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BUG: KCSAN: data-race in rcu_gp_fqs_check_wake / rcu_preempt_deferred_qs_irqrestore

write to 0xffffffff85a7d490 of 8 bytes by task 7217 on cpu 1:
 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/0x3c0 kernel/rcu/tree_plugin.h:383
 rcu_read_unlock include/linux/rcupdate.h:652 [inline]
 batadv_hardif_get_by_netdev+0xd2/0x100 net/batman-adv/hard-interface.c:79
 batadv_hard_if_event+0xb0/0x880 net/batman-adv/hard-interface.c:1029
 notifier_call_chain+0xd7/0x160 kernel/notifier.c:95
 __raw_notifier_call_chain kernel/notifier.c:396 [inline]
 raw_notifier_call_chain+0x37/0x50 kernel/notifier.c:403
 call_netdevice_notifiers_info+0x48/0xc0 net/core/dev.c:1749
 __netdev_upper_dev_link+0x23e/0x310 net/core/dev.c:7128
 netdev_master_upper_dev_link+0x43/0x60 net/core/dev.c:7181
 br_add_if+0x5ed/0xdb0 net/bridge/br_if.c:625
 br_add_slave+0x32/0x50 net/bridge/br_device.c:365
 do_set_master net/core/rtnetlink.c:2369 [inline]
 do_set_master+0x14e/0x170 net/core/rtnetlink.c:2343
 do_setlink+0x673/0x1e30 net/core/rtnetlink.c:2504
 __rtnl_newlink+0x93e/0x1010 net/core/rtnetlink.c:3129

read to 0xffffffff85a7d490 of 8 bytes by task 10 on cpu 0:
 rcu_gp_fqs_check_wake kernel/rcu/tree.c:1584 [inline]
 rcu_gp_fqs_check_wake+0x93/0xd0 kernel/rcu/tree.c:1574
 rcu_gp_fqs_loop+0x36c/0x580 kernel/rcu/tree.c:1639
 rcu_gp_kthread+0x143/0x230 kernel/rcu/tree.c:1799
 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 5.4.0-rc3+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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