cpu 1:
 need_more_worker kernel/workqueue.c:952 [inline]
 kick_pool+0x49/0x2d0 kernel/workqueue.c:1274
 __queue_work+0x8e9/0xb90 kernel/workqueue.c:2402
 queue_work_on+0xa9/0x140 kernel/workqueue.c:2452
 queue_work include/linux/workqueue.h:699 [inline]
 schedule_work include/linux/workqueue.h:760 [inline]
 netdev_work_enqueue+0x1b0/0x1f0 net/core/netdev_work.c:42
 __netdev_work_core_sched+0x1f/0x30 net/core/netdev_work.c:93
 netif_rx_mode_queue net/core/dev_addr_lists.c:1337 [inline]
 __dev_set_rx_mode+0x12f/0x220 net/core/dev_addr_lists.c:1376
 __dev_mc_add net/core/dev_addr_lists.c:1002 [inline]
 dev_mc_add+0x8d/0xb0 net/core/dev_addr_lists.c:1016
 igmp6_group_added+0xfc/0x320 net/ipv6/mcast.c:681
 __ipv6_dev_mc_inc+0x4e1/0x5c0 net/ipv6/mcast.c:972
 ipv6_dev_mc_inc+0x1f/0x30 net/ipv6/mcast.c:981
 addrconf_join_solict net/ipv6/addrconf.c:2262 [inline]
 addrconf_dad_begin net/ipv6/addrconf.c:4134 [inline]
 addrconf_dad_work+0x26a/0xbc0 net/ipv6/addrconf.c:4262
 process_one_work kernel/workqueue.c:3322 [inline]
 process_scheduled_works+0x4d4/0x9a0 kernel/workqueue.c:3405
 worker_thread+0x569/0x750 kernel/workqueue.c:3486
 kthread+0x221/0x270 kernel/kthread.c:436
 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 13810 Comm: kworker/u8:6 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Workqueue: ipv6_addrconf addrconf_dad_work
==================================================================
bond2: (slave ip6gretap1): failed to get link speed/duplex
bond2: (slave ip6gretap1): failed to get link speed/duplex
bond2: (slave ip6gretap1): failed to get link speed/duplex
bond2: (slave ip6gretap1): failed to get link speed/duplex