From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Mon, 13 Nov 2006 17:22:46 +1100 From: 'David Gibson' Subject: Re: [hugepage] Fix unmap_and_free_vma backout path Message-ID: <20061113062246.GH27042@localhost.localdomain> References: <20061113055711.GF27042@localhost.localdomain> <000101c706e9$726c1120$a081030a@amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <000101c706e9$726c1120$a081030a@amr.corp.intel.com> Sender: owner-linux-mm@kvack.org Return-Path: To: "Chen, Kenneth W" Cc: Christoph Lameter , Andrew Morton , Hugh Dickins , bill.irwin@oracle.com, Adam Litke , linux-mm@kvack.org List-ID: On Sun, Nov 12, 2006 at 10:03:31PM -0800, Chen, Kenneth W wrote: > David Gibson wrote on Sunday, November 12, 2006 9:57 PM > > On Sun, Nov 12, 2006 at 09:29:48PM -0800, Christoph Lameter wrote: > > > On Mon, 13 Nov 2006, 'David Gibson' wrote: > > > > > > > This may not be all we want. Even with this patch, performing such a > > > > failing map on to of an existing mapping will clobber (unmap) that > > > > pre-existing mapping. This is in contrast to the analogous situation > > > > with normal page mappings - mapping on top with a misaligned offset > > > > will fail early enough not to clobber the pre-existing mapping. > > > > > > Then it is best to check the huge page alignment at the > > > same place as regular alignment. > > > > Probably, yes, although it's yet another "if (hugepage) > > specialcase()". But I still think we want the above patch as well. > > It will make sure we correctly back out from any other possible > > failure cases in hugetlbfs_file_mmap() - ones I haven't thought of, or > > which get added later. > > > Something like this? I haven't tested it yet. But looks plausible > because we already have if is_file_hugepages() in the generic path. Um.. if you're going to test pgoff here, you should also test the address. Oh, and that point is too late to catch MAP_FIXED mappings. I was thinking more of testing it in the same place we test the page alignment for normal mappings. Except that's in arch code. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson -- 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