After migrating VMs from XS 5.6 to 7.1, the VMs crash after some days: "domain_crash_sync called from entry.S: fault at"

XenServer 7.1 build number 137272c CPU 0-27: Vendor: GenuineIntel Model: Intel Xeon CPU E5-2680 v4 @2.40 GHz Speed: 2397 MHz   VMs: VM 1: Ubuntu 12.04 LTS, Linux 3.2.0-99-generic x86_64 Xen-VM-Params:                           user-version ( RW): 1                          is-a-template ( RW): false                          is-a-snapshot ( RO): false                            snapshot-of ( RO): <not in database>                              snapshots ( RO):                          snapshot-time ( RO): 19700101T00:00:00Z                          snapshot-info ( RO):                                 parent ( RO): <not in database>                               children ( RO):                      is-control-domain ( RO): false                            power-state ( RO): running                          memory-actual ( RO): 12884901888                          memory-target ( RO): <expensive field>                        memory-overhead ( RO): 105906176                      memory- static -max ( RW): 12884901888                     memory-dynamic-max ( RW): 12884901888                     memory-dynamic-min ( RW): 12884901888                      memory- static -min ( RW): 134217728                       suspend-VDI-uuid ( RW): <not in database>                        suspend-SR-uuid ( RW): <not in database>                           VCPUs-params (MRW):                              VCPUs-max ( RW): 4                       VCPUs-at-startup ( RW): 4                 actions-after-shutdown ( RW): Destroy                   actions-after-reboot ( RW): Restart                    actions-after-crash ( RW): Restart                          console-uuids (SRO): dfdec31a-37f2-65aa-3dd1-5d1572cff18a; 812f70e5-082b-da1e-62ab-d6c9b5ead275                                    hvm ( RO): false                               platform (MRW): nx: false ; pae: true ; acpi: true ; viridian: true ; apic: true                     allowed-operations (SRO): changing_dynamic_range; migrate_send; pool_migrate; changing_VCPUs_live; suspend; hard_reboot; hard_shutdown; clean_reboot; clean_shutdown; pause; checkpoint; snapshot                     current-operations (SRO):                     blocked-operations (MRW):                    allowed-VBD-devices (SRO): <expensive field>                    allowed-VIF-devices (SRO): <expensive field>                         possible-hosts ( RO): <expensive field>                        HVM-boot-policy ( RW):                        HVM-boot-params (MRW): order: cd                  HVM-shadow-multiplier ( RW): 1.000                              PV-kernel ( RW):                             PV-ramdisk ( RW):                                PV-args ( RW): root=/dev/xvda1 ro quiet                         PV-legacy-args ( RW):                          PV-bootloader ( RW): pygrub                     PV-bootloader-args ( RW): --kernel=/boot/vmlinuz --ramdisk=/boot/initrd.img                    last-boot-CPU-flags ( RO): vendor: GenuineIntel; features: 17c9cbf5-f6f83203-2191cbf5-00000123-00000001-000c0b39-00000000-00000000-00000000                       last-boot-record ( RO): <expensive field>                            resident-on ( RO): 43936f81-b1f0-4610-85c9-3eb36e59523a                               affinity ( RW): <not in database>                           other-config (MRW): vgpu_pci: ; import_task: OpaqueRef:10a1030c-1c9e-e2a4-70db-a1083c5cb520; last_shutdown_time: 20170512T06:49:05Z; last_shutdown_action: Destroy; last_shutdown_initiator: internal; last_shutdown_reason: halted; mac_seed: 48c257c3-8373-0b0e-c411-3ca4c88f978c; install-methods: cdrom,nfs,http,ftp; install-repository: cdrom; linux_template: true ; install-arch: amd64; debian-release: lucid; install-distro: debianlike                                 dom-id ( RO): 7                        recommendations ( RO): <restrictions><restriction field= "memory- static -max" max= "34359738368" /><restriction field= "vcpus-max" max= "8" /><restriction property= "number-of-vbds" max= "7" /><restriction property= "number-of-vifs" max= "7" /></restrictions>                          xenstore-data (MRW): vm-data:             ha-always-run ( RW) [DEPRECATED]: true                    ha-restart-priority ( RW): restart                                  blobs ( RO):                             start-time ( RO): 20170526T12:15:12Z                           install-time ( RO): 19700101T00:00:00Z                           VCPUs-number ( RO): 4                      VCPUs-utilisation (MRO): <expensive field>                             os-version (MRO): name: Ubuntu 12.04 LTS; uname: 3.2.0-99- generic ; distro: ubuntu; major: 12; minor: 04                     PV-drivers-version (MRO): major: 7; minor: 1; micro: 0; build: 137048     PV-drivers-up-to-date ( RO) [DEPRECATED]: true                                 memory (MRO):                                  disks (MRO):                                   VBDs (SRO): 4b930a27-d0f9-a8ae-d0a4-8d576f48182e; 0e536fea-b4dd-5f92-7ff4-aee542a19786; 4fa0c542-2321-d534-2524-a752e075ef05                               networks (MRO): 0/ip: 10.x.x.x; 1/ip: 10.x.x.x                    PV-drivers-detected ( RO): true                                  other (MRO): platform-feature-multiprocessor-suspend: 1; has-vendor-device: 0; feature-balloon: 1                                   live ( RO): true             guest-metrics-last-updated ( RO): 20170526T12:15:23Z                    can-use-hotplug-vbd ( RO): unspecified                    can-use-hotplug-vif ( RO): unspecified               cooperative ( RO) [DEPRECATED]: <expensive field>                                   tags (SRW):                              appliance ( RW): <not in database>                            start-delay ( RW): 0                         shutdown-delay ( RW): 0                                  order ( RW): 1                                version ( RO): 1                          generation-id ( RO): 5641993342070509531:4030427761429111578              hardware-platform-version ( RO): 0                      has-vendor-device ( RW): false                        requires-reboot ( RO): false                        reference-label ( RO):   VM 2: Ubuntu 12.04 LTS, Linux 3.2.0-98-generic x86_64 Xen-VM-Params:                           user-version ( RW): 1                          is-a-template ( RW): false                          is-a-snapshot ( RO): false                            snapshot-of ( RO): <not in database>                              snapshots ( RO):                          snapshot-time ( RO): 19700101T00:00:00Z                          snapshot-info ( RO):                                 parent ( RO): <not in database>                               children ( RO):                      is-control-domain ( RO): false                            power-state ( RO): running                          memory-actual ( RO): 4294967296                          memory-target ( RO): <expensive field>                        memory-overhead ( RO): 36700160                      memory- static -max ( RW): 4294967296                     memory-dynamic-max ( RW): 4294967296                     memory-dynamic-min ( RW): 4294967296                      memory- static -min ( RW): 134217728                       suspend-VDI-uuid ( RW): <not in database>                        suspend-SR-uuid ( RW): <not in database>                           VCPUs-params (MRW):                              VCPUs-max ( RW): 2                       VCPUs-at-startup ( RW): 2                 actions-after-shutdown ( RW): Destroy                   actions-after-reboot ( RW): Restart                    actions-after-crash ( RW): Restart                          console-uuids (SRO): cdd79a50-b96a-7935-512e-2d7ec9817002; 878ac305-73a3-3d0f-5274-ba273001717f                                    hvm ( RO): false                               platform (MRW): apic: true ; nx: false ; acpi: true ; viridian: true ; pae: true                     allowed-operations (SRO): changing_dynamic_range; migrate_send; pool_migrate; changing_VCPUs_live; suspend; hard_reboot; hard_shutdown; clean_reboot; clean_shutdown; pause; checkpoint; snapshot                     current-operations (SRO):                     blocked-operations (MRW):                    allowed-VBD-devices (SRO): <expensive field>                    allowed-VIF-devices (SRO): <expensive field>                         possible-hosts ( RO): <expensive field>                        HVM-boot-policy ( RW):                        HVM-boot-params (MRW): order: cd                  HVM-shadow-multiplier ( RW): 1.000                              PV-kernel ( RW):                             PV-ramdisk ( RW):                                PV-args ( RW): root=/dev/xvda1 ro quiet                         PV-legacy-args ( RW):                          PV-bootloader ( RW): pygrub                     PV-bootloader-args ( RW): --kernel=/boot/vmlinuz --ramdisk=/boot/initrd.img                    last-boot-CPU-flags ( RO): vendor: GenuineIntel; features: 17c9cbf5-f6f83203-2191cbf5-00000123-00000001-000c0b39-00000000-00000000-00000000                       last-boot-record ( RO): <expensive field>                            resident-on ( RO): 43936f81-b1f0-4610-85c9-3eb36e59523a                               affinity ( RW): <not in database>                           other-config (MRW): vgpu_pci: ; import_task: OpaqueRef:dc81ced1-8e2b-9348-f018-37b5502e6ab0; last_shutdown_time: 20170511T14:37:59Z; last_shutdown_action: Destroy; last_shutdown_initiator: external; last_shutdown_reason: halted; mac_seed: f15471c7-bcd3-f889-5060-ada6a6b57cc9; install-methods: cdrom,nfs,http,ftp; install-repository: cdrom; linux_template: true ; install-arch: amd64; debian-release: lucid; install-distro: debianlike                                 dom-id ( RO): 8                        recommendations ( RO): <restrictions><restriction field= "memory- static -max" max= "34359738368" /><restriction field= "vcpus-max" max= "8" /><restriction property= "number-of-vbds" max= "7" /><restriction property= "number-of-vifs" max= "7" /></restrictions>                          xenstore-data (MRW): vm-data:             ha-always-run ( RW) [DEPRECATED]: true                    ha-restart-priority ( RW): restart                                  blobs ( RO):                             start-time ( RO): 20170531T18:37:29Z                           install-time ( RO): 19700101T00:00:00Z                           VCPUs-number ( RO): 2                      VCPUs-utilisation (MRO): <expensive field>                             os-version (MRO): name: Ubuntu 12.04.3 LTS; uname: 3.2.0-98- generic ; distro: ubuntu; major: 12; minor: 04                     PV-drivers-version (MRO): major: 7; minor: 1; micro: 0; build: 137048     PV-drivers-up-to-date ( RO) [DEPRECATED]: true                                 memory (MRO):                                  disks (MRO):                                   VBDs (SRO): a9a47ae2-fb9d-a6a6-fe2f-fc401cda9d7a; 9ee4cf23-8a2d-419b-d4df-256fd8afad4e; 3d1fe27a-453c-1abe-3c68-b93a18f37b3a                               networks (MRO): 0/ip: 10.7.6.223                    PV-drivers-detected ( RO): true                                  other (MRO): platform-feature-multiprocessor-suspend: 1; has-vendor-device: 0; feature-balloon: 1                                   live ( RO): true             guest-metrics-last-updated ( RO): 20170531T18:37:47Z                    can-use-hotplug-vbd ( RO): unspecified                    can-use-hotplug-vif ( RO): unspecified               cooperative ( RO) [DEPRECATED]: <expensive field>                                   tags (SRW): site:rzl, TSM_Node, RL_24, OL_1, Status:Backup                              appliance ( RW): <not in database>                            start-delay ( RW): 0                         shutdown-delay ( RW): 0                                  order ( RW): 1                                version ( RO): 1                          generation-id ( RO): 2671439301952956896:6658159543046652              hardware-platform-version ( RO): 0                      has-vendor-device ( RW): false                        requires-reboot ( RO): false                        reference-label ( RO):