Thanks for confirming. I sent a bug report.
> Date: Thu, 6 Dec 2012 10:44:27 +0530
> From: Vineet Naik <naikvin@gmail.com>
> Cc: help-gnu-emacs@gnu.org
>It's a bug. Please report it with "M-x report-emacs-bug RET".
> 1. start emacs with "emacs -Q" as you mentioned,
> 2. Open any file having multiple lines of text/code and try
> using C-p to move up a line. This works as expected.
> 3. enable global-linum-mode
> 4. Try it again. C-p moves two lines up
Thanks.