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

[Dave Anderson]

----- Original Message -----
> 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>


BTW, if you do this:

  $ strings ../ddeb/usr/lib/debug/boot/vmlinux-3.13.0-39-generic | grep "Linux version"
 
Do you see the same "Oct 29 09:56:49" build date as shown in the linux_banner string?
 
If that all matches up, then it seemingly points to a faulty dumpfile.

> >
> > 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.
> 
> Thanks,
> 
>                 Ilya

Right:

> crash> rd __per_cpu_offset 256
> ffffffff81d130e0:  0000000000000000 0000000000000000   ................
> ffffffff81d130f0:  0000000000000000 0000000000000000   ................
> ffffffff81d13100:  0000000000000000 0000000000000000   ................
> ffffffff81d13110:  0000000000000000 0000000000000000   ................
> ffffffff81d13120:  0000000000000000 0000000000000000   ................
> ffffffff81d13130:  0000000000000000 0000000000000000   ................
> ffffffff81d13140:  0000000000000000 0000000000000000   ................
> ffffffff81d13150:  0000000000000000 0000000000000000   ................
> ... [ cut ] ...
> ffffffff81d137e0:  0000003000000001 0000000100000000   ....0...........
> ffffffff81d137f0:  0000000100000000 ffff880417106100   .........a......
> ffffffff81d13800:  ffffffff81766240 0000000000000000   @bv.............
> ffffffff81d13810:  0000000000000010 0000000000000000   ................
> ffffffff81d13820:  0000000000000000 0000000000000000   ................
> ffffffff81d13830:  0000000000000000 0000000000000000   ................
> ffffffff81d13840:  0000000000000000 0000000000000000   ................
> ffffffff81d13850:  0000000000000000 0000000000000000   ................
> ffffffff81d13860:  000000000000000a 0000000000000078   ........x.......
> ffffffff81d13870:  0000000000400000 0000000a00000000   .. at .............
> ffffffff81d13880:  00000000ee6b2800 0000000100000001   .(k.............
> ffffffff81d13890:  0000000000000000 0000000000000000   ................
> ffffffff81d138a0:  0000000000000000 0000000000000000   ................
> ffffffff81d138b0:  0000000000000000 0000000000000000   ................
> ffffffff81d138c0:  0000000000000000 0000000000000000   ................
> ffffffff81d138d0:  0000000000000000 0000000000000000   ................

And given the above, the dumpfile is fairly useless except for whatever
you can get out of it with --minimal. 

Dave