From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it0-f70.google.com (mail-it0-f70.google.com [209.85.214.70]) by kanga.kvack.org (Postfix) with ESMTP id 1CFF46B0417 for ; Wed, 21 Jun 2017 11:49:26 -0400 (EDT) Received: by mail-it0-f70.google.com with SMTP id u127so6533993itg.11 for ; Wed, 21 Jun 2017 08:49:26 -0700 (PDT) Received: from smtprelay.synopsys.com (us01smtprelay-2.synopsys.com. [198.182.47.9]) by mx.google.com with ESMTPS id m93si2212736ioi.35.2017.06.21.08.49.24 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 21 Jun 2017 08:49:25 -0700 (PDT) Subject: Re: [PATCHv2 1/3] x86/mm: Provide pmdp_establish() helper References: <20170615145224.66200-1-kirill.shutemov@linux.intel.com> <20170615145224.66200-2-kirill.shutemov@linux.intel.com> <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> From: Vineet Gupta Message-ID: <1af1738a-88a7-987c-eca7-2118d66514e1@synopsys.com> Date: Wed, 21 Jun 2017 08:49:03 -0700 MIME-Version: 1.0 In-Reply-To: <20170621112702.GC10220@e104818-lin.cambridge.arm.com> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: owner-linux-mm@kvack.org List-ID: To: Catalin Marinas , "Kirill A. Shutemov" Cc: "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 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 ? -Vineet -- 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