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BUG: KCSAN: data-race in rcu_gp_fqs_check_wake / rcu_preempt_deferred_qs_irqrestore

write to 0xffffffff85a7d1d0 of 8 bytes by task 8428 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]
 inet_twsk_purge+0x259/0x2d0 net/ipv4/inet_timewait_sock.c:299
 dccp_v4_exit_batch+0x23/0x30 net/dccp/ipv4.c:1030
 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:2269
 worker_thread+0xa0/0x800 kernel/workqueue.c:2415
 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352

read to 0xffffffff85a7d1d0 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-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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