rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	1-....: (10500 ticks this GP) idle=b02/1/0x4000000000000002 softirq=20412/20412 fqs=5246 
	(t=10502 jiffies g=28653 q=1325)
NMI backtrace for cpu 1
CPU: 1 PID: 12628 Comm: syz-executor.2 Not tainted 5.6.0-rc3-next-20200228-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+0x188/0x20d lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x70/0xb1 lib/nmi_backtrace.c:101
 nmi_trigger_cpumask_backtrace+0x231/0x27e lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:165 [inline]
 rcu_dump_cpu_stacks+0x19e/0x1e8 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:3237 [inline]
 rcu_sched_clock_irq.cold+0x560/0xcfa kernel/rcu/tree.c:2308
 update_process_times+0x25/0x60 kernel/time/timer.c:1727
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:171
 tick_sched_timer+0x4e/0x140 kernel/time/tick-sched.c:1314
 __run_hrtimer kernel/time/hrtimer.c:1517 [inline]
 __hrtimer_run_queues+0x32c/0xdd0 kernel/time/hrtimer.c:1579
 hrtimer_interrupt+0x312/0x770 kernel/time/hrtimer.c:1641
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1119 [inline]
 smp_apic_timer_interrupt+0x15b/0x600 arch/x86/kernel/apic/apic.c:1144
 apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:829
 </IRQ>
RIP: 0010:check_kcov_mode kernel/kcov.c:153 [inline]
RIP: 0010:write_comp_data+0x10/0x70 kernel/kcov.c:208
Code: 11 48 83 c2 01 48 39 d0 76 07 48 89 34 d1 48 89 11 c3 0f 1f 84 00 00 00 00 00 65 4c 8b 04 25 c0 1e 02 00 65 8b 05 a8 88 8f 7e <a9> 00 01 1f 00 75 51 41 8b 80 88 13 00 00 83 f8 03 75 45 49 8b 80
RSP: 0018:ffffc90002407138 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13
RAX: 0000000000000002 RBX: 0000000000000010 RCX: ffffffff818acd47
RDX: 0000000000000810 RSI: 0000000000000000 RDI: 0000000000000007
RBP: 0000000000000820 R08: ffff888093ef0300 R09: ffffed10151a2efe
R10: ffffed10151a2efd R11: ffff8880a8d177ef R12: dffffc0000000000
R13: ffffc90002407498 R14: ffffc90002407298 R15: ffff8880943a0000
 __output_copy kernel/events/internal.h:178 [inline]
 perf_output_read_group kernel/events/core.c:6521 [inline]
 perf_output_read+0xd47/0x11f0 kernel/events/core.c:6554
 perf_output_sample+0x14f5/0x1be0 kernel/events/core.c:6601
 __perf_event_output kernel/events/core.c:6966 [inline]
 perf_event_output_forward+0x12f/0x270 kernel/events/core.c:6980
 __perf_event_overflow+0x13c/0x370 kernel/events/core.c:8447
 perf_swevent_overflow+0xac/0x150 kernel/events/core.c:8523
 perf_swevent_event+0x1e9/0x2e0 kernel/events/core.c:8556
 do_perf_sw_event kernel/events/core.c:8664 [inline]
 ___perf_sw_event+0x31c/0x570 kernel/events/core.c:8695
 __perf_sw_event+0x4b/0xa0 kernel/events/core.c:8707
 perf_sw_event include/linux/perf_event.h:1150 [inline]
 do_user_addr_fault arch/x86/mm/fault.c:1505 [inline]
 do_page_fault+0xaaa/0x12da 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:ffffc90002407a58 EFLAGS: 00010206
RAX: 0000000000000001 RBX: 0000000000008000 RCX: 0000000000003fcb
RDX: 0000000000008000 RSI: 0000000020f79000 RDI: ffff888057f5c035
RBP: 0000000020f74fcb R08: ffffed100afec000 R09: 0000000000000000
R10: ffffed100afebfff R11: ffff888057f5ffff R12: ffff888057f58000
R13: 0000000020f7cfcb R14: 00007ffffffff000 R15: 0000000000000000
 copy_user_generic arch/x86/include/asm/uaccess_64.h:37 [inline]
 raw_copy_from_user arch/x86/include/asm/uaccess_64.h:71 [inline]
 copyin+0x11c/0x140 lib/iov_iter.c:152
 _copy_from_iter_full+0x20a/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+0x131a/0x3210 net/ipv4/tcp.c:1335
 tcp_sendmsg+0x2b/0x40 net/ipv4/tcp.c:1433
 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:807
 sock_sendmsg_nosec net/socket.c:652 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:672
 __sys_sendto+0x21a/0x330 net/socket.c:1998
 __do_sys_sendto net/socket.c:2010 [inline]
 __se_sys_sendto net/socket.c:2006 [inline]
 __x64_sys_sendto+0xdd/0x1b0 net/socket.c:2006
 do_syscall_64+0xf6/0x790 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c849
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:00007f13f73f8c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00007f13f73f96d4 RCX: 000000000045c849
RDX: ffffffffffffffef RSI: 0000000020d7cfcb RDI: 0000000000000006
RBP: 000000000076bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000a02 R14: 00000000004ccb8a R15: 000000000076bf0c