Comment 0 for bug 1607894

== Comment: #0 - NAVEED A. UPPINANGADY SALIH - 2016-07-01 02:41:07 ==
---Problem Description---
Unable to analyse vmcore/kernel dumpfile generated by 4.4.0-29-generic kernel with ddeb kernel debuginfo available in http://ddebs.ubuntu.com/pool/main/l/linux/

http://ddebs.ubuntu.com/pool/main/l/linux/linux-image-4.4.0-29-generic-dbgsym_4.4.0-29.48_ppc64el.ddeb

---uname output---
 4.4.0-29-generic #48~14.04.1-Ubuntu SMP Wed Jun 29 19:55:03 UTC 2016 ppc64le ppc64le ppc64le GNU/Linux

Machine Type = model : 8247-22L machine : PowerNV 8247-22L

---Steps to Reproduce---
 # crash /usr/lib/debug/boot/vmlinux-4.4.0-29-generic /var/crash/201606300840/dump.201606300840
crash 7.0.3
...
This GDB was configured as "powerpc64le-unknown-linux-gnu"...

crash: invalid kernel virtual address: 61c2555c09c17994 type: "possible"
WARNING: cannot read cpu_possible_map
crash: invalid kernel virtual address: 8a0f6ddee20c4116 type: "present"
WARNING: cannot read cpu_present_map
crash: invalid kernel virtual address: 5a09344e320a1886 type: "online"
WARNING: cannot read cpu_online_map
WARNING: cannot read linux_banner string
crash: /usr/lib/debug/boot/vmlinux-4.4.0-29-generic and /var/crash/201606300840/dump.201606300840 do not match!

Userspace rpm: linux-image-4.4.0-29-generic-dbgsym_4.4.0-29.48_ppc64el.ddeb

== Comment: #5 - Naresh Bannoth - 2016-07-27 04:12:09 ==

The Latest kernel I am having is as follows

root@ltcalpine-lp6:~# uname -a
Linux ltcalpine-lp6 4.4.0-31-generic #50~14.04.1-Ubuntu SMP Wed Jul 13 01:03:56 UTC 2016 ppc64le ppc64le ppc64le GNU/Linux
root@ltcalpine-lp6:~#

====>>> the issue same as posted originally.

...
This GDB was configured as "powerpc64le-unknown-linux-gnu"...

crash: invalid kernel virtual address: 61c2555c09c17994 type: "possible"
WARNING: cannot read cpu_possible_map
crash: invalid kernel virtual address: 8a0f6ddee20c4116 type: "present"
WARNING: cannot read cpu_present_map
crash: invalid kernel virtual address: 5a09344e320a1886 type: "online"
WARNING: cannot read cpu_online_map
WARNING: cannot read linux_banner string
crash: /usr/lib/debug/boot/vmlinux-4.4.0-31-generic and /var/crash/201607270248/dump.201607270248 do not match!

== Comment: #6 - Hari Krishna Bathini - 2016-07-28 11:49:31 ==
The kernel is compiled with gcc version 4.8.4 while the vmlinux pulled
from http://ddebs.ubuntu.com/pool/main/l/linux/ is compiled with gcc
version 5.3.1 which is the source of the issue.

 Resolved this by pulling the kernel debug symbols package from:

  deb http://ddebs.ubuntu.com/ -updates main

which indeed has the vmlinux compiled with gcc version 4.8.4.
But I got this error:

  crash: invalid structure member offset: module_num_symtab
         FILE: kernel.c LINE: 3049 FUNCTION: module_init()

after the update owning to couple of missing patches listed below:

  commit 6f1f78e33474d00d5f261d7ed9d835c558b34d61
  Author: Dave Anderson <email address hidden>
  Date: Wed Jan 20 09:56:36 2016 -0500

    Fix for the changes made to the kernel module structure introduced by
    this kernel commit for Linux 4.5 and later kernels:

      commit 7523e4dc5057e157212b4741abd6256e03404cf1
      module: use a structure to encapsulate layout.

    Without the patch, the crash session fails during initialization
    with the error message: "crash: invalid structure member offset:
    module_init_text_size".
    (<email address hidden>)

  commit 098cdab16dfa6a85e9dad2cad604dee14ee15f66
  Author: Dave Anderson <email address hidden>
  Date: Fri Feb 12 14:32:53 2016 -0500

    Fix for the changes made to the kernel module structure introduced by
    this kernel commit for Linux 4.5 and later kernels:

      commit 8244062ef1e54502ef55f54cced659913f244c3e
      modules: fix longstanding /proc/kallsyms vs module insertion race.

    Without the patch, the crash session fails during initialization
    with the error message: "crash: invalid structure member offset:
    module_num_symtab".
    (<email address hidden>)

Applying the above patches on top of crash tool version 7.0.3-3ubuntu4.4,
was able to analyze the dump. The patches apply cleanly..

Thanks
Hari

== Comment: #8 - Naresh Bannoth - 2016-07-29 06:59:23 ==
Verified with 4.4.0-31-generic kernel.
on Applying the patches mentioned in the #C 6, it is working fine.
I took the Compiled Binary attached in the BUG and able to analyse the Dumpfile without any issues.

Thanks
Naresh

== Comment: #9 - Hari Krishna Bathini - 2016-07-29 07:47:25 ==

To sum this up, two things to make this work:

1. Install debug symbols package from here

    deb http://ddebs.ubuntu.com/ trusty main restricted universe multiverse
    deb http://ddebs.ubuntu.com/ trusty-security main restricted universe multiverse
    deb http://ddebs.ubuntu.com/ trusty-updates main restricted universe multiverse
    deb http://ddebs.ubuntu.com/ trusty-proposed main restricted universe multiverse

instead of http://ddebs.ubuntu.com/pool/main/l/linux/ as the gcc versions don't match.

2. Use a crash binary that has the upstream patches 6f1f78 & 098cda

Thanks
Hari