[Crash-utility] crash: invalid kernel virtual address: 0 type: "memory section"

[Ilya Dryomov]

On Mon, Jan 5, 2015 at 7:02 PM, Ilya Dryomov <idryomov at redhat.com> wrote:
> On Mon, Jan 5, 2015 at 6:49 PM, Dave Anderson <anderson at redhat.com> wrote:
>>
>>
>> Just for sanity's sake, try this:
>>
>>   $ ./crash --minimal ../ddeb/usr/lib/debug/boot/vmlinux-3.13.0-39-generic ../dump.201412280256
>>
>> and see if you can read the linux_banner string successfully.  For example, using
>> my sample 3.13 kernel:
>>
>>   $ crash --minimal 3.13.0-0.rc1.git2.1.fc20_SLAB/vmlinux.gz 3.13.0-0.rc1.git2.1.fc20_SLAB/vmcore_c_d31
>>
>>   crash 7.0.9
>>   Copyright (C) 2002-2014  Red Hat, Inc.
>>   Copyright (C) 2004, 2005, 2006, 2010  IBM Corporation
>>   Copyright (C) 1999-2006  Hewlett-Packard Co
>>   Copyright (C) 2005, 2006, 2011, 2012  Fujitsu Limited
>>   Copyright (C) 2006, 2007  VA Linux Systems Japan K.K.
>>   Copyright (C) 2005, 2011  NEC Corporation
>>   Copyright (C) 1999, 2002, 2007  Silicon Graphics, Inc.
>>   Copyright (C) 1999, 2000, 2001, 2002  Mission Critical Linux, Inc.
>>   This program is free software, covered by the GNU General Public License,
>>   and you are welcome to change it and/or distribute copies of it under
>>   certain conditions.  Enter "help copying" to see the conditions.
>>   This program has absolutely no warranty.  Enter "help warranty" for details.
>>
>>   GNU gdb (GDB) 7.6
>>   Copyright (C) 2013 Free Software Foundation, Inc.
>>   License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
>>   This is free software: you are free to change and redistribute it.
>>   There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
>>   and "show warranty" for details.
>>   This GDB was configured as "x86_64-unknown-linux-gnu"...
>>
>>   NOTE: minimal mode commands: log, dis, rd, sym, eval, set, extend and exit
>>
>>   crash> rd -a linux_banner
>>   ffffffff818000c0:  Linux version 3.13.0-0.rc1.git2.1.fc20.x86_64 (root at hp-xw455
>>   ffffffff818000fc:  0-02.ml3.eng.bos.redhat.com) (gcc version 4.8.1 20130814 (Re
>>   ffffffff81800138:  d Hat 4.8.1-6) (GCC) ) #1 SMP Tue Nov 26 14:42:45 EST 2013
>>   crash>
>>
>> And then try reading other stuff, most notably the __per_cpu_offset[] array,
>> like this:
>>
>>   crash> rd __per_cpu_offset 256
>
> Attached - __per_cpu_offset seems busted.

OK, so the banner read with crash is

ffffffff818000a0:  Linux version 3.13.0-39-generic (buildd at brownie) (gcc versio
ffffffff818000dc:  n 4.6.3 (Ubuntu/Linaro 4.6.3-1ubuntu5) ) #66~precise1-Ubuntu
ffffffff81800118:   SMP Wed Oct 29 09:56:49 UTC 2014 (Ubuntu 3.13.0-39.66~preci
ffffffff81800154:  se1-generic 3.13.11.8)

whereas the banner from vmlinux-3.13.0-39-generic is

0a000a0: 4c69 6e75 7820 7665 7273 696f 6e20 332e  Linux version 3.
0a000b0: 3133 2e30 2d33 392d 6765 6e65 7269 6320  13.0-39-generic
0a000c0: 2862 7569 6c64 6440 746f 796f 6c29 2028  (buildd at toyol) (
0a000d0: 6763 6320 7665 7273 696f 6e20 342e 382e  gcc version 4.8.
0a000e0: 3220 2855 6275 6e74 7520 342e 382e 322d  2 (Ubuntu 4.8.2-
0a000f0: 3139 7562 756e 7475 3129 2029 2023 3636  19ubuntu1) ) #66
0a00100: 2d55 6275 6e74 7520 534d 5020 5475 6520  -Ubuntu SMP Tue
0a00110: 4f63 7420 3238 2031 333a 3330 3a32 3720  Oct 28 13:30:27
0a00120: 5554 4320 3230 3134 2028 5562 756e 7475  UTC 2014 (Ubuntu
0a00130: 2033 2e31 332e 302d 3339 2e36 362d 6765   3.13.0-39.66-ge
0a00140: 6e65 7269 6320 332e 3133 2e31 312e 3829  neric 3.13.11.8)

I guess I need to try to hunt down that exact vmlinux.  Sigh.

Thanks,

                Ilya