Public bug reported:

== Comment: #0 - Bernd-Rainer Bresser <bress...@de.ibm.com> - 2016-12-05 
04:27:00 ==
+++ This bug was initially created as a clone of Bug #147836 +++

---Problem Description---
When the system is installed with encrypted swap partition the attempt to swap 
ends in a system freeze. No error, no dump, the system needs to be reloaded.
 
Contact Information = Bernd-Rainer Bresser/Germany/IBM, Wen Yi AG Gao/China/IBM 
 
---uname output---
Linux s38lp65 4.4.0-36-generic #55-Ubuntu SMP Thu Aug 11 18:05:09 UTC 2016 
s390x s390x s390x GNU/Linux
 
Machine Type = z13 LPAR 
 
---System Hang---
 System is frozen. No error, no dump, the system needs to be reloaded.
 
---Debugger---
A debugger is not configured
 
---Steps to Reproduce---
 1. install a system with encrypted swap partition. This can be done using the 
installer or via manual updates to /etc/fstab and /etc/crypttab.

2. Verify encrypted swap partition exists
 cryptsetup status kvmibm-swap
/dev/mapper/kvmibm-swap is active and is in use.
  type:    PLAIN
  cipher:  aes-xts-plain64:sha256
  keysize: 256 bits
  device:  /dev/dasda2
  offset:  0 sectors
  size:    8388672 sectors
  mode:    read/write

3. force swapping
this can be done by a command like this (if the system has 8GB memory)
dd if=/dev/zero of=/dev/null ibs=16k obs=8G count=2MB
 
Stack trace output:
 no
 
Oops output:
 no
 
System Dump Location:
 
 
*Additional Instructions for Bernd-Rainer Bresser/Germany/IBM, Wen Yi AG 
Gao/China/IBM: 
-Attach sysctl -a output output to the bug.

== Comment: #1 - Bernd-Rainer Bresser <bress...@de.ibm.com> - 2016-12-05 
04:33:24 ==
- the problem was originally found on KVM for IBM z 1.1.3
- test on Ubuntu 16.04.1 showed the same issue here
- on KVM for IBM z 1.1.3 the problem could be solved/circumvented by reverting
       commit 564e81a57f9788b1475127012e0fd44e9049e342
      Author: Tetsuo Handa <penguin-ker...@i-love.sakura.ne.jp>
      Date:   Fri Feb 5 15:36:30 2016 -0800
            mm, vmstat: fix wrong WQ sleep when memory reclaim doesn't make any 
progress

** Affects: linux (Ubuntu)
     Importance: Undecided
     Assignee: Skipper Bug Screeners (skipper-screen-team)
         Status: New


** Tags: architecture-s39064 bugnameltc-149525 severity-critical 
targetmilestone-inin---

** Tags added: architecture-s39064 bugnameltc-149525 severity-critical
targetmilestone-inin---

** Changed in: ubuntu
     Assignee: (unassigned) => Skipper Bug Screeners (skipper-screen-team)

** Package changed: ubuntu => linux (Ubuntu)

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https://bugs.launchpad.net/bugs/1647400

Title:
  system freeze when swapping to encrypted swap partition

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