From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 11 Jun 2008 13:11:08 -0700 From: Andrew Morton Subject: Re: [v4][PATCH 2/2] fix large pages in pagemap Message-Id: <20080611131108.61389481.akpm@linux-foundation.org> In-Reply-To: <1213213980.20045.116.camel@calx> References: <20080611180228.12987026@kernel> <20080611180230.7459973B@kernel> <20080611123724.3a79ea61.akpm@linux-foundation.org> <1213213980.20045.116.camel@calx> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Matt Mackall Cc: dave@linux.vnet.ibm.com, hans.rosenfeld@amd.com, linux-mm@kvack.org, hugh@veritas.com, Rik van Riel List-ID: On Wed, 11 Jun 2008 14:53:00 -0500 Matt Mackall wrote: > [adding Hugh to the cc:] > > On Wed, 2008-06-11 at 12:37 -0700, Andrew Morton wrote: > > On Wed, 11 Jun 2008 11:02:31 -0700 > > Dave Hansen wrote: > > > > > > > > We were walking right into huge page areas in the pagemap > > > walker, and calling the pmds pmd_bad() and clearing them. > > > > > > That leaked huge pages. Bad. > > > > > > This patch at least works around that for now. It ignores > > > huge pages in the pagemap walker for the time being, and > > > won't leak those pages. > > > > > > > I don't get it. Why can't we just stick a > > > > if (pmd_huge(pmd)) > > continue; > > > > into pagemap_pte_range()? Or something like that. > > That's certainly what you'd hope to be able to do, yes. > > If I recall the earlier discussion, some arches with huge pages can only > identify them via a VMA. Obviously, any arch with hardware that walks > our pagetables directly must be able to identify huge pages directly > from those tables, but I think PPC and a couple others that don't have > hardware TLB fill fail to store such a bit in the tables at all. Really? There already a couple of pmd_huge() tests in mm/memory.c and Rik's access_process_vm-device-memory-infrastructure.patch adds another one. -- 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