==================================================================
BUG: KCSAN: data-race in rcu_gp_fqs_check_wake / rcu_note_context_switch

write to 0xffffffff85c7d0d0 of 8 bytes by task 21 on cpu 1:
 rcu_preempt_ctxt_queue kernel/rcu/tree_plugin.h:223 [inline]
 rcu_note_context_switch+0x6f6/0x760 kernel/rcu/tree_plugin.h:315
 __schedule+0xa4/0x690 kernel/sched/core.c:4019
 preempt_schedule_common+0x37/0x90 kernel/sched/core.c:4236
 preempt_schedule+0x30/0x40 kernel/sched/core.c:4261
 ___preempt_schedule+0x16/0x18 arch/x86/entry/thunk_64.S:50
 __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:169 [inline]
 _raw_spin_unlock_irq+0x74/0x80 kernel/locking/spinlock.c:199
 spin_unlock_irq include/linux/spinlock.h:388 [inline]
 start_flush_work kernel/workqueue.c:3001 [inline]
 __flush_work+0x216/0x390 kernel/workqueue.c:3040
 flush_work+0x21/0x30 kernel/workqueue.c:3062
 flush_all_backlogs net/core/dev.c:5489 [inline]
 rollback_registered_many+0x403/0xa40 net/core/dev.c:8729
 unregister_netdevice_many net/core/dev.c:9907 [inline]
 unregister_netdevice_many+0x62/0x240 net/core/dev.c:9902
 ip_tunnel_delete_nets+0x239/0x270 net/ipv4/ip_tunnel.c:1113
 vti_exit_batch_net+0x38/0x50 net/ipv4/ip_vti.c:474
 ops_exit_list.isra.0+0xa2/0xc0 net/core/net_namespace.c:175
 cleanup_net+0x405/0x6b0 net/core/net_namespace.c:597
 process_one_work+0x3d4/0x890 kernel/workqueue.c:2264
 worker_thread+0xa0/0x800 kernel/workqueue.c:2410
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffffffff85c7d0d0 of 8 bytes by task 10 on cpu 0:
 rcu_gp_fqs_check_wake kernel/rcu/tree.c:1606 [inline]
 rcu_gp_fqs_check_wake+0x93/0xd0 kernel/rcu/tree.c:1596
 rcu_gp_fqs_loop+0x1df/0x580 kernel/rcu/tree.c:1661
 rcu_gp_kthread+0x143/0x230 kernel/rcu/tree.c:1821
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 10 Comm: rcu_preempt Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================