From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263198AbVFWIT2 (ORCPT ); Thu, 23 Jun 2005 04:19:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263055AbVFWIR2 (ORCPT ); Thu, 23 Jun 2005 04:17:28 -0400 Received: from smtp201.mail.sc5.yahoo.com ([216.136.129.91]:28791 "HELO smtp201.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S262622AbVFWHIA (ORCPT ); Thu, 23 Jun 2005 03:08:00 -0400 Message-ID: <42BA5FC8.9020501@yahoo.com.au> Date: Thu, 23 Jun 2005 17:07:52 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.6) Gecko/20050324 Debian/1.7.6-1 X-Accept-Language: en MIME-Version: 1.0 To: linux-kernel , Linux Memory Management CC: Hugh Dickins , Badari Pulavarty Subject: Re: [patch][rfc] 4/5: remap ZERO_PAGE mappings References: <42BA5F37.6070405@yahoo.com.au> <42BA5F5C.3080101@yahoo.com.au> <42BA5F7B.30904@yahoo.com.au> <42BA5FA8.7080905@yahoo.com.au> In-Reply-To: <42BA5FA8.7080905@yahoo.com.au> Content-Type: multipart/mixed; boundary="------------050204080603020303060408" Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This is a multi-part message in MIME format. --------------050204080603020303060408 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit 4/5 --------------050204080603020303060408 Content-Type: text/plain; name="mm-remap-ZERO_PAGE-mappings.patch" Content-Transfer-Encoding: 7bit Content-Disposition: inline; filename="mm-remap-ZERO_PAGE-mappings.patch" Remap ZERO_PAGE ptes when remapping memory. This is currently just an optimisation for MIPS, which is the only architecture with multiple zero pages - it now retains the mapping it needs for good cache performance, and as well do_wp_page is now able to always correctly detect and optimise zero page COW faults. In future, this becomes required in order to always be able to detect whether a pte points to a ZERO_PAGE using only the pte, vaddr pair. Signed-off-by: Nick Piggin Index: linux-2.6/mm/mremap.c =================================================================== --- linux-2.6.orig/mm/mremap.c +++ linux-2.6/mm/mremap.c @@ -141,6 +141,10 @@ move_one_page(struct vm_area_struct *vma if (dst) { pte_t pte; pte = ptep_clear_flush(vma, old_addr, src); + /* ZERO_PAGE can be dependant on virtual addr */ + if (pfn_valid(pte_pfn(pte)) && + pte_page(pte) == ZERO_PAGE(old_addr)) + pte = pte_wrprotect(mk_pte(ZERO_PAGE(new_addr), new_vma->vm_page_prot)); set_pte_at(mm, new_addr, dst, pte); } else error = -ENOMEM; --------------050204080603020303060408-- Send instant messages to your online friends http://au.messenger.yahoo.com