Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161413AbWKVAop (ORCPT ); Tue, 21 Nov 2006 19:44:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1031390AbWKVAop (ORCPT ); Tue, 21 Nov 2006 19:44:45 -0500 Received: from smtp.osdl.org ([65.172.181.25]:31384 "EHLO smtp.osdl.org") by vger.kernel.org with ESMTP id S1031385AbWKVAoo (ORCPT ); Tue, 21 Nov 2006 19:44:44 -0500 Date: Tue, 21 Nov 2006 16:44:20 -0800 (PST) From: Linus Torvalds To: Mel Gorman cc: Christoph Lameter , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/11] Add __GFP_MOVABLE flag and update callers In-Reply-To: Message-ID: References: <20061121225022.11710.72178.sendpatchset@skynet.skynet.ie> <20061121225042.11710.15200.sendpatchset@skynet.skynet.ie> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1502 Lines: 35 On Tue, 21 Nov 2006, Mel Gorman wrote: > > On Tue, 21 Nov 2006, Christoph Lameter wrote: > > > Are GFP_HIGHUSER allocations always movable? It would reduce the size of > > the patch if this would be added to GFP_HIGHUSER. > > > > No, they aren't. Page tables allocated with HIGHPTE are currently not movable > for example. A number of drivers (infiniband for example) also use > __GFP_HIGHMEM that are not movable. It might make sense to just use another GFP_HIGHxyzzy #define for the non-movable HIGHMEM users. There's probably much fewer of those, and their behaviour obviously is very different from the traditional GFP_HIGHUSER pages (ie page cache and anonymous user mappings). So you could literally use "GFP_HIGHPTE" for the PTE mappings, and that would in fact even simplify some of the users (ie it would allow moving the #ifdef CONFIG_HIGHPTE check from the code to ). Similarly for any other non-movable things, no? So then we'd just make GFP_HIGHUSER implicitly mean "movable". It could be nice if GFP_USER would do the same, but I guess we have too many of those around to verify (although _most_ of those are probably kmalloc, and kmalloc would obviously better strip away the __GFP_MOVABLE bit anyway). Linus - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/