ISST-LTE:pVM:roselp2:ubuntu 16.10: crash failed to check vmcore of 4.8 kernel

== Comment: #0 - Ping Tian Han - 2016-09-22 03:05:36 ==
---Problem Description---
crash cannot check vmcore of 4.8 kernel.

Then when trying to check the core with crash:

% sudo crash /usr/lib/debug/boot/vmlinux-4.8.0-14-generic /var/crash/201609212349/vmcore.201609212349

crash 7.1.5
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please wait... (gathering kmem slab cache data)
crash: invalid kernel virtual address: 7aa9fe01000000 type: "pmd page"

---uname output---
Linux roselp2 4.8.0-14-generic #15-Ubuntu SMP Tue Sep 20 21:59:33 UTC 2016 ppc64le ppc64le ppc64le GNU/Linux

Machine Type = IBM,8286-42A, lpar

---Steps to Reproduce---
 1. install 4.8 kernel
2. trigger kdump to get vmcore
3. check the vmcore with crash

== Comment: #8 - Hari Krishna Bathini - 2016-09-24 14:12:23 ==
The below commit is needed for vtop address translation to succeed

  commit 182914debbb9a2671ef644027fedd339aa9c80e0
  Author: Dave Anderson <email address hidden>
  Date: Fri Sep 23 09:09:15 2016 -0400

    With the introduction of radix MMU in Power ISA 3.0, there are
    changes in kernel page table management accommodating it. This patch
    series makes appropriate changes here to work for such kernels.
    Also, this series fixes a few bugs along the way:

      ppc64: fix vtop page translation for 4K pages
      ppc64: Use kernel terminology for each level in 4-level page table
      ppc64/book3s: address changes in kernel v4.5
      ppc64/book3s: address change in page flags for PowerISA v3.0
      ppc64: use physical addresses and unfold pud for 64K page size
      ppc64/book3s: support big endian Linux page tables

    The patches are needed for Linux v4.5 and later kernels on all
    ppc64 hardware.
    (<email address hidden>)
--

Also, the below commit is needed

  commit 8ceb1ac628bf6a0a7f0bbfff030ec93081bca4cd
  Author: Dave Anderson <email address hidden>
  Date: Mon May 23 11:23:01 2016 -0400

    Fix for Linux commit 0139aa7b7fa12ceef095d99dc36606a5b10ab83a, which
    renamed the page._count member to page._refcount. Without the patch,
    certain "kmem" commands fail with the "kmem: invalid structure member
    offset: page_count".
    (<email address hidden>)

Thanks
Hari