rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (10500 ticks this GP) idle=dbe/1/0x4000000000000002 softirq=23914/23914 fqs=5249 
	(t=10502 jiffies g=19105 q=2014)
NMI backtrace for cpu 0
CPU: 0 PID: 11340 Comm: syz-executor.4 Not tainted 5.6.0-rc1-next-20200212-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:164 [inline]
 rcu_dump_cpu_stacks+0x183/0x1cf 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:3030 [inline]
 rcu_sched_clock_irq.cold+0x51a/0xc3d kernel/rcu/tree.c:2276
 update_process_times+0x2d/0x70 kernel/time/timer.c:1726
 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:__sanitizer_cov_trace_pc+0x4b/0x50 kernel/kcov.c:197
Code: 90 88 13 00 00 83 fa 02 75 20 48 8b 88 90 13 00 00 8b 80 8c 13 00 00 48 8b 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 <5d> c3 0f 1f 00 65 4c 8b 04 25 c0 1e 02 00 65 8b 05 88 50 8c 7e a9
RSP: 0018:ffffc90001ac70d0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
RAX: 0000000000040000 RBX: 0000000000000ef8 RCX: ffffc900132ed000
RDX: 0000000000040000 RSI: ffffffff818ec400 RDI: ffff88809630b010
RBP: ffffc90001ac70d0 R08: ffff8880952dc240 R09: ffffed1011b4d423
R10: ffffed1011b4d422 R11: ffff88808da6a117 R12: 0000000000000010
R13: dffffc0000000000 R14: ffff88809630b000 R15: ffffc90001ac7448
 perf_output_read_group kernel/events/core.c:6513 [inline]
 perf_output_read+0xc50/0x1390 kernel/events/core.c:6553
 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:ffffc90001ac7a00 EFLAGS: 00010206
RAX: 0000000000000001 RBX: 0000000000008000 RCX: 0000000000001fcb
RDX: 0000000000008000 RSI: 0000000020fd3000 RDI: ffff88804dfbe035
RBP: ffffc90001ac7a38 R08: ffffed1009bf8000 R09: 0000000000000000
R10: ffffed1009bf7fff R11: ffff88804dfbffff R12: 0000000020fccfcb
R13: ffff88804dfb8000 R14: 0000000020fd4fcb R15: 00007ffffffff000
 _copy_from_iter_full+0x20b/0x870 lib/iov_iter.c:789
 copy_from_iter_full include/linux/uio.h:156 [inline]
 skb_do_copy_data_nocache include/net/sock.h:1977 [inline]
 skb_copy_to_page_nocache include/net/sock.h:2003 [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:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45b3b9
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:00007f554200ac78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f554200b6d4 RCX: 000000000045b3b9
RDX: ffffffffffffffef RSI: 0000000020d7cfcb RDI: 0000000000000006
RBP: 000000000075bf20 R08: 0000000000000000 R09: 0f0000000000e803
R10: 00000000000001f4 R11: 0000000000000246 R12: 00000000ffffffff
R13: 00000000000009d5 R14: 00000000004cb467 R15: 000000000075bf2c