From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH v2] mm: thp: Set the accessed flag for old pages on access fault. Date: Tue, 2 Oct 2012 15:01:04 -0700 Message-ID: <20121002150104.da57fa94.akpm@linux-foundation.org> References: <1349197151-19645-1-git-send-email-will.deacon@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1349197151-19645-1-git-send-email-will.deacon@arm.com> Sender: linux-kernel-owner@vger.kernel.org To: Will Deacon Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, mhocko@suse.cz, kirill@shutemov.name, Andrea Arcangeli , Chris Metcalf , Steve Capper List-Id: linux-arch.vger.kernel.org On Tue, 2 Oct 2012 17:59:11 +0100 Will Deacon wrote: > On x86 memory accesses to pages without the ACCESSED flag set result in the > ACCESSED flag being set automatically. With the ARM architecture a page access > fault is raised instead (and it will continue to be raised until the ACCESSED > flag is set for the appropriate PTE/PMD). > > For normal memory pages, handle_pte_fault will call pte_mkyoung (effectively > setting the ACCESSED flag). For transparent huge pages, pmd_mkyoung will only > be called for a write fault. > > This patch ensures that faults on transparent hugepages which do not result > in a CoW update the access flags for the faulting pmd. Alas, the code you're altering has changed so much in linux-next that I am reluctant to force this fix in there myself. Can you please redo/retest/resend? You can do that on 3.7-rc1 if you like, then we can feed this into -rc2. > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3524,7 +3524,8 @@ retry: > > barrier(); > if (pmd_trans_huge(orig_pmd)) { > - if (flags & FAULT_FLAG_WRITE && > + int dirty = flags & FAULT_FLAG_WRITE; `flags' is `unsigned int', so making `dirty' match that is nicer. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:53338 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932355Ab2JBWBG (ORCPT ); Tue, 2 Oct 2012 18:01:06 -0400 Date: Tue, 2 Oct 2012 15:01:04 -0700 From: Andrew Morton Subject: Re: [PATCH v2] mm: thp: Set the accessed flag for old pages on access fault. Message-ID: <20121002150104.da57fa94.akpm@linux-foundation.org> In-Reply-To: <1349197151-19645-1-git-send-email-will.deacon@arm.com> References: <1349197151-19645-1-git-send-email-will.deacon@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-arch-owner@vger.kernel.org List-ID: To: Will Deacon Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, mhocko@suse.cz, kirill@shutemov.name, Andrea Arcangeli , Chris Metcalf , Steve Capper Message-ID: <20121002220104.IwOLWDvoAIwfzXuP6yseqFElkO1ToThjn_XbB2Olxd8@z> On Tue, 2 Oct 2012 17:59:11 +0100 Will Deacon wrote: > On x86 memory accesses to pages without the ACCESSED flag set result in the > ACCESSED flag being set automatically. With the ARM architecture a page access > fault is raised instead (and it will continue to be raised until the ACCESSED > flag is set for the appropriate PTE/PMD). > > For normal memory pages, handle_pte_fault will call pte_mkyoung (effectively > setting the ACCESSED flag). For transparent huge pages, pmd_mkyoung will only > be called for a write fault. > > This patch ensures that faults on transparent hugepages which do not result > in a CoW update the access flags for the faulting pmd. Alas, the code you're altering has changed so much in linux-next that I am reluctant to force this fix in there myself. Can you please redo/retest/resend? You can do that on 3.7-rc1 if you like, then we can feed this into -rc2. > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -3524,7 +3524,8 @@ retry: > > barrier(); > if (pmd_trans_huge(orig_pmd)) { > - if (flags & FAULT_FLAG_WRITE && > + int dirty = flags & FAULT_FLAG_WRITE; `flags' is `unsigned int', so making `dirty' match that is nicer.