From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrea Arcangeli Subject: Re: [PATCH v2] mm: thp: Set the accessed flag for old pages on access fault. Date: Tue, 2 Oct 2012 19:46:24 +0200 Message-ID: <20121002174624.GI4763@redhat.com> References: <1349197151-19645-1-git-send-email-will.deacon@arm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1349197151-19645-1-git-send-email-will.deacon@arm.com> Sender: owner-linux-mm@kvack.org To: Will Deacon Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, akpm@linux-foundation.org, mhocko@suse.cz, kirill@shutemov.name, Chris Metcalf , Steve Capper List-Id: linux-arch.vger.kernel.org On Tue, Oct 02, 2012 at 05:59:11PM +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. > > Cc: Andrea Arcangeli > Cc: Chris Metcalf > Signed-off-by: Steve Capper > Signed-off-by: Will Deacon > --- > > v2: - Use pmd_trans_huge_lock to guard against splitting pmds > - Propogate dirty (write) flag to low-level pmd modifier > > include/linux/huge_mm.h | 2 ++ > mm/huge_memory.c | 8 ++++++++ > mm/memory.c | 9 ++++++++- > 3 files changed, 18 insertions(+), 1 deletions(-) Reviewed-by: Andrea Arcangeli -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:31890 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755209Ab2JBRqk (ORCPT ); Tue, 2 Oct 2012 13:46:40 -0400 Date: Tue, 2 Oct 2012 19:46:24 +0200 From: Andrea Arcangeli Subject: Re: [PATCH v2] mm: thp: Set the accessed flag for old pages on access fault. Message-ID: <20121002174624.GI4763@redhat.com> References: <1349197151-19645-1-git-send-email-will.deacon@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1349197151-19645-1-git-send-email-will.deacon@arm.com> 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, akpm@linux-foundation.org, mhocko@suse.cz, kirill@shutemov.name, Chris Metcalf , Steve Capper Message-ID: <20121002174624.Fc-8cqYuOEiZi_PM9CANQ4RLA4fCyfLWwLb8Z6wev44@z> On Tue, Oct 02, 2012 at 05:59:11PM +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. > > Cc: Andrea Arcangeli > Cc: Chris Metcalf > Signed-off-by: Steve Capper > Signed-off-by: Will Deacon > --- > > v2: - Use pmd_trans_huge_lock to guard against splitting pmds > - Propogate dirty (write) flag to low-level pmd modifier > > include/linux/huge_mm.h | 2 ++ > mm/huge_memory.c | 8 ++++++++ > mm/memory.c | 9 ++++++++- > 3 files changed, 18 insertions(+), 1 deletions(-) Reviewed-by: Andrea Arcangeli