linux-kernel - kdump/kexec vmcore size doubles each time

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Date:	Thu, 19 Jul 2012 15:08:44 -0700 (PDT)
From:	joe shmoe <joeshmoeypeter@...oo.com>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: kdump/kexec vmcore size doubles each time

Hi,
I am trying to configure kexec/kdump on 2.6.35-14. 

$> kexec --version
kexec-tools-testing 20080330 released 30th March 2007

I did manage to configure kdump to use raw device (/dev/sda7) for saving the dump from within the initrd.

When the production kernel boots, it copies core from /dev/sda7 to /var/crash/ path.
I see that the size of data copied over from /dev/sda7 to /var/crash almost doubles with every crash (370MB to 620MB to 1.2 GB to 2.1GB). 

The size returns back to normal, should there be a "normal" reboot cycle anytime. After that every subsequent crash again doubles the size. This is very baffling. 

On a related note, I wanted to understand if there are any known issues with having swap device as a dump location. Does kdump start 
early enough to ensure that vmcore can be safely copied off swap 
/dev/sda7 and THEN mkswap/swapon commands set up the swap space?

Thanks much.
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