From mboxrd@z Thu Jan 1 00:00:00 1970 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Subject: RE: [RFC/PATCH] pfn_valid() more generic : intro[0/2] Date: Tue, 5 Oct 2004 23:33:28 -0700 Message-ID: From: "Luck, Tony" Sender: owner-linux-mm@kvack.org Return-Path: To: Hiroyuki KAMEZAWA , LinuxIA64 Cc: linux-mm List-ID: >ia64's ia64_pfn_valid() uses get_user() for checking whether a >page struct is available or not. I think this is an irregular >implementation and following patches >are a more generic replacement, careful_pfn_valid(). It uses 2 >level table. It is odd ... but a somewhat convenient way to make check whether the page struct exists, while handling the fault if it is in an area of virtual mem_map that doesn't exist. I think that in practice we rarely call it with a pfn that generates a fault (except in error paths). How big will the pfn_validmap[] be for a very sparse physical space like SGI Altix? I'm not sure I see how PFN_VALID_MAPSHIFT is generated for each system. Why do we need a loop when looking in the 2nd level? Can't the entry from the 1st level point us to the right place? -Tony -- 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