From mboxrd@z Thu Jan 1 00:00:00 1970 In-reply-to: <20070307082755.GA25733@elte.hu> (message from Ingo Molnar on Wed, 7 Mar 2007 09:27:55 +0100) Subject: Re: [patch 4/6] mm: merge populate and nopage into fault (fixes nonlinear) References: <20070221023656.6306.246.sendpatchset@linux.site> <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> Message-Id: From: Miklos Szeredi Date: Wed, 07 Mar 2007 09:38:34 +0100 Sender: owner-linux-mm@kvack.org Return-Path: To: mingo@elte.hu Cc: npiggin@suse.de, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, benh@kernel.crashing.org List-ID: > > If it doesn't look very impressive, it could be because it leaves all > > the old crud around for backwards compatibility (the worst offenders > > are removed in patch 6/6). > > > > If you look at the patchset as a whole, it removes about 250 lines, > > mostly of (non trivial) duplicated code in filemap.c memory.c shmem.c > > fremap.c, that is nonlinear pages specific and doesn't get anywhere > > near the testing that the linear fault path does. > > > > A minimal fix for nonlinear pages would have required changing all > > ->populate handlers, which I simply thought was not very productive > > considering the testing and coverage issues, and that I was going to > > rewrite the nonlinear path anyway. > > > > If you like, you can consider patches 1,2,3 as the fix, and ignore > > nonlinear (hey, it doesn't even bother checking truncate_count > > today!). > > > > Then 4,5,6 is the fault/nonlinear rewrite, take it or leave it. I > > thought you would have liked the patches... > > btw., if we decide that nonlinear isnt worth the continuing maintainance > pain, we could internally implement/emulate sys_remap_file_pages() via a > call to mremap() and essentially deprecate it, without breaking the ABI > - and remove all the nonlinear code. (This would split fremap areas into > separate vmas) That would make sense. Dirty page accounting doesn't work either on non-linear mappings, and I can't see how that could be fixed in any other way. Miklos -- 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