From mboxrd@z Thu Jan  1 00:00:00 1970
From: Mukesh Rathor <mukesh.rathor@oracle.com>
Subject: struct page_info
Date: Thu, 23 Apr 2009 20:15:25 -0700
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Hi,
I'm trying to figure out all the incarnations of a page. That led me to
page_info{}. Now, looking at it, the shadow page is confusing.

	/* Page is in use: ((count_info & PGC_count_mask) != 0).  */
	..

         /* Page is in use as a shadow: count_info == 0. */
	..
	/* Page is on a free list: ((count_info & PGC_count_mask) == 0). */
	..

If count_info == 0, and it implies shadow page, how's that different
from an unallocated page which also would've count_info=0 I presume?

Also, if "Page is on a free list:", I assume one of the PGC_ fields would
be set?


thanks,
Mukesh