From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Thu, 31 Jul 2003 11:35:49 +0100 (IST) From: Mel Gorman Subject: Re: do_wp_page In-Reply-To: Message-ID: References: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: "Raghu R. Arur" Cc: linux-mm@kvack.org List-ID: On Wed, 30 Jul 2003, Raghu R. Arur wrote: > In do_wp_page of 2.4.19 why is the rss value of address space > incremented only when the old_page ( the page on which the process faults > due to write protection) is a reserved page. The page been faulted is a copy-on-write page so it's shared between more than one process. If the process had 10 pages present before the fault, it'll still will have 10 pages after the fault so the rss is not updated. If the PageReserved() is true, it's the system wide ZERO_PAGE (PG_reserved is set at boot time) and as far as I know, the system wide zero page is the only one that can be mapped into a process with that bit set. If you look at do_no_page(), you'll see that the zero page is not accounted for in the RSS. If a COW takes place on the zero page, the process will be using one more page than it was previously so rss++. -- Mel Gorman -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: aart@kvack.org