From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx157.postini.com [74.125.245.157]) by kanga.kvack.org (Postfix) with SMTP id EAAF06B00A2 for ; Mon, 16 Jan 2012 12:20:01 -0500 (EST) Message-ID: <4F145BE7.1060802@ah.jp.nec.com> Date: Mon, 16 Jan 2012 12:18:31 -0500 From: Naoya Horiguchi MIME-Version: 1.0 Subject: Re: [PATCH 1/6] pagemap: avoid splitting thp when reading /proc/pid/pagemap Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrea Arcangeli Cc: Naoya Horiguchi , linux-mm@kvack.org, Andrew Morton , David Rientjes , Andi Kleen , Wu Fengguang , KOSAKI Motohiro , KAMEZAWA Hiroyuki , linux-kernel@vger.kernel.org On Sat, Jan 14, 2012 at 06:00:26PM +0100, Andrea Arcangeli wrote: > On Thu, Jan 12, 2012 at 02:34:53PM -0500, Naoya Horiguchi wrote: > > + if (pmd_trans_splitting(*pmd)) { > > + spin_unlock(&walk->mm->page_table_lock); > > + wait_split_huge_page(vma->anon_vma, pmd); > > + } else { > > + for (; addr != end; addr += PAGE_SIZE) { > > + unsigned long offset = (addr & ~PAGEMAP_WALK_MASK) > > + >> PAGE_SHIFT; > > + pfn = thp_pte_to_pagemap_entry(*(pte_t *)pmd, > > + offset); > > What is this that then morphs into a pme (which still has a cast > inside its creation)? thp_pte_to_pagemap_entry don't seem to be passed > ptes too. The only case where it is valid to do a cast like that is > when a function is used by both ptes sand pmds and the code tends to > work for both with minimal modification to differentiate the two > cases. Considering the function that gets the cast is called thp_ this > is hardly the case here. Agreed. > Why don't you pass the pmd and then do "if (pmd_present(pmd)) > page_to_pfn(pmd_page(pmd)) ? What's the argument for the cast. I'm > just reviewing this series and maybe it was covered in previous > versions. OK, I can do this by introducing pmd_pte as you commented in another email. > I don't get this pme thing for something as trivial as above that > shouldn't require any cast at all. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org