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

write to 0xffffffff85c7d0d0 of 8 bytes by task 20202 on cpu 0:
 rcu_preempt_deferred_qs_irqrestore+0x43d/0x580 kernel/rcu/tree_plugin.h:496
 rcu_read_unlock_special kernel/rcu/tree_plugin.h:644 [inline]
 __rcu_read_unlock+0x16a/0x3d0 kernel/rcu/tree_plugin.h:383
 rcu_read_unlock include/linux/rcupdate.h:670 [inline]
 start_flush_work kernel/workqueue.c:3017 [inline]
 __flush_work+0x21b/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
 rtnl_delete_link+0x98/0xd0 net/core/rtnetlink.c:2928
 rtnl_dellink+0x1f3/0x690 net/core/rtnetlink.c:2980
 rtnetlink_rcv_msg+0x1d3/0x500 net/core/rtnetlink.c:5424
 netlink_rcv_skb+0xb0/0x260 net/netlink/af_netlink.c:2477
 rtnetlink_rcv+0x26/0x30 net/core/rtnetlink.c:5442
 netlink_unicast_kernel net/netlink/af_netlink.c:1302 [inline]
 netlink_unicast+0x3a6/0x4d0 net/netlink/af_netlink.c:1328
 netlink_sendmsg+0x4d3/0x8b0 net/netlink/af_netlink.c:1917
 sock_sendmsg_nosec net/socket.c:639 [inline]
 sock_sendmsg+0x9f/0xc0 net/socket.c:659
 ____sys_sendmsg+0x49d/0x4d0 net/socket.c:2330
 ___sys_sendmsg+0xb5/0x100 net/socket.c:2384
 __sys_sendmsg+0xa0/0x160 net/socket.c:2417
 __do_sys_sendmsg net/socket.c:2426 [inline]
 __se_sys_sendmsg net/socket.c:2424 [inline]
 __x64_sys_sendmsg+0x51/0x70 net/socket.c:2424
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffffffff85c7d0d0 of 8 bytes by task 10 on cpu 1:
 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+0x36c/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: 1 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
==================================================================