From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 7 Mar 2007 10:45:03 +0100 From: Nick Piggin Subject: Re: [patch 4/6] mm: merge populate and nopage into fault (fixes nonlinear) Message-ID: <20070307094503.GD8609@wotan.suse.de> References: <20070221023735.6306.83373.sendpatchset@linux.site> <20070306225101.f393632c.akpm@linux-foundation.org> <20070307070853.GB15877@wotan.suse.de> <20070307081948.GA9563@wotan.suse.de> <20070307082755.GA25733@elte.hu> <20070307004709.432ddf97.akpm@linux-foundation.org> <20070307010756.b31c8190.akpm@linux-foundation.org> <1173259942.6374.125.camel@twins> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1173259942.6374.125.camel@twins> Sender: owner-linux-mm@kvack.org Return-Path: To: Peter Zijlstra Cc: Andrew Morton , Miklos Szeredi , mingo@elte.hu, linux-mm@kvack.org, linux-kernel@vger.kernel.org, benh@kernel.crashing.org List-ID: On Wed, Mar 07, 2007 at 10:32:22AM +0100, Peter Zijlstra wrote: > On Wed, 2007-03-07 at 01:07 -0800, Andrew Morton wrote: > > On Wed, 07 Mar 2007 09:51:57 +0100 Miklos Szeredi wrote: > > > > > > > Dirty page accounting doesn't work either on > > > > > non-linear mappings > > > > > > > > It doesn't? Confused - these things don't have anything to do with each > > > > other do they? > > > > > > Look in page_mkclean(). Where does it handle non-linear mappings? > > > > > > > OK, I'd forgotten about that. It won't break dirty memory accounting, > > but it'll potentially break dirty memory balancing. > > > > If we have the wrong page (due to nonlinear), page_check_address() will > > fail and we'll leave the pte dirty. That puts us back to the pre-2.6.17 > > algorithms and I guess it'll break the msync guarantees. > > > > Peter, I thought we went through the nonlinear problem ages ago and decided > > it was OK? > > Can recollect as much, I modelled it after page_referenced() and can't > find any VM_NONLINEAR specific code in there either. > > Will have a hard look, but if its broken, then page_referenced if > equally broken it seems, which would make page reclaim funny in the > light of nonlinear mappings. page_referenced is just an heuristic, and it ignores nonlinear mappings and the page which will get filtered down to try_to_unmap. Page reclaim is already "funny" for nonlinear mappings, page_referenced is the least of its worries ;) It works, though. -- 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: email@kvack.org