[Crash-utility] crash seek error, failed to read vmcore file

[Pavan Naregundi]

On Tue, 2010-04-20 at 09:14 -0400, Dave Anderson wrote:
> ----- "Pavan Naregundi" <pavan at linux.vnet.ibm.com> wrote:
> 
> The cause for seek errors depends upon the type
> of dumpfile.
> 
> You didn't mention which type of dumpfile the vmcore
> is, so I'll presume that it's either an ELF-format
> kdump or a compressed kdump created by makedumpfile.
> 
> So presuming that it's a compressed kdump, the seek error 
> most likely comes from here in read_diskdump() in diskdump.c:
> 
>         if ((pfn >= dd->header->max_mapnr) || !page_is_ram(pfn))
>                 return SEEK_ERROR;
> 
> where the requested physical address pfn values are larger
> than the max_mapnr value advertised in the header.
> 
> When you do any "crash -d# ...", the dumpfile header will
> be dumped first.  What does that show?
> 
> Dave


Dave,

Dumpfile is compressed kdump created by makedumpfile.

header shows the following values: 
max_mapnr: 32768
block_shift: 16

Yes. Adding some debug printf's shows me that (pfn >=
dd->header->max_mapnr) fails. 

For example: in the first seek error,
crash: seek error: kernel virtual address: c0000000af715480  type:
"kmem_cache buffer"

paddr: af715480 => pfn=44913

crash -d8 log: http://pastebin.com/qrCvyPfR

Thanks..Pavan