Unable to migrate container

This bug is caused by the new nsroot= patch introduced in:

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1560489

To fix it, we have two options:

1. patch the kernel again to allow nsroot= to be supplied on mount (I've spoken to hallyn and he's going to write a patch to allow this soon)

2. patch CRIU (with a patch that won't go upstream in CRIU, because we're expecting the mount patch from 1 to land) to trim nsroot before restoring: https://github.com/tych0/criu/commit/5691a6b38c84d23707008d465bbb25ef3c8a57eb

In either case, we also need to apply this patch to CRIU: https://github.com/xemul/criu/commit/d071ab161a7a147673253a4f460c1f1164acd470

Status changed to 'Confirmed' because the bug affects multiple users.

This is fixed with -ubuntu3 I believe.

This bug was fixed in the package linux - 4.4.0-18.34

---------------
linux (4.4.0-18.34) xenial; urgency=low

  [ Tim Gardner ]

  * Release Tracking Bug
    - LP: #1566868

  * [i915_bpo] Fix RC6 on SKL GT3 & GT4 (LP: #1564759)
    - SAUCE: i915_bpo: drm/i915/skl: Fix rc6 based gpu/system hang
    - SAUCE: i915_bpo: drm/i915/skl: Fix spurious gpu hang with gt3/gt4 revs

  * CONFIG_ARCH_ROCKCHIP not enabled in armhf generic kernel (LP: #1566283)
    - [Config] CONFIG_ARCH_ROCKCHIP=y

  * [Feature] Memory Bandwidth Monitoring (LP: #1397880)
    - perf/x86/cqm: Fix CQM handling of grouping events into a cache_group
    - perf/x86/cqm: Fix CQM memory leak and notifier leak
    - x86/cpufeature: Carve out X86_FEATURE_*
    - Merge branch 'timers-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
    - x86/topology: Create logical package id
    - perf/x86/mbm: Add Intel Memory B/W Monitoring enumeration and init
    - perf/x86/mbm: Add memory bandwidth monitoring event management
    - perf/x86/mbm: Implement RMID recycling
    - perf/x86/mbm: Add support for MBM counter overflow handling

  * User namespace mount updates (LP: #1566505)
    - SAUCE: quota: Require that qids passed to dqget() be valid and map into s_user_ns
    - SAUCE: fs: Allow superblock owner to change ownership of inodes with unmappable ids
    - SAUCE: fuse: Don't initialize user_id or group_id in mount options
    - SAUCE: cgroup: Use a new super block when mounting in a cgroup namespace
    - SAUCE: fs: fix a posible leak of allocated superblock

  * [arm64] kernel BUG at /build/linux-StrpB2/linux-4.4.0/fs/ext4/inode.c:2394!
    (LP: #1566518)
    - arm64: Honour !PTE_WRITE in set_pte_at() for kernel mappings
    - arm64: Update PTE_RDONLY in set_pte_at() for PROT_NONE permission

  * [Feature]USB core and xHCI tasks for USB 3.1 SuperSpeedPlus (SSP) support
    for Alpine Ridge on SKL (LP: #1519623)
    - usb: define USB_SPEED_SUPER_PLUS speed for SuperSpeedPlus USB3.1 devices
    - usb: set USB 3.1 roothub device speed to USB_SPEED_SUPER_PLUS
    - usb: show speed "10000" in sysfs for USB 3.1 SuperSpeedPlus devices
    - usb: add device descriptor for usb 3.1 root hub
    - usb: Support USB 3.1 extended port status request
    - xhci: Make sure xhci handles USB_SPEED_SUPER_PLUS devices.
    - xhci: set roothub speed to USB_SPEED_SUPER_PLUS for USB3.1 capable controllers
    - xhci: USB 3.1 add default Speed Attributes to SuperSpeedPlus device capability
    - xhci: set slot context speed field to SuperSpeedPlus for USB 3.1 SSP devices
    - usb: Add USB3.1 SuperSpeedPlus Isoc Endpoint Companion descriptor
    - usb: Parse the new USB 3.1 SuperSpeedPlus Isoc endpoint companion descriptor
    - usb: Add USB 3.1 Precision time measurement capability descriptor support
    - xhci: refactor and cleanup endpoint initialization.
    - xhci: Add SuperSpeedPlus high bandwidth isoc support to xhci endpoints
    - xhci: cleanup isoc tranfers queuing code
    - xhci: Support extended burst isoc TRB structure used by xhci 1.1 for USB 3.1
    - SAUCE: (noup) usb: fix regression in SuperSpeed endpoint descriptor parsing

  * wrong/missing permissions for device f...