We have done over 30.000 migrations (of different VMs) between non- Skylake CPUs from qemu 2.6 to 2.11 and have never encountered the "100% freeze bug". That's why I'm sure it's related to Skylake (Intel(R) Xeon(R) Gold 6126) CPU.
I'm testing migrations with my own VM between Skylake and non-Skylake servers, but so far I'm not able to reproduce this issue... Only customer VMs experience this issue, it looks completely random... -- You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1775555 Title: guest migration 100% cpu freeze bug Status in QEMU: New Bug description: # Investigate migration cpu hog(100%) bug I have some issues when migrating from qemu 2.6.2 to qemu 2.11.1. The hypervisors are running kernel 4.9.92 on debian stretch with libvirt v4.0.0. Linux, libvirt and qemu are all custom compiled. I migrated around 21.000 vms from qemu 2.6.2 to qemu 2.11.1 and every once in a while a vm is stuck at 100% cpu after the migration from 2.6.2 to 2.11.1. This happend with about 50-60 vms so far. I attached gdb to a vcpu thread of one stuck vm, and a bt showed the following info: #0 0x00007f4f19949dd7 in ioctl () at ../sysdeps/unix/syscall-template.S:84 #1 0x0000557c9edede47 in kvm_vcpu_ioctl (cpu=cpu@entry=0x557ca1058840, type=type@entry=0xae80) at /home/dbosschieter/src/qemu-pkg/src/accel/kvm/kvm-all.c:2050 #2 0x0000557c9ededfb6 in kvm_cpu_exec (cpu=cpu@entry=0x557ca1058840) at /home/dbosschieter/src/qemu-pkg/src/accel/kvm/kvm-all.c:1887 #3 0x0000557c9edcab44 in qemu_kvm_cpu_thread_fn (arg=0x557ca1058840) at /home/dbosschieter/src/qemu-pkg/src/cpus.c:1128 #4 0x00007f4f19c0f494 in start_thread (arg=0x7f4f053f3700) at pthread_create.c:333 #5 0x00007f4f19951acf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:97 The ioctl call is a ioctl(18, KVM_RUN and it looks like it is looping inside the vm itself. I saved the state of the VM (with `virsh save`) after I found it was hanging on its vcpu threads. Then I restored this vm on a test environment running the same kernel, QEMU and libvirt version). After the restore the VM still was haning at 100% cpu usage on all the vcpus. I tried to use the perf kvm guest option to trace the guest vm with a copy of the kernel, modules and kallsyms files from inside the guest vm and I got the following trace: $ perf kvm --guest --guestkallsyms=kallsyms --guestmodules=modules record -g -p 14471 -o perf.data $ perf kvm --guest --guestkallsyms=kallsyms --guestmodules=modules report -i perf.data --stdio > analyze # To display the perf.data header info, please use --header/--header-only options. # # # Total Lost Samples: 0 # # Samples: 105K of event 'cycles' # Event count (approx.): 67588147605 # # Children Self Command Shared Object Symbol Parent symbol # ........ ........ ....... ....................... .......................................... ............. # 28.79% 28.79% :16028 [guest.kernel.kallsyms] [g] fuse_get_root_inode [other] 23.48% 23.48% :16030 [guest.kernel.kallsyms] [g] ftrace_raw_output_hrtimer_init [other] 7.32% 7.32% :16029 [guest.kernel.kallsyms] [g] do_sysfs_unregistration [other] 4.82% 4.82% :16029 [guest.kernel.kallsyms] [g] posix_cpu_clock_get [other] 4.20% 4.20% :16030 [guest.kernel.kallsyms] [g] ftrace_raw_output_timer_expire_entry [other] 3.87% 3.87% :16029 [guest.kernel.kallsyms] [g] kvm_init_debugfs [other] 3.66% 3.66% :16029 [guest.kernel.kallsyms] [g] fat_msg [other] 3.11% 3.11% :16029 [guest.kernel.kallsyms] [g] match_token [other] 3.07% 3.07% :16029 [guest.kernel.kallsyms] [g] load_balance [other] 1.87% 1.87% :16029 [guest.kernel.kallsyms] [g] kvm_pv_guest_cpu_reboot [other] 1.69% 1.69% :16031 [guest.kernel.kallsyms] [g] kvm_init_debugfs [other] 1.59% 1.59% :16029 [guest.kernel.kallsyms] [g] sys_kcmp [other] 1.19% 1.19% :16031 [guest.kernel.kallsyms] [g] save_paranoid [other] 0.82% 0.82% :16031 [guest.kernel.kallsyms] [g] kvm_pv_guest_cpu_reboot [other] 0.69% 0.69% :16031 [guest.kernel.kallsyms] [g] kvm_cpu_notify [other] 0.54% 0.54% :16031 [guest.kernel.kallsyms] [g] rcu_process_callbacks [other] 0.46% 0.46% :16030 [guest.kernel.kallsyms] [g] ftrace_raw_output_hrtimer_start [other] 0.43% 0.43% :16031 [guest.kernel.kallsyms] [g] tg_set_cfs_bandwidth [other] 0.42% 0.42% :16030 [guest.kernel.kallsyms] [g] ftrace_raw_output_hrtimer_expire_entry [other] 0.37% 0.37% :16029 [guest.kernel.kallsyms] [g] amd_get_mmconfig_range [other] 0.35% 0.35% :16031 [guest.kernel.kallsyms] [g] sys_kcmp [other] 0.35% 0.35% :16031 [guest.kernel.kallsyms] [g] console_unlock [other] 0.34% 0.34% :16029 [guest.kernel.kallsyms] [g] __fat_fs_error [other] 0.31% 0.31% :16031 [guest.kernel.kallsyms] [g] do_sysfs_unregistration [other] 0.24% 0.24% :16031 [guest.kernel.kallsyms] [g] paravirt_write_msr [other] 0.24% 0.24% :16029 [guest.kernel.kallsyms] [g] parse_no_kvmclock [other] 0.24% 0.24% :16029 [guest.kernel.kallsyms] [g] kvm_save_sched_clock_state [other] 0.21% 0.21% :16030 [guest.kernel.kallsyms] [g] ptrace_request [other] 0.20% 0.20% :16031 [guest.kernel.kallsyms] [g] print_stack_trace [other] 0.20% 0.20% :16031 [guest.kernel.kallsyms] [g] build_sched_domains [other] 0.20% 0.20% :16031 [guest.kernel.kallsyms] [g] __synchronize_srcu [other] 0.17% 0.17% :16031 [guest.kernel.kallsyms] [g] do_cpu_nanosleep [other] 0.16% 0.16% :16031 [guest.kernel.kallsyms] [g] amd_get_mmconfig_range [other] 0.16% 0.16% :16031 [guest.kernel.kallsyms] [g] irq_node_proc_show [other] 0.15% 0.15% :16031 [guest.kernel.kallsyms] [g] __srcu_read_lock [other] 0.15% 0.15% :16031 [guest.kernel.kallsyms] [g] posix_cpu_nsleep_restart [other] 0.11% 0.11% :16031 [guest.kernel.kallsyms] [g] parse_no_kvmclock [other] 0.11% 0.11% :16031 [guest.kernel.kallsyms] [g] __irq_domain_add [other] 0.11% 0.11% :16031 [guest.kernel.kallsyms] [g] print_tickdevice.isra.4 [other] 0.10% 0.10% :16031 [guest.kernel.kallsyms] [g] kvm_save_sched_clock_state [other] 0.09% 0.09% :16031 [guest.kernel.kallsyms] [g] sysfs_unbind_tick_dev [other] 0.09% 0.09% :16029 [guest.kernel.kallsyms] [g] __sched_setscheduler [other] 0.09% 0.09% :16031 [guest.kernel.kallsyms] [g] process_srcu [other] 0.08% 0.08% :16031 [guest.kernel.kallsyms] [g] avc_compute_av [other] 0.08% 0.08% :16031 [guest.kernel.kallsyms] [g] arch_remove_reservations [other] 0.08% 0.08% :16031 [guest.kernel.kallsyms] [g] __switch_to_xtra [other] 0.08% 0.08% :16031 [guest.kernel.kallsyms] [g] __create_irqs [other] 0.08% 0.08% :16031 [guest.kernel.kallsyms] [g] ftrace_raw_output_irq_handler_exit [other] 0.07% 0.07% :16031 [guest.kernel.kallsyms] [g] posix_clock_read [other] 0.07% 0.07% :16031 [guest.kernel.kallsyms] [g] posix_clock_poll [other] 0.07% 0.07% :16031 [guest.kernel.kallsyms] [g] native_cpu_up [other] 0.06% 0.06% :16031 [guest.kernel.kallsyms] [g] do_nmi [other] 0.06% 0.06% :16031 [guest.kernel.kallsyms] [g] rcu_try_advance_all_cbs [other] 0.06% 0.06% :16031 [guest.kernel.kallsyms] [g] fat_msg [other] 0.05% 0.05% :16031 [guest.kernel.kallsyms] [g] check_tsc_warp [other] 0.04% 0.04% :16031 [guest.kernel.kallsyms] [g] tick_handle_oneshot_broadcast [other] 0.03% 0.03% :16031 [guest.kernel.kallsyms] [g] set_cpu_itimer [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] arp_ignore [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] store_powersave_bias_gov_sys [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] cleanup_srcu_struct [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] create_prof_cpu_mask [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] alarm_timer_nsleep [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] time_cpufreq_notifier [other] 0.02% 0.02% :16030 [guest.kernel.kallsyms] [g] ftrace_raw_output_itimer_state [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] tick_check_new_device [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] init_timer_key [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] tick_setup_device [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] clockevents_register_device [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] __srcu_read_unlock [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] hpet_rtc_interrupt [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] init_srcu_struct [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] irq_spurious_proc_show [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] rcu_jiffies_till_stall_check [other] 0.02% 0.02% :16031 [guest.kernel.kallsyms] [g] ksoftirqd_should_run [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] ftrace_raw_output_irq_handler_entry [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] avc_denied.isra.0 [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] __fat_fs_error [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] wakeme_after_rcu [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] prof_cpu_mask_proc_write [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] srcu_barrier [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] tick_get_device [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] irq_domain_add_simple [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] synchronize_srcu_expedited [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] sysfs_show_current_tick_dev [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] tick_is_oneshot_available [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] tick_check_replacement [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] clockevents_notify [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] show_stack [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] debug_kfree [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] tick_do_broadcast.constprop.6 [other] 0.01% 0.01% :16031 [guest.kernel.kallsyms] [g] sock_rps_save_rxhash.isra.28.part.29 [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] store_ignore_nice_load.isra.3 [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] perf_trace_itimer_expire [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] hrtick_start [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] parse_probe_arg [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] wakeup_softirqd [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] tick_install_replacement [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] detach_if_pending [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] default_affinity_show [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] tick_do_periodic_broadcast [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] ftrace_raw_output_softirq [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] tasklet_kill [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] update_rq_clock [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] tasklet_init [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] arch_local_irq_enable [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] irq_affinity_proc_show [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] store_sampling_down_factor.isra.4 [other] 0.00% 0.00% :16031 [guest.kernel.kallsyms] [g] amd_get_subcaches [other] Also tried a `virsh restore` with the `--bypass-cache` option and ran a perf trace. Noticable is the different trace. See output below: # perf trace without filesystem cache: # To display the perf.data header info, please use --header/--header-only options. # # # Total Lost Samples: 0 # # Samples: 1M of event 'cycles' # Event count (approx.): 798928823821 # # Children Self Command Shared Object Symbol # ........ ........ ....... ....................... .......................................... # 25.32% 25.32% :34335 [guest.kernel.kallsyms] [g] ftrace_raw_output_hrtimer_init 9.55% 9.55% :34334 [guest.kernel.kallsyms] [g] do_sysfs_unregistration 5.83% 5.83% :34335 [guest.kernel.kallsyms] [g] ftrace_raw_output_timer_expire_entry 5.60% 5.60% :34334 [guest.kernel.kallsyms] [g] posix_cpu_clock_get 4.37% 4.37% :34334 [guest.kernel.kallsyms] [g] kvm_init_debugfs 4.30% 4.30% :34334 [guest.kernel.kallsyms] [g] fat_msg 3.63% 3.63% :34334 [guest.kernel.kallsyms] [g] match_token 3.44% 3.44% :34334 [guest.kernel.kallsyms] [g] load_balance 3.28% 3.28% :34333 [guest.kernel.kallsyms] [g] save_paranoid 2.25% 2.25% :34334 [guest.kernel.kallsyms] [g] kvm_pv_guest_cpu_reboot 2.19% 2.19% :34335 [guest.kernel.kallsyms] [g] ftrace_raw_output_hrtimer_expire_entry 1.89% 1.89% :34334 [guest.kernel.kallsyms] [g] sys_kcmp 1.73% 1.73% :34336 [guest.kernel.kallsyms] [g] kvm_init_debugfs 1.58% 1.58% :34335 [guest.kernel.kallsyms] [g] ftrace_raw_output_hrtimer_start 1.26% 1.26% :34336 [guest.kernel.kallsyms] [g] save_paranoid 1.09% 1.09% :34333 [guest.kernel.kallsyms] [g] kvm_init_debugfs 1.01% 1.01% :34333 [unknown] [u] 0x0000000000434c1b 0.94% 0.94% :34336 [guest.kernel.kallsyms] [g] tg_set_cfs_bandwidth 0.88% 0.88% :34333 [guest.kernel.kallsyms] [g] avc_denied.isra.0 0.87% 0.87% :34336 [guest.kernel.kallsyms] [g] kvm_pv_guest_cpu_reboot 0.73% 0.73% :34333 [guest.kernel.kallsyms] [g] kvm_pv_guest_cpu_reboot 0.68% 0.68% :34336 [guest.kernel.kallsyms] [g] kvm_cpu_notify 0.65% 0.65% :34336 [guest.kernel.kallsyms] [g] rcu_process_callbacks 0.57% 0.57% :34333 [guest.kernel.kallsyms] [g] paravirt_write_msr 0.56% 0.56% :34333 [guest.kernel.kallsyms] [g] avc_compute_av 0.40% 0.40% :34334 [guest.kernel.kallsyms] [g] __fat_fs_error 0.39% 0.39% :34334 [guest.kernel.kallsyms] [g] amd_get_mmconfig_range 0.39% 0.39% :34335 [guest.kernel.kallsyms] [g] ptrace_request 0.38% 0.38% :34336 [guest.kernel.kallsyms] [g] sys_kcmp 0.34% 0.34% :34333 [guest.kernel.kallsyms] [g] posix_cpu_nsleep_restart 0.32% 0.32% :34336 [guest.kernel.kallsyms] [g] do_sysfs_unregistration 0.31% 0.31% :34336 [guest.kernel.kallsyms] [g] console_unlock 0.30% 0.30% :34334 [guest.kernel.kallsyms] [g] kvm_save_sched_clock_state 0.29% 0.29% :34334 [guest.kernel.kallsyms] [g] parse_no_kvmclock 0.27% 0.27% :34333 [guest.kernel.kallsyms] [g] do_sysfs_unregistration 0.27% 0.27% :34333 [guest.kernel.kallsyms] [g] check_tsc_warp 0.26% 0.26% :34333 [guest.kernel.kallsyms] [g] ksoftirqd_should_run 0.26% 0.26% :34336 [guest.kernel.kallsyms] [g] paravirt_write_msr 0.26% 0.26% :34333 [guest.kernel.kallsyms] [g] amd_get_mmconfig_range 0.25% 0.25% :34333 [guest.kernel.kallsyms] [g] sys_kcmp 0.22% 0.22% :34336 [guest.kernel.kallsyms] [g] build_sched_domains 0.22% 0.22% :34333 [guest.kernel.kallsyms] [g] do_cpu_nanosleep 0.22% 0.22% :34333 [guest.kernel.kallsyms] [g] print_stack_trace 0.21% 0.21% :34336 [guest.kernel.kallsyms] [g] irq_node_proc_show 0.19% 0.19% :34336 [guest.kernel.kallsyms] [g] print_stack_trace 0.19% 0.19% :34336 [guest.kernel.kallsyms] [g] __srcu_read_lock 0.18% 0.18% :34336 [guest.kernel.kallsyms] [g] __synchronize_srcu 0.17% 0.17% :34333 [guest.kernel.kallsyms] [g] __create_irqs 0.17% 0.17% :34336 [guest.kernel.kallsyms] [g] do_cpu_nanosleep 0.17% 0.17% :34336 [guest.kernel.kallsyms] [g] amd_get_mmconfig_range 0.15% 0.15% :34336 [guest.kernel.kallsyms] [g] posix_cpu_nsleep_restart 0.14% 0.14% :34333 [guest.kernel.kallsyms] [g] rcu_process_callbacks 0.14% 0.14% :34333 [guest.kernel.kallsyms] [g] rcu_try_advance_all_cbs 0.13% 0.13% :34336 [guest.kernel.kallsyms] [g] parse_no_kvmclock 0.11% 0.11% :34333 [guest.kernel.kallsyms] [g] tasklet_init 0.11% 0.11% :34336 [guest.kernel.kallsyms] [g] process_srcu 0.11% 0.11% :34336 [guest.kernel.kallsyms] [g] kvm_save_sched_clock_state 0.11% 0.11% :34333 [guest.kernel.kallsyms] [g] sysfs_unbind_tick_dev 0.10% 0.10% :34336 [guest.kernel.kallsyms] [g] __switch_to_xtra 0.10% 0.10% :34334 [guest.kernel.kallsyms] [g] __sched_setscheduler 0.10% 0.10% :34333 [guest.kernel.kallsyms] [g] print_tickdevice.isra.4 0.10% 0.10% :34336 [guest.kernel.kallsyms] [g] sysfs_unbind_tick_dev 0.10% 0.10% :34336 [guest.kernel.kallsyms] [g] print_tickdevice.isra.4 0.10% 0.10% :34336 [guest.kernel.kallsyms] [g] posix_clock_read 0.09% 0.09% :34333 [guest.kernel.kallsyms] [g] parse_no_kvmclock 0.09% 0.09% :34333 [guest.kernel.kallsyms] [g] posix_clock_poll 0.09% 0.09% :34336 [guest.kernel.kallsyms] [g] __irq_domain_add 0.09% 0.09% :34336 [guest.kernel.kallsyms] [g] avc_compute_av 0.09% 0.09% :34333 [guest.kernel.kallsyms] [g] posix_clock_read 0.09% 0.09% :34333 [guest.kernel.kallsyms] [g] hpet_rtc_interrupt 0.09% 0.09% :34336 [guest.kernel.kallsyms] [g] __create_irqs 0.08% 0.08% :34336 [guest.kernel.kallsyms] [g] posix_clock_poll 0.08% 0.08% :34336 [guest.kernel.kallsyms] [g] rcu_try_advance_all_cbs 0.07% 0.07% :34336 [guest.kernel.kallsyms] [g] ftrace_raw_output_irq_handler_exit 0.07% 0.07% :34336 [guest.kernel.kallsyms] [g] arch_remove_reservations 0.07% 0.07% :34333 [guest.kernel.kallsyms] [g] native_cpu_up 0.07% 0.07% :34336 [guest.kernel.kallsyms] [g] native_cpu_up 0.07% 0.07% :34336 [guest.kernel.kallsyms] [g] check_tsc_warp 0.07% 0.07% :34333 [guest.kernel.kallsyms] [g] kvm_save_sched_clock_state 0.07% 0.07% :34333 [guest.kernel.kallsyms] [g] do_nmi 0.06% 0.06% :34336 [guest.kernel.kallsyms] [g] do_nmi 0.06% 0.06% :34335 [guest.kernel.kallsyms] [g] ftrace_raw_output_itimer_state 0.05% 0.05% :34336 [guest.kernel.kallsyms] [g] fat_msg 0.04% 0.04% :34336 [guest.kernel.kallsyms] [g] store_powersave_bias_gov_sys 0.04% 0.04% :34336 [guest.kernel.kallsyms] [g] tick_handle_oneshot_broadcast 0.04% 0.04% :34336 [guest.kernel.kallsyms] [g] set_cpu_itimer 0.04% 0.04% :34336 [guest.kernel.kallsyms] [g] cleanup_srcu_struct 0.03% 0.03% :34336 [guest.kernel.kallsyms] [g] __srcu_read_unlock 0.03% 0.03% :34336 [guest.kernel.kallsyms] [g] time_cpufreq_notifier 0.02% 0.02% :34336 [guest.kernel.kallsyms] [g] irq_spurious_proc_show 0.02% 0.02% :34336 [guest.kernel.kallsyms] [g] alarm_timer_nsleep 0.02% 0.02% :34336 [guest.kernel.kallsyms] [g] ksoftirqd_should_run 0.02% 0.02% :34333 [guest.kernel.kallsyms] [g] tg_set_cfs_bandwidth 0.02% 0.02% :34333 [guest.kernel.kallsyms] [g] create_prof_cpu_mask 0.02% 0.02% :34336 [guest.kernel.kallsyms] [g] create_prof_cpu_mask 0.02% 0.02% :34333 [guest.kernel.kallsyms] [g] fat_msg 0.02% 0.02% :34336 [guest.kernel.kallsyms] [g] tick_check_new_device 0.02% 0.02% :34333 [guest.kernel.kallsyms] [g] __switch_to_xtra 0.02% 0.02% :34336 [guest.kernel.kallsyms] [g] tick_setup_device 0.02% 0.02% :34336 [guest.kernel.kallsyms] [g] init_timer_key 0.02% 0.02% :34336 [guest.kernel.kallsyms] [g] rcu_jiffies_till_stall_check 0.02% 0.02% :34333 [guest.kernel.kallsyms] [g] ftrace_raw_output_irq_handler_exit 0.02% 0.02% :34336 [guest.kernel.kallsyms] [g] arp_ignore 0.02% 0.02% :34336 [guest.kernel.kallsyms] [g] clockevents_register_device 0.02% 0.02% :34336 [guest.kernel.kallsyms] [g] hpet_rtc_interrupt 0.02% 0.02% :34336 [guest.kernel.kallsyms] [g] init_srcu_struct 0.01% 0.01% :34333 [guest.kernel.kallsyms] [g] irq_node_proc_show 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] __fat_fs_error 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] tick_check_replacement 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] avc_denied.isra.0 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] tick_get_device 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] irq_affinity_proc_show 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] sysfs_show_current_tick_dev 0.01% 0.01% :34333 [guest.kernel.kallsyms] [g] __fat_fs_error 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] ftrace_raw_output_irq_handler_entry 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] tick_is_oneshot_available 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] irq_domain_add_simple 0.01% 0.01% :34333 [guest.kernel.kallsyms] [g] irq_spurious_proc_show 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] tick_do_broadcast.constprop.6 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] sock_rps_save_rxhash.isra.28.part.29 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] prof_cpu_mask_proc_write 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] perf_trace_itimer_expire 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] srcu_barrier 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] store_ignore_nice_load.isra.3 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] wakeme_after_rcu 0.01% 0.01% :34333 [guest.kernel.kallsyms] [g] ftrace_raw_output_irq_handler_entry 0.01% 0.01% :34333 [guest.kernel.kallsyms] [g] ftrace_raw_output_softirq 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] debug_kfree 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] clockevents_notify 0.01% 0.01% :34336 [guest.kernel.kallsyms] [g] parse_probe_arg 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] hrtick_start 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] detach_if_pending 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] tasklet_init 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] show_stack 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] wakeup_softirqd 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] arch_local_irq_enable 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] tasklet_kill 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] default_affinity_show 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] ftrace_raw_output_softirq 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] store_sampling_down_factor.isra.4 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] synchronize_srcu_expedited 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] update_rq_clock 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] tick_do_periodic_broadcast 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] tick_install_replacement 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] amd_get_subcaches 0.00% 0.00% :34334 [guest.kernel.kallsyms] [g] amd_get_subcaches 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] tick_handle_periodic 0.00% 0.00% :34336 [guest.kernel.kallsyms] [g] __page_cache_alloc I am not sure how correct the symbol mapping of perf is, so I don't know if this is usable at all. I have dumped info registers with the `qemu-monitor-command` command after the migration problematic VM and this gave the following output: RAX=0000000000001975 RBX=ffff8802342fc000 RCX=000000000000beac RDX=000000000000beaa RSI=000000000000beac RDI=ffff8802342fc000 RBP=ffff880233d3fb18 RSP=ffff880233d3fb18 R8 =0000000000000286 R9 =ffff8800a71eee40 R10=ffff8800a71eeed4 R11=000000000000000a R12=ffff8802342fc000 R13=ffffffff81cdf010 R14=ffff880233d3fb58 R15=ffff88003672b200 RIP=ffffffff817360b7 RFL=00000002 [-------] CPL=0 II=0 A20=1 SMM=0 HLT=0 ES =0000 0000000000000000 000fffff 00000000 CS =0010 0000000000000000 ffffffff 00a09b00 DPL=0 CS64 [-RA] SS =0018 0000000000000000 ffffffff 00c09300 DPL=0 DS [-WA] DS =0000 0000000000000000 000fffff 00000000 FS =0000 0000000000000000 000fffff 00000000 GS =0000 ffff88023fc00000 000fffff 00000000 LDT=0000 0000000000000000 000fffff 00000000 TR =0040 ffff88023fc04440 00002087 00008b00 DPL=0 TSS64-busy GDT= ffff88023fc0c000 0000007f IDT= ffffffffff576000 00000fff CR0=8005003b CR2=0000000000408950 CR3=0000000232098000 CR4=00000670 DR0=0000000000000000 DR1=0000000000000000 DR2=0000000000000000 DR3=0000000000000000 DR6=00000000ffff0ff0 DR7=0000000000000400 EFER=0000000000000d01 FCW=037f FSW=0000 [ST=0] FTW=00 MXCSR=00001fa0 FPR0=0000000000000000 0000 FPR1=0000000000000000 0000 FPR2=0000000000000000 0000 FPR3=0000000000000000 0000 FPR4=0000000000000000 0000 FPR5=0000000000000000 0000 FPR6=0000000000000000 0000 FPR7=0000000000000000 0000 XMM00=ffffffffff0000ff0000000000000000 XMM01=0000010101000000ffffffffffffffff XMM02=00007fe302de17006776615f64616f6c XMM03=00000000000000000000000000000000 XMM04=00000000000000000000000000000000 XMM05=00000000000000000000000000ff0000 XMM06=5b5b5b5b5b5b5b5b5b5b5b5b5b5b5b5b XMM07=20202020202020202020202020202020 XMM08=00000000000000000000000000000000 XMM09=00000000000000000000000000000000 XMM10=00000000000000000000000000000000 XMM11=00000000000000000000000000000000 XMM12=00ff000000ff0000000000000000ff00 XMM13=00000000000000000000000000000000 XMM14=00000000000000000000000000000000 XMM15=00000000000000000000000000000000 And I looped this for a minute to check were the RIP is changing to: 136 RIP=0000000000434c1b 173 RIP=ffffffff8105144a 2 RIP=ffffffff810521ff 1 RIP=ffffffff81070816 I tried to reproduce this with some manual actions prior to migrating between qemu 2.6.2 and 2.11.1 on our testing environment using similar hardware (56 core model name: Intel(R) Xeon(R) Gold 6126 CPU @ 2.60GHz) And I was not able to reproduce this, i tried the following: - restore without filesystem caches (see new perf traces below) - create vm with same kernel as stuck vm - restore paused detach net device and virtio block device (detach doesn't work) - try to do a lot of network and disk io while migrating - ecrypt fs actions during migration - migrate 4000 times between 2.6.2 -> 2.11 using loop - add extra timer calls inside guest for migrate loop (done using cyclictest) - try with guest kernel 3.13.0-145-generic, same kernel vm was running with this issue - try host clock/timer calls on 2.11.1 host prior and during migration bound on first cpu core (cyclictest -a 0 -c 1 -d 200 -H -l 1 -t 2) I asked the vm owner what he is doing on his vm, and he told me that he is using 80% of his mem around 14G of the 16G, the vm is running a tomcat 7 server and a libreoffice deamon the vm has a load of 1.0 and runs Ubuntu 14.04 with kernel 3.13.0-145. The other vms were running centos 6, centos 7, debian 7, debian 8, ubuntu 13.10, ubuntu 14.04, ubuntu 12.04 the majority of these vms are running linux kernel 3.*. The thing is I am actually out of ideas for reproducing this, and I am not sure how to pinpoint this issue, I would like some help and possible some extra tips on debugging. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1775555/+subscriptions
