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BUG: KCSAN: data-race in __rcu_read_unlock / rcu_report_exp_cpu_mult

read to 0xffffffff85a7d3c0 of 8 bytes by interrupt on cpu 0:
 rcu_read_unlock_special kernel/rcu/tree_plugin.h:615 [inline]
 __rcu_read_unlock+0x381/0x3c0 kernel/rcu/tree_plugin.h:383
 rcu_read_unlock include/linux/rcupdate.h:652 [inline]
 km_state_notify+0xc2/0xf0 net/xfrm/xfrm_state.c:2136
 km_state_expired net/xfrm/xfrm_state.c:2149 [inline]
 xfrm_timer_handler+0x738/0x7a0 net/xfrm/xfrm_state.c:598
 __run_hrtimer kernel/time/hrtimer.c:1514 [inline]
 __hrtimer_run_queues+0x274/0x5f0 kernel/time/hrtimer.c:1576
 hrtimer_run_softirq+0x10e/0x150 kernel/time/hrtimer.c:1593
 __do_softirq+0x115/0x33f kernel/softirq.c:292
 invoke_softirq kernel/softirq.c:373 [inline]
 irq_exit+0xbb/0xe0 kernel/softirq.c:413
 exiting_irq arch/x86/include/asm/apic.h:536 [inline]
 smp_apic_timer_interrupt+0xe6/0x280 arch/x86/kernel/apic/apic.c:1137
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:830
 arch_local_irq_restore arch/x86/include/asm/paravirt.h:756 [inline]
 slab_alloc_node mm/slab.c:3256 [inline]
 kmem_cache_alloc_node+0xd2/0x660 mm/slab.c:3574
 __alloc_skb+0x8e/0x360 net/core/skbuff.c:197
 alloc_skb include/linux/skbuff.h:1049 [inline]
 __ip6_append_data.isra.0+0x1c9f/0x2070 net/ipv6/ip6_output.c:1518
 ip6_append_data+0x17b/0x250 net/ipv6/ip6_output.c:1687
 rawv6_sendmsg+0xf63/0x21e0 net/ipv6/raw.c:949
 inet_sendmsg+0x6d/0x90 net/ipv4/af_inet.c:807
 sock_sendmsg_nosec net/socket.c:637 [inline]
 sock_sendmsg+0x9f/0xc0 net/socket.c:657
 ___sys_sendmsg+0x2b7/0x5d0 net/socket.c:2311
 __sys_sendmmsg+0x123/0x350 net/socket.c:2413
 __do_sys_sendmmsg net/socket.c:2442 [inline]
 __se_sys_sendmmsg net/socket.c:2439 [inline]
 __x64_sys_sendmmsg+0x64/0x80 net/socket.c:2439
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffffffff85a7d3c0 of 8 bytes by task 14915 on cpu 1:
 rcu_report_exp_cpu_mult+0x4f/0xa0 kernel/rcu/tree_exp.h:244
 sync_rcu_exp_select_node_cpus+0x478/0x510 kernel/rcu/tree_exp.h:414
 sync_rcu_exp_select_cpus+0x30c/0x590 kernel/rcu/tree_exp.h:439
 rcu_exp_sel_wait_wake kernel/rcu/tree_exp.h:575 [inline]
 wait_rcu_exp_gp+0x25/0x40 kernel/rcu/tree_exp.h:589
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14915 Comm: kworker/1:1 Not tainted 5.4.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: rcu_gp wait_rcu_exp_gp
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