On Mon, Nov 12, 2012 at 08:47:11PM -0000, Steven Noonan wrote:
> Stefan,
> 
> I did our internal SSD and network performance testing qualifications on
> hi1.4xlarge with CONFIG_PARAVIRT_SPINLOCKS=n in the kernel build.
> There's very little discernible difference in performance (within
> statistical noise ranges), and the benefits of disabling it are pretty
> clear. Can CONFIG_PARAVIRT_SPINLOCKS be disabled in the Ubuntu -virtual
> kernel so we can close out this bug, please?

Yikes, that would be quite bad for overcommitted scenarios and
for running the guest on non-PLE hardware.

I am looking at the bug now to get an idea of what is happening
and how to reproduce it.
> 
> -- 
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1011792
> 
> Title:
>   Kernel lockup running 3.0.0 and 3.2.0 on multiple EC2 instance types
> 
> Status in “linux” package in Ubuntu:
>   Confirmed
> Status in “linux-lts-backport-oneiric” package in Ubuntu:
>   Confirmed
> 
> Bug description:
>   Scheduler deadlocks have been observed on c1.xlarge EC2 instances
>   running 10.04.3 LTS with the  3.0.0-20-virtual Oneiric backport
>   kernel. The symptoms appear similar to bug 929941, where multiple CPUs
>   are waiting on scheduler runqueue locks. But in this case, only a few
>   CPUs are stuck.
> 
>   A typical set of stack traces from the guest state looks like:
> 
>   VCPU0
>   rip: ffffffff810013aa hypercall_page+0x3aa
>   flags: 00001202 i nz
>   rsp: ffff8801b3c27910
>   rax: 0000000000000000   rcx: ffffffff810013aa   rdx: ffff8801b3c27954
>   rbx: ffff88000265cb30   rsi: ffff8801b3c27938   rdi: 0000000000000003
>   rbp: ffff8801b3c27958    r8: 0000000000000001    r9: 0000000000000001
>   r10: 0000000000000000   r11: 0000000000000202   r12: 0000000000000011
>   r13: 0000000000000001   r14: 0000000000000001   r15: 0000000000000000
>    cs: e033        ss: e02b        ds: 0000        es: 0000
>    fs: 0000 @ 00007f4ce223f700
>    gs: 0000 @ ffff8801bfed4000/0000000000000000
> 
>   cr0: 80050033
>   cr2: 0061ade0
>   cr3: 0e93d000
>   cr4: 00002660
> 
>   dr0: 00000000
>   dr1: 00000000
>   dr2: 00000000
>   dr3: 00000000
>   dr6: ffff0ff0
>   dr7: 00000400
>   Code (instr addr ffffffff810013aa)
>   cc cc cc cc cc cc cc cc cc cc cc 51 41 53 b8 1d 00 00 00 0f 05 <41> 5b 59 c3 cc cc cc cc cc cc cc
> 
>   
>   Stack:
>    0000000000000246 0000000000000000 ffffffff81394b42 ffff8801b3c27938
>    0000000000000000 ffff8801b3c27954 ffffffff00000001 0000000000000000
>    0000000481394ad6 ffff8801b3c27968 ffffffff81394b60 ffff8801b3c279b8
>    ffffffff8100933f ffff8801b3c27a48 0000000000000000 ffff8801b3c27998
> 
>   Call Trace:
>     [<ffffffff810013aa>] hypercall_page+0x3aa  <--
>     [<ffffffff81394b42>] xen_poll_irq_timeout+0x42
>     [<ffffffff81394b60>] xen_poll_irq+0x10
>     [<ffffffff8100933f>] xen_spin_lock_slow+0x7f
>     [<ffffffff81009435>] xen_spin_lock_flags+0x75
>     [<ffffffff8160365f>] _raw_spin_lock_irqsave+0x2f
>     [<ffffffff8104ee50>] task_rq_lock+0x40
>     [<ffffffff8104f069>] task_sched_runtime+0x29
>     [<ffffffff81085f38>] thread_group_cputime+0x88
>     [<ffffffff812c4dc9>] apparmor_ptrace_access_check+0x39
>     [<ffffffff81051593>] thread_group_times+0x33
>     [<ffffffff811d4192>] do_task_stat+0x6d2
>     [<ffffffff8160361e>] _raw_spin_lock+0xe
>     [<ffffffff8119165f>] seq_open+0x4f
>     [<ffffffff811d0380>] sched_autogroup_show+0x70
>     [<ffffffff811d0380>] sched_autogroup_show+0x70
>     [<ffffffff8119173a>] single_open+0x7a
>     [<ffffffff811cdbf0>] sched_open+0x20
>     [<ffffffff811cdc0b>] proc_single_open+0x1b
>     [<ffffffff8118e460>] mntput_no_expire+0x60
>     [<ffffffff8118e5ad>] mntput+0x1d
>     [<ffffffff811d4624>] proc_tgid_stat+0x14
>     [<ffffffff811d03e1>] proc_single_show+0x61
>     [<ffffffff81191be2>] seq_read+0xf2
>     [<ffffffff8116fe35>] vfs_read+0xc5
>     [<ffffffff81170001>] sys_read+0x51
>     [<ffffffff8160ba02>] system_call_fastpath+0x16
> 
>   
>   VCPU1
>   rip: ffffffff8105a777 try_to_wake_up+0xd7
>   flags: 00001202 i nz
>   rsp: ffff8801bfef28f0
>   rax: 0000000000000003   rcx: 0000000000000000   rdx: 0000000000000001
>   rbx: 0000000000012980   rsi: ffff8801b1990078   rdi: 0000000000000000
>   rbp: ffff8801bfef2950    r8: 0000000000000000    r9: 0000000000000000
>   r10: 0000000000000000   r11: 00000000fb981853   r12: ffff88000265c530
>   r13: 0000000000000000   r14: ffff88000265cb30   r15: 0000000000000000
>    cs: e033        ss: e02b        ds: 0000        es: 0000
>    fs: 0000 @ 00007ff68926c700
>    gs: 0000 @ ffff8801bfeef000/0000000000000000
> 
>   cr0: 8005003b
>   cr2: 00441d80
>   cr3: 1174cb000
>   cr4: 00002660
> 
>   dr0: 00000000
>   dr1: 00000000
>   dr2: 00000000
>   dr3: 00000000
>   dr6: ffff0ff0
>   dr7: 00000400
>   Code (instr addr ffffffff8105a777)
>   00 00 eb 0c 66 2e 0f 1f 84 00 00 00 00 00 f3 90 41 8b 54 24 28 <85> d2 75 f5 49 8b 14 24 31 c0 83
> 
>   
>   Stack:
>    0000000000000000 ffff8801b41d2858 ffff8801bfef2950 ffffffff8153e51e
>    0000000300000004 ffff8801b1990078 ffff8801bfef2930 ffff8800026f6c18
>    0000000000000001 ffff8800026f6c30 0000000000000000 0000000000000000
>    ffff8801bfef2960 ffffffff8105a962 ffff8801bfef29b0 ffffffff81049709
> 
>   Call Trace:
>     [<ffffffff8105a777>] try_to_wake_up+0xd7  <--
>     [<ffffffff8153e51e>] ip_finish_output+0x16e
>     [<ffffffff8105a962>] default_wake_function+0x12
>     [<ffffffff81049709>] __wake_up_common+0x59
>     [<ffffffff81049758>] __wake_up_locked+0x18
>     [<ffffffff811afcf4>] ep_poll_callback+0xa4
>     [<ffffffff81049709>] __wake_up_common+0x59
>     [<ffffffff8104ed53>] __wake_up_sync_key+0x53
>     [<ffffffff814f3d2e>] sock_def_readable+0x3e
>     [<ffffffff8155255a>] tcp_rcv_established+0x26a
>     [<ffffffff8100742d>] xen_force_evtchn_callback+0xd
>     [<ffffffff81007b72>] check_events+0x12
>     [<ffffffff8155a9a5>] tcp_v4_do_rcv+0x125
>     [<ffffffff8155c169>] tcp_v4_rcv+0x5a9
>     [<ffffffff8153854d>] ip_local_deliver_finish+0xdd
>     [<ffffffff81538790>] ip_local_deliver+0x80
>     [<ffffffff81537db9>] ip_rcv_finish+0x119
>     [<ffffffff815383a8>] ip_rcv+0x228
>     [<ffffffff815d0afd>] packet_rcv_spkt+0x4d
>     [<ffffffff815036b0>] __netif_receive_skb+0x1e0
>     [<ffffffff81506790>] netif_receive_skb+0x80
>     [<ffffffff814614f4>] handle_incoming_queue+0x134
>     [<ffffffff81461fd7>] xennet_poll+0x277
>     [<ffffffff81506ff8>] net_rx_action+0x108
>     [<ffffffff8160361e>] _raw_spin_lock+0xe
>     [<ffffffff8106889f>] __do_softirq+0xbf
>     [<ffffffff810d3f7d>] handle_edge_irq+0x9d
>     [<ffffffff8160cc1c>] call_softirq+0x1c
>     [<ffffffff8100d3d5>] do_softirq+0x65
>     [<ffffffff8106869d>] irq_exit+0xbd
>     [<ffffffff81394ee5>] xen_evtchn_do_upcall+0x35
>     [<ffffffff8160cc6e>] xen_do_hypervisor_callback+0x1e
> 
>   
>   VCPU2
>   rip: ffffffff810013aa hypercall_page+0x3aa
>   flags: 00001202 i nz
>   rsp: ffff8801bff0da00
>   rax: 0000000000000000   rcx: ffffffff810013aa   rdx: ffff8801bff0da44
>   rbx: ffff8800026f6c00   rsi: ffff8801bff0da28   rdi: 0000000000000003
>   rbp: ffff8801bff0da48    r8: 00000000000000c3    r9: 000000000000c110
>   r10: 0000000000100000   r11: 0000000000000202   r12: 000000000000001d
>   r13: 0000000000000001   r14: 0000000000000001   r15: 0000000000000000
>    cs: e033        ss: e02b        ds: 0000        es: 0000
>    fs: 0000 @ 00007f408128b700
>    gs: 0000 @ ffff8801bff0a000/0000000000000000
> 
>   cr0: 80050033
>   cr2: 0061ade0
>   cr3: 289f2000
>   cr4: 00002660
> 
>   dr0: 00000000
>   dr1: 00000000
>   dr2: 00000000
>   dr3: 00000000
>   dr6: ffff0ff0
>   dr7: 00000400
>   Code (instr addr ffffffff810013aa)
>   cc cc cc cc cc cc cc cc cc cc cc 51 41 53 b8 1d 00 00 00 0f 05 <41> 5b 59 c3 cc cc cc cc cc cc cc
> 
>   
>   Stack:
>    0000000000112000 0000000000000000 ffffffff81394b42 ffff8801bff0da28
>    0000000000000000 ffff8801bff0da44 ffffffff00000001 0000000000000000
>    0000001081394ad6 ffff8801bff0da58 ffffffff81394b60 ffff8801bff0daa8
>    ffffffff8100933f ffff8801bff0da88 0000000000000000 ffff8801b3d14530
> 
>   Call Trace:
>     [<ffffffff810013aa>] hypercall_page+0x3aa  <--
>     [<ffffffff81394b42>] xen_poll_irq_timeout+0x42
>     [<ffffffff81394b60>] xen_poll_irq+0x10
>     [<ffffffff8100933f>] xen_spin_lock_slow+0x7f
>     [<ffffffff81009435>] xen_spin_lock_flags+0x75
>     [<ffffffff8160365f>] _raw_spin_lock_irqsave+0x2f
>     [<ffffffff811afca9>] ep_poll_callback+0x59
>     [<ffffffff816036ae>] _raw_spin_unlock_irqrestore+0x1e
>     [<ffffffff81049709>] __wake_up_common+0x59
>     [<ffffffff8104ed53>] __wake_up_sync_key+0x53
>     [<ffffffff814f3d2e>] sock_def_readable+0x3e
>     [<ffffffff8154ef50>] tcp_data_queue+0x300
>     [<ffffffff81552639>] tcp_rcv_established+0x349
>     [<ffffffff8155a9a5>] tcp_v4_do_rcv+0x125
>     [<ffffffff8155c169>] tcp_v4_rcv+0x5a9
>     [<ffffffff81054e18>] enqueue_sleeper+0x188
>     [<ffffffff8153854d>] ip_local_deliver_finish+0xdd
>     [<ffffffff81538790>] ip_local_deliver+0x80
>     [<ffffffff81537db9>] ip_rcv_finish+0x119
>     [<ffffffff815383a8>] ip_rcv+0x228
>     [<ffffffff815036b0>] __netif_receive_skb+0x1e0
>     [<ffffffff81007b5f>] xen_restore_fl_direct_reloc+0x4
>     [<ffffffff810d7af4>] rcu_enter_nohz+0x44
>     [<ffffffff81503aeb>] process_backlog+0x10b
>     [<ffffffff810d10b5>] handle_irq_event_percpu+0xb5
>     [<ffffffff81506ff8>] net_rx_action+0x108
>     [<ffffffff8100742d>] xen_force_evtchn_callback+0xd
>     [<ffffffff8106889f>] __do_softirq+0xbf
>     [<ffffffff81007b5f>] xen_restore_fl_direct_reloc+0x4
>     [<ffffffff8160cc1c>] call_softirq+0x1c
> 
>   
>   VCPU3
>   rip: ffffffff810013aa hypercall_page+0x3aa
>   flags: 00001202 i nz
>   rsp: ffff8801b1993b10
>   rax: 0000000000000000   rcx: ffffffff810013aa   rdx: ffff8801b1993b54
>   rbx: ffff8801bff01980   rsi: ffff8801b1993b38   rdi: 0000000000000003
>   rbp: ffff8801b1993b58    r8: ffff8801bf004760    r9: 0000000000000040
>   r10: 000000000000001d   r11: 0000000000000202   r12: 0000000000000023
>   r13: 0000000000000001   r14: 0000000000000001   r15: 0000000000000000
>    cs: e033        ss: e02b        ds: 0000        es: 0000
>    fs: 0000 @ 00007f1a15c06700
>    gs: 0000 @ ffff8801bff25000/0000000000000000
> 
>   cr0: 80050033
>   cr2: 7f78b037de20
>   cr3: 0e9c9000
>   cr4: 00002660
> 
>   dr0: 00000000
>   dr1: 00000000
>   dr2: 00000000
>   dr3: 00000000
>   dr6: ffff0ff0
>   dr7: 00000400
>   Code (instr addr ffffffff810013aa)
>   cc cc cc cc cc cc cc cc cc cc cc 51 41 53 b8 1d 00 00 00 0f 05 <41> 5b 59 c3 cc cc cc cc cc cc cc
> 
>   
>   Stack:
>    0000000000000001 0000000000000000 ffffffff81394b42 ffff8801b1993b38
>    0000000000000000 ffff8801b1993b54 ffffffff00000001 0000000000000000
>    0000001681394ad6 ffff8801b1993b68 ffffffff81394b60 ffff8801b1993bb8
>    ffffffff8100933f 0000000000000000 0000000000000000 0000000000000000
> 
>   Call Trace:
>     [<ffffffff810013aa>] hypercall_page+0x3aa  <--
>     [<ffffffff81394b42>] xen_poll_irq_timeout+0x42
>     [<ffffffff81394b60>] xen_poll_irq+0x10
>     [<ffffffff8100933f>] xen_spin_lock_slow+0x7f
>     [<ffffffff81009496>] xen_spin_lock+0x56
>     [<ffffffff8160361e>] _raw_spin_lock+0xe
>     [<ffffffff8104d90d>] double_rq_lock+0x2d
>     [<ffffffff81059f15>] load_balance+0x1f5
>     [<ffffffff81601576>] __schedule+0x7e6
>     [<ffffffff8160165f>] schedule+0x3f
>     [<ffffffff816025b5>] schedule_hrtimeout_range_clock+0xc5
>     [<ffffffff810881c0>] update_rmtp+0x80
>     [<ffffffff81089524>] hrtimer_start_range_ns+0x14
>     [<ffffffff81602663>] schedule_hrtimeout_range+0x13
>     [<ffffffff811af9f8>] ep_poll+0x2d8
>     [<ffffffff8105a950>] try_to_wake_up+0x2b0
>     [<ffffffff81290c2b>] security_file_permission+0x8b
>     [<ffffffff8116fee0>] vfs_read+0x170
>     [<ffffffff811afb35>] sys_epoll_wait+0xc5
>     [<ffffffff8160ba02>] system_call_fastpath+0x16
> 
>   
>   VCPU4
>   rip: ffffffff810013aa hypercall_page+0x3aa
>   flags: 00001246 i z p
>   rsp: ffff8801b45f5ed8
>   rax: 0000000000000000   rcx: ffffffff810013aa   rdx: 0000000000000000
>   rbx: ffff8801b45f4010   rsi: 0000000000000000   rdi: 0000000000000001
>   rbp: ffff8801b45f5ef0    r8: 0000000000000000    r9: 0000000000000000
>   r10: 0000000000000000   r11: 0000000000000246   r12: 0000000000000004
>   r13: 0000000000000000   r14: 0000000000000000   r15: 0000000000000000
>    cs: e033        ss: e02b        ds: 002b        es: 002b
>    fs: 0000 @ 00007fe085364700
>    gs: 0000 @ ffff8801bff40000/0000000000000000
> 
>   cr0: 8005003b
>   cr2: 7f7127c10000
>   cr3: 29c76000
>   cr4: 00002660
> 
>   dr0: 00000000
>   dr1: 00000000
>   dr2: 00000000
>   dr3: 00000000
>   dr6: ffff0ff0
>   dr7: 00000400
>   Code (instr addr ffffffff810013aa)
>   cc cc cc cc cc cc cc cc cc cc cc 51 41 53 b8 1d 00 00 00 0f 05 <41> 5b 59 c3 cc cc cc cc cc cc cc
> 
>   
>   Stack:
>    0000000000000000 0000000000000000 ffffffff81007490 ffff8801b45f5f10
>    ffffffff81013c3d ffff8801b45f4010 ffffffff81cc7f48 ffff8801b45f5f40
>    ffffffff8100b0c7 ffffffff81007b19 6811f30c74562efe 0000000000000000
>    0000000000000000 ffff8801b45f5f50 ffffffff815f523d 0000000000000000
> 
>   Call Trace:
>     [<ffffffff810013aa>] hypercall_page+0x3aa  <--
>     [<ffffffff81007490>] xen_safe_halt+0x10
>     [<ffffffff81013c3d>] default_idle+0x5d
>     [<ffffffff8100b0c7>] cpu_idle+0xb7
>     [<ffffffff81007b19>] xen_irq_enable_direct_reloc+0x4
>     [<ffffffff815f523d>] cpu_bringup_and_idle+0xe
> 
>   
>   VCPU5
>   rip: ffffffff810013aa hypercall_page+0x3aa
>   flags: 00001246 i z p
>   rsp: ffff8801b45f7ed8
>   rax: 0000000000000000   rcx: ffffffff810013aa   rdx: 0000000000000000
>   rbx: ffff8801b45f6010   rsi: 0000000000000000   rdi: 0000000000000001
>   rbp: ffff8801b45f7ef0    r8: 0000000000000000    r9: 0000000000000000
>   r10: 0000000000000000   r11: 0000000000000246   r12: 0000000000000005
>   r13: 0000000000000000   r14: 0000000000000000   r15: 0000000000000000
>    cs: e033        ss: e02b        ds: 002b        es: 002b
>    fs: 0000 @ 00007fcf9cf7a700
>    gs: 0000 @ ffff8801bff5b000/0000000000000000
> 
>   cr0: 8005003b
>   cr2: 7faf54aac360
>   cr3: 325e8000
>   cr4: 00002660
> 
>   dr0: 00000000
>   dr1: 00000000
>   dr2: 00000000
>   dr3: 00000000
>   dr6: ffff0ff0
>   dr7: 00000400
>   Code (instr addr ffffffff810013aa)
>   cc cc cc cc cc cc cc cc cc cc cc 51 41 53 b8 1d 00 00 00 0f 05 <41> 5b 59 c3 cc cc cc cc cc cc cc
> 
>   
>   Stack:
>    0000000000000000 0000000000000000 ffffffff81007490 ffff8801b45f7f10
>    ffffffff81013c3d ffff8801b45f6010 ffffffff81cc7f48 ffff8801b45f7f40
>    ffffffff8100b0c7 ffffffff81007b19 afec8dc6140892fe 0000000000000000
>    0000000000000000 ffff8801b45f7f50 ffffffff815f523d 0000000000000000
> 
>   Call Trace:
>     [<ffffffff810013aa>] hypercall_page+0x3aa  <--
>     [<ffffffff81007490>] xen_safe_halt+0x10
>     [<ffffffff81013c3d>] default_idle+0x5d
>     [<ffffffff8100b0c7>] cpu_idle+0xb7
>     [<ffffffff81007b19>] xen_irq_enable_direct_reloc+0x4
>     [<ffffffff815f523d>] cpu_bringup_and_idle+0xe
> 
>   
>   VCPU6
>   rip: ffffffff810013aa hypercall_page+0x3aa
>   flags: 00001246 i z p
>   rsp: ffff8801b4601ed8
>   rax: 0000000000000000   rcx: ffffffff810013aa   rdx: 0000000000000000
>   rbx: ffff8801b4600010   rsi: 0000000000000000   rdi: 0000000000000001
>   rbp: ffff8801b4601ef0    r8: 0000000000000000    r9: 0000000000000000
>   r10: 0000000000000000   r11: 0000000000000246   r12: 0000000000000006
>   r13: 0000000000000000   r14: 0000000000000000   r15: 0000000000000000
>    cs: e033        ss: e02b        ds: 002b        es: 002b
>    fs: 0000 @ 00007ff5deb9b700
>    gs: 0000 @ ffff8801bff76000/0000000000000000
> 
>   cr0: 8005003b
>   cr2: 7faf5345dff8
>   cr3: 10160000
>   cr4: 00002660
> 
>   dr0: 00000000
>   dr1: 00000000
>   dr2: 00000000
>   dr3: 00000000
>   dr6: ffff0ff0
>   dr7: 00000400
>   Code (instr addr ffffffff810013aa)
>   cc cc cc cc cc cc cc cc cc cc cc 51 41 53 b8 1d 00 00 00 0f 05 <41> 5b 59 c3 cc cc cc cc cc cc cc
> 
>   
>   Stack:
>    0000000000000000 0000000000000000 ffffffff81007490 ffff8801b4601f10
>    ffffffff81013c3d ffff8801b4600010 ffffffff81cc7f48 ffff8801b4601f40
>    ffffffff8100b0c7 ffffffff81007b19 f6fcdef4e1be86f4 0000000000000000
>    0000000000000000 ffff8801b4601f50 ffffffff815f523d 0000000000000000
> 
>   Call Trace:
>     [<ffffffff810013aa>] hypercall_page+0x3aa  <--
>     [<ffffffff81007490>] xen_safe_halt+0x10
>     [<ffffffff81013c3d>] default_idle+0x5d
>     [<ffffffff8100b0c7>] cpu_idle+0xb7
>     [<ffffffff81007b19>] xen_irq_enable_direct_reloc+0x4
>     [<ffffffff815f523d>] cpu_bringup_and_idle+0xe
> 
>   
>   VCPU7
>   rip: ffffffff810013aa hypercall_page+0x3aa
>   flags: 00001246 i z p
>   rsp: ffff8801b4603ed8
>   rax: 0000000000000000   rcx: ffffffff810013aa   rdx: 0000000000000000
>   rbx: ffff8801b4602010   rsi: 0000000000000000   rdi: 0000000000000001
>   rbp: ffff8801b4603ef0    r8: 0000000000000000    r9: 0000000000000000
>   r10: 0000000000000000   r11: 0000000000000246   r12: 0000000000000007
>   r13: 0000000000000000   r14: 0000000000000000   r15: 0000000000000000
>    cs: e033        ss: e02b        ds: 002b        es: 002b
>    fs: 0000 @ 00007fe081751700
>    gs: 0000 @ ffff8801bff91000/0000000000000000
> 
>   cr0: 8005003b
>   cr2: 7faf54bdfde0
>   cr3: 29c76000
>   cr4: 00002660
> 
>   dr0: 00000000
>   dr1: 00000000
>   dr2: 00000000
>   dr3: 00000000
>   dr6: ffff0ff0
>   dr7: 00000400
>   Code (instr addr ffffffff810013aa)
>   cc cc cc cc cc cc cc cc cc cc cc 51 41 53 b8 1d 00 00 00 0f 05 <41> 5b 59 c3 cc cc cc cc cc cc cc
> 
>   
>   Stack:
>    0000000000000000 0000000000000000 ffffffff81007490 ffff8801b4603f10
>    ffffffff81013c3d ffff8801b4602010 ffffffff81cc7f48 ffff8801b4603f40
>    ffffffff8100b0c7 ffffffff81007b19 0c1d63da394a80a3 0000000000000000
>    0000000000000000 ffff8801b4603f50 ffffffff815f523d 0000000000000000
> 
>   Call Trace:
>     [<ffffffff810013aa>] hypercall_page+0x3aa  <--
>     [<ffffffff81007490>] xen_safe_halt+0x10
>     [<ffffffff81013c3d>] default_idle+0x5d
>     [<ffffffff8100b0c7>] cpu_idle+0xb7
>     [<ffffffff81007b19>] xen_irq_enable_direct_reloc+0x4
>     [<ffffffff815f523d>] cpu_bringup_and_idle+0xe
> 
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