rcu: INFO: rcu_preempt self-detected stall on CPU
rcu: 	0-....: (1 GPs behind) idle=17a/1/0x4000000000000000 softirq=30324/30325 fqs=5186 
	(t=10500 jiffies g=47021 q=2154)
NMI backtrace for cpu 0
CPU: 0 PID: 14296 Comm: syz-executor.3 Not tainted 5.9.0-rc7-next-20201001-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+0x198/0x1fb lib/dump_stack.c:118
 nmi_cpu_backtrace.cold+0x44/0xd7 lib/nmi_backtrace.c:105
 nmi_trigger_cpumask_backtrace+0x1b3/0x230 lib/nmi_backtrace.c:62
 trigger_single_cpu_backtrace include/linux/nmi.h:165 [inline]
 rcu_dump_cpu_stacks+0x1e3/0x21e kernel/rcu/tree_stall.h:337
 print_cpu_stall kernel/rcu/tree_stall.h:569 [inline]
 check_cpu_stall kernel/rcu/tree_stall.h:643 [inline]
 rcu_pending kernel/rcu/tree.c:3700 [inline]
 rcu_sched_clock_irq.cold+0x472/0xec3 kernel/rcu/tree.c:2572
 update_process_times+0x25/0xa0 kernel/time/timer.c:1712
 tick_sched_handle+0x9b/0x180 kernel/time/tick-sched.c:176
 tick_sched_timer+0x1d1/0x2a0 kernel/time/tick-sched.c:1328
 __run_hrtimer kernel/time/hrtimer.c:1524 [inline]
 __hrtimer_run_queues+0x1ce/0xea0 kernel/time/hrtimer.c:1588
 hrtimer_interrupt+0x334/0x940 kernel/time/hrtimer.c:1650
 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1080 [inline]
 __sysvec_apic_timer_interrupt+0x146/0x540 arch/x86/kernel/apic/apic.c:1097
 asm_call_irq_on_stack+0xf/0x20
 </IRQ>
 __run_sysvec_on_irqstack arch/x86/include/asm/irq_stack.h:37 [inline]
 run_sysvec_on_irqstack_cond arch/x86/include/asm/irq_stack.h:89 [inline]
 sysvec_apic_timer_interrupt+0xb2/0xf0 arch/x86/kernel/apic/apic.c:1091
 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:631
RIP: 0010:memcpy_erms+0x8/0x10 arch/x86/lib/memcpy_64.S:59
Code: cc cc eb 1e 0f 1f 00 48 89 f8 48 89 d1 48 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 c3 66 0f 1f 44 00 00 48 89 f8 48 89 d1 f3 a4 <c3> 0f 1f 80 00 00 00 00 48 89 f8 48 83 fa 20 72 7e 40 38 fe 7c 35
RSP: 0018:ffffc900077e6fd0 EFLAGS: 00000202
RAX: ffff8880a16697d8 RBX: ffffc900077e7320 RCX: 0000000000000000
RDX: 0000000000000010 RSI: ffffc900077e7120 RDI: ffff8880a16697e8
RBP: 0000000000000000 R08: 0000000000000001 R09: ffff8880a16697e7
R10: ffffed10142cd2fc R11: 0000000000000001 R12: ffffc900077e7110
R13: dffffc0000000000 R14: 1ffff92000efce69 R15: 0000000000000010
 memcpy include/linux/string.h:406 [inline]
 memcpy_common kernel/events/internal.h:174 [inline]
 __output_copy kernel/events/internal.h:178 [inline]
 perf_output_read_group kernel/events/core.c:6742 [inline]
 perf_output_read+0xd7a/0x1310 kernel/events/core.c:6775
 perf_output_sample+0x102c/0x1b60 kernel/events/core.c:6822
 __perf_event_output kernel/events/core.c:7203 [inline]
 perf_event_output_forward+0x12f/0x270 kernel/events/core.c:7217
 __perf_event_overflow+0x13c/0x370 kernel/events/core.c:8872
 perf_swevent_overflow kernel/events/core.c:8948 [inline]
 perf_swevent_event+0x347/0x550 kernel/events/core.c:8976
 do_perf_sw_event kernel/events/core.c:9089 [inline]
 ___perf_sw_event+0x31a/0x570 kernel/events/core.c:9120
 __perf_sw_event+0x54/0x130 kernel/events/core.c:9132
 perf_sw_event include/linux/perf_event.h:1171 [inline]
 mm_account_fault mm/memory.c:4600 [inline]
 handle_mm_fault+0x1219/0x4530 mm/memory.c:4651
 do_user_addr_fault+0x598/0xbf0 arch/x86/mm/fault.c:1372
 handle_page_fault arch/x86/mm/fault.c:1429 [inline]
 exc_page_fault+0xa8/0x190 arch/x86/mm/fault.c:1482
 asm_exc_page_fault+0x1e/0x30 arch/x86/include/asm/idtentry.h:583
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:ffffc900077e79d0 EFLAGS: 00010206
RAX: 0000000000000001 RBX: 0000000000008000 RCX: 0000000000004fcb
RDX: 0000000000008000 RSI: 0000000020fe8000 RDI: ffff888059013035
RBP: ffff888059010000 R08: 0000000000000001 R09: ffff888059017fff
R10: ffffed100b202fff R11: 0000000000000000 R12: 0000000020fe4fcb
R13: 0000000020fecfcb R14: 0000000000000000 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:68 [inline]
 copyin.part.0+0xe4/0x110 lib/iov_iter.c:159
 copyin lib/iov_iter.c:797 [inline]
 _copy_from_iter_full+0x22f/0x920 lib/iov_iter.c:797
 copy_from_iter_full include/linux/uio.h:155 [inline]
 skb_do_copy_data_nocache+0x145/0x2c0 include/net/sock.h:2034
 skb_copy_to_page_nocache include/net/sock.h:2060 [inline]
 tcp_sendmsg_locked+0x12ea/0x2d30 net/ipv4/tcp.c:1344
 tcp_sendmsg+0x2b/0x40 net/ipv4/tcp.c:1441
 inet_sendmsg+0x99/0xe0 net/ipv4/af_inet.c:817
 sock_sendmsg_nosec net/socket.c:651 [inline]
 sock_sendmsg+0xcf/0x120 net/socket.c:671
 __sys_sendto+0x21c/0x320 net/socket.c:1992
 __do_sys_sendto net/socket.c:2004 [inline]
 __se_sys_sendto net/socket.c:2000 [inline]
 __x64_sys_sendto+0xdd/0x1b0 net/socket.c:2000
 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45dd99
Code: 0d b4 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 db b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fec24789c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000000000002e880 RCX: 000000000045dd99
RDX: ffffffffffffffef RSI: 0000000020d7cfcb RDI: 0000000000000004
RBP: 000000000118bf78 R08: 0000000000000000 R09: 0000000000000053
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c
R13: 00007ffc10e4860f R14: 00007fec2478a9c0 R15: 000000000118bf2c