rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (1 GPs behind) idle=756/1/0x4000000000000002 softirq=45773/45774 fqs=5234 
	(t=10502 jiffies g=77737 q=1731)
NMI backtrace for cpu 0
CPU: 0 PID: 22074 Comm: syz-executor.0 Not tainted 5.6.0-rc2-next-20200224-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x197/0x210 lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
 trigger_single_cpu_backtrace include/linux/nmi.h:165 [inline]
 rcu_dump_cpu_stacks+0x1a2/0x1ef kernel/rcu/tree_stall.h:254
 print_cpu_stall kernel/rcu/tree_stall.h:475 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:549 [inline]
 rcu_pending kernel/rcu/tree.c:3226 [inline]
 rcu_sched_clock_irq.cold+0x570/0xcc2 kernel/rcu/tree.c:2297
 update_process_times+0x2d/0x70 kernel/time/timer.c:1727
 tick_sched_handle+0xa2/0x190 kernel/time/tick-sched.c:171
 tick_sched_timer+0x53/0x140 kernel/time/tick-sched.c:1314
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x364/0xe40 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x314/0x770 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline]
 smp_apic_timer_interrupt+0x160/0x610 arch/x86/kernel/apic/apic.c:1144
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:perf_output_read_group kernel/events/core.c:6518 [inline]
RIP: 0010:perf_output_read+0xd42/0x1390 kernel/events/core.c:6553
Code: f8 48 c1 e8 03 42 80 3c 28 00 0f 85 2c 05 00 00 49 8d be b0 04 00 00 49 8b 9e d0 02 00 00 48 89 f8 48 c1 e8 03 42 80 3c 28 00 <0f> 85 16 05 00 00 48 85 db 4d 8b a6 b0 04 00 00 74 25 e8 67 0e e7
RSP: 0018:ffffc900034d70e0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 1ffff1100a92d496 RBX: 0000000000000000 RCX: ffffc90002151000
RDX: 0000000000040000 RSI: ffffffff818ed5ef RDI: ffff88805496a4b0
RBP: ffffc900034d72c8 R08: ffff888099f18180 R09: ffffed100a92d418
R10: ffffed100a92d417 R11: ffff88805496a0bf R12: ffff88805496a0b8
R13: dffffc0000000000 R14: ffff88805496a000 R15: ffffc900034d7448
 perf_output_sample+0x1602/0x1dc0 kernel/events/core.c:6600
 __perf_event_output kernel/events/core.c:6965 [inline]
 perf_event_output_forward+0x150/0x280 kernel/events/core.c:6979
 __perf_event_overflow+0x141/0x370 kernel/events/core.c:8446
 perf_swevent_overflow+0xaa/0x140 kernel/events/core.c:8522
 perf_swevent_event+0x1f7/0x2f0 kernel/events/core.c:8555
 do_perf_sw_event kernel/events/core.c:8663 [inline]
 ___perf_sw_event+0x31c/0x570 kernel/events/core.c:8694
 __perf_sw_event+0x51/0xa0 kernel/events/core.c:8706
 perf_sw_event include/linux/perf_event.h:1150 [inline]
 do_user_addr_fault arch/x86/mm/fault.c:1505 [inline]
 do_page_fault+0xa98/0x12e1 arch/x86/mm/fault.c:1539
 page_fault+0x39/0x40 arch/x86/entry/entry_64.S:1203
RIP: 0010:copy_user_enhanced_fast_string+0xe/0x30 arch/x86/lib/copy_user_64.S:205
Code: 89 d1 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 31 c0 0f 1f 00 c3 0f 1f 80 00 00 00 00 0f 1f 00 83 fa 40 0f 82 70 ff ff ff 89 d1 <f3> a4 31 c0 0f 1f 00 c3 66 2e 0f 1f 84 00 00 00 00 00 89 d1 f3 a4
RSP: 0018:ffffc900034d7a00 EFLAGS: 00010206
RAX: 0000000000000001 RBX: 0000000000008000 RCX: 0000000000000fcb
RDX: 0000000000008000 RSI: 0000000020fec000 RDI: ffff88805452f035
RBP: ffffc900034d7a38 R08: ffffed100a8a6000 R09: 0000000000000000
R10: ffffed100a8a5fff R11: ffff88805452ffff R12: 0000000020fe4fcb
R13: ffff888054528000 R14: 0000000020fecfcb R15: 00007ffffffff000
 _copy_from_iter_full+0x20b/0x870 lib/iov_iter.c:790
 copy_from_iter_full include/linux/uio.h:156 [inline]
 skb_do_copy_data_nocache include/net/sock.h:2035 [inline]
 skb_copy_to_page_nocache include/net/sock.h:2061 [inline]
 tcp_sendmsg_locked+0x13bb/0x3470 net/ipv4/tcp.c:1335
 tcp_sendmsg+0x30/0x50 net/ipv4/tcp.c:1433
 inet_sendmsg+0x9e/0xe0 net/ipv4/af_inet.c:807
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xd7/0x130 net/socket.c:672
 __sys_sendto+0x262/0x380 net/socket.c:1998
 __do_sys_sendto net/socket.c:2010 [inline]
 __se_sys_sendto net/socket.c:2006 [inline]
 __x64_sys_sendto+0xe1/0x1a0 net/socket.c:2006
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c449
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fb2c9021c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007fb2c90226d4 RCX: 000000000045c449
RDX: ffffffffffffffef RSI: 0000000020d7cfcb RDI: 0000000000000007
RBP: 000000000076bf20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000a03 R14: 00000000004cc784 R15: 000000000076bf2c