** Description changed:

+ SRU Justification:
+ 
+ Impact: An upstream change in 2.6.31 tried to simplify the conditions of
+ having the lazy mmu mode in paravirt disabled. With that in mind several
+ instances where the lazy mmu mode was disabled explicitly have been
+ removed. However it was found that from k(un)map_atomic there is a
+ chance to cause an oops.
+ 
+ Fix: The following patch has been sent upstream (currently it is only in
+ the -mm tree and linux-next). It has been tested to fix the problem on
+ 2.6.38. The specific symptom seen, seems to have come up since 2.6.37,
+ however the lines of code that are re-introduced have been removed since
+ 2.6.31.
+ 
+ Testcase: Trying to do forks under high load should trigger the issue
+ (at least on 2.6.37+ kernels)
+ 
+ --
+ 
  I'm filing this bug in response to threads at [1] and [2].  From those 
threads, we see reported that
-  * the instance becomes unavailable.
-  * the issue is reported  to have to have been seen multiple different 
instance types
-     [TYPE: m2.xlarge, m1.large, t1.micro  ( all types have hung ) ]
-  * at [2] there is BUG_ON output pointing at swap, but I would not have 
expected a user of an m2.xlarge to be using swap, so I personally suspect that 
that hang is different.
- 
+  * the instance becomes unavailable.
+  * the issue is reported  to have to have been seen multiple different 
instance types
+     [TYPE: m2.xlarge, m1.large, t1.micro  ( all types have hung ) ]
+  * at [2] there is BUG_ON output pointing at swap, but I would not have 
expected a user of an m2.xlarge to be using swap, so I personally suspect that 
that hang is different.
  
  [1] 
http://groups.google.com/group/ec2ubuntu/browse_frm/thread/57ff20c6370f7bb9
  [2] https://forums.aws.amazon.com/message.jspa?messageID=262300
  
  ProblemType: Bug
  DistroRelease: Ubuntu 11.04
  Package: linux-image-2.6.38-8-virtual 2.6.38-8.42
  ProcVersionSignature: User Name 2.6.38-8.42-virtual 2.6.38.2
  Uname: Linux 2.6.38-8-virtual x86_64
  AlsaDevices:
-  total 0
-  crw------- 1 root root 116,  1 2011-09-19 17:02 seq
-  crw------- 1 root root 116, 33 2011-09-19 17:02 timer
+  total 0
+  crw------- 1 root root 116,  1 2011-09-19 17:02 seq
+  crw------- 1 root root 116, 33 2011-09-19 17:02 timer
  AplayDevices: Error: [Errno 2] No such file or directory
  Architecture: amd64
  ArecordDevices: Error: [Errno 2] No such file or directory
  CurrentDmesg: [   16.930013] eth0: no IPv6 routers present
  Date: Mon Sep 19 17:23:59 2011
  Ec2AMI: ami-1aad5273
  Ec2AMIManifest: (unknown)
  Ec2AvailabilityZone: us-east-1c
  Ec2InstanceType: t1.micro
  Ec2Kernel: aki-427d952b
  Ec2Ramdisk: unavailable
  Lspci:
-  
+ 
  Lsusb: Error: command ['lsusb'] failed with exit code 1:
  ProcEnviron:
-  PATH=(custom, user)
-  LANG=en_US.UTF-8
-  SHELL=/bin/bash
+  PATH=(custom, user)
+  LANG=en_US.UTF-8
+  SHELL=/bin/bash
  ProcKernelCmdLine: root=LABEL=uec-rootfs ro console=hvc0
  ProcModules: acpiphp 24097 0 - Live 0x0000000000000000
  SourcePackage: linux
  UpgradeStatus: No upgrade log present (probably fresh install)

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https://bugs.launchpad.net/bugs/854050

Title:
  BUG at /build/buildd/linux-2.6.38/mm/swapfile.c:255

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