Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751938AbdFURwJ (ORCPT ); Wed, 21 Jun 2017 13:52:09 -0400 Received: from mail-wr0-f193.google.com ([209.85.128.193]:35132 "EHLO mail-wr0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751140AbdFURwG (ORCPT ); Wed, 21 Jun 2017 13:52:06 -0400 Date: Wed, 21 Jun 2017 20:52:03 +0300 From: "Kirill A. Shutemov" To: Vineet Gupta Cc: Catalin Marinas , "Kirill A. Shutemov" , Andrew Morton , Vlastimil Babka , Russell King , Will Deacon , Ralf Baechle , "David S. Miller" , "Aneesh Kumar K . V" , Martin Schwidefsky , Heiko Carstens , Andrea Arcangeli , "linux-arch@vger.kernel.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Ingo Molnar , "H . Peter Anvin" , Thomas Gleixner Subject: Re: [PATCHv2 1/3] x86/mm: Provide pmdp_establish() helper Message-ID: <20170621175203.g2susfjihyqrf245@node.shutemov.name> References: <20170619152228.GE3024@e104818-lin.cambridge.arm.com> <20170619160005.wgj4nymtj2nntfll@node.shutemov.name> <20170619170911.GF3024@e104818-lin.cambridge.arm.com> <20170619215210.2crwjou3sfdcj73d@node.shutemov.name> <20170620155438.GC21383@e104818-lin.cambridge.arm.com> <20170621095303.q5fqt5a3ao5smko6@node.shutemov.name> <20170621112702.GC10220@e104818-lin.cambridge.arm.com> <1af1738a-88a7-987c-eca7-2118d66514e1@synopsys.com> <20170621171558.7zrgzc7uk3kspcys@node.shutemov.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170609 (1.8.3) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1923 Lines: 41 On Wed, Jun 21, 2017 at 10:20:47AM -0700, Vineet Gupta wrote: > On 06/21/2017 10:16 AM, Kirill A. Shutemov wrote: > > On Wed, Jun 21, 2017 at 08:49:03AM -0700, Vineet Gupta wrote: > > > On 06/21/2017 04:27 AM, Catalin Marinas wrote: > > > > On Wed, Jun 21, 2017 at 12:53:03PM +0300, Kirill A. Shutemov wrote: > > > > > > > > > > On Thu, Jun 15, 2017 at 05:52:22PM +0300, Kirill A. Shutemov wrote: > > > > > > > > > > > We need an atomic way to setup pmd page table entry, avoiding races with > > > > > > > > > > > CPU setting dirty/accessed bits. This is required to implement > > > > > > > > > > > pmdp_invalidate() that doesn't loose these bits. > > > > [...] > > > > > Any chance you could help me with arm too? > > > > On arm (ARMv7 with LPAE) we don't have hardware updates of the > > > > access/dirty bits, so a generic implementation would suffice. I didn't > > > > find one in your patches, so here's an untested version: > > > > > > > > static inline pmd_t pmdp_establish(struct mm_struct *mm, unsigned long address, > > > > pmd_t *pmdp, pmd_t pmd) > > > > { > > > > pmd_t old_pmd = *pmdp; > > > > set_pmd_at(mm, address, pmdp, pmd); > > > > return old_pmd; > > > > } > > > So it seems the discussions have settled down and pmdp_establish() can be > > > implemented in generic way as above and it will suffice if arch doesn't have > > > a special need. It would be nice to add the comment above generic version > > > that it only needs to be implemented if hardware sets the accessed/dirty > > > bits ! > > > > > > Then nothing special is needed for ARC - right ? > > I will define generic version as Catalin proposed with a comment, but > > under the name generic_pmdp_establish. An arch can make use of it by > > > > #define pmdp_establish generic_pmdp_establish > > Can you do that for ARC in your next posting - or want me to once you have > posted that ? I'll do this. -- Kirill A. Shutemov