From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756848Ab1BAPCl (ORCPT ); Tue, 1 Feb 2011 10:02:41 -0500 Received: from e38.co.us.ibm.com ([32.97.110.159]:44033 "EHLO e38.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753538Ab1BAPCk (ORCPT ); Tue, 1 Feb 2011 10:02:40 -0500 Subject: Re: [RFC][PATCH 5/6] teach smaps_pte_range() about THP pmds From: Dave Hansen To: Johannes Weiner Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michael J Wolf , Andrea Arcangeli In-Reply-To: <20110201101111.GK19534@cmpxchg.org> References: <20110201003357.D6F0BE0D@kernel> <20110201003403.736A24DF@kernel> <20110201101111.GK19534@cmpxchg.org> Content-Type: text/plain; charset="ANSI_X3.4-1968" Date: Tue, 01 Feb 2011 07:02:30 -0800 Message-ID: <1296572550.27022.2862.camel@nimitz> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2011-02-01 at 11:11 +0100, Johannes Weiner wrote: > On Mon, Jan 31, 2011 at 04:34:03PM -0800, Dave Hansen wrote: > > + if (pmd_trans_huge(*pmd)) { > > + if (pmd_trans_splitting(*pmd)) { > > + spin_unlock(&walk->mm->page_table_lock); > > + wait_split_huge_page(vma->anon_vma, pmd); > > + spin_lock(&walk->mm->page_table_lock); > > + goto normal_ptes; > > + } > > + smaps_pte_entry(*(pte_t *)pmd, addr, HPAGE_SIZE, walk); > > + return 0; > > + } > > +normal_ptes: > > split_huge_page_pmd(walk->mm, pmd); > > This line can go away now...? I did this because I was unsure what keeps khugepaged away from the newly-split ptes between the wait_split_huge_page() and the reacquisition of the mm->page_table_lock. mmap_sem, perhaps? Looking at follow_page() and some of the other wait_split_huge_page(), it looks like this is unnecessary. -- Dave