From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753258AbdFURVU (ORCPT ); Wed, 21 Jun 2017 13:21:20 -0400 Received: from us01smtprelay-2.synopsys.com ([198.182.47.9]:33054 "EHLO smtprelay.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753034AbdFURVS (ORCPT ); Wed, 21 Jun 2017 13:21:18 -0400 Subject: Re: [PATCHv2 1/3] x86/mm: Provide pmdp_establish() helper To: "Kirill A. Shutemov" 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 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> <1af1738a-88a7-987c-eca7-2118d66514e1@synopsys.com> <20170621171558.7zrgzc7uk3kspcys@node.shutemov.name> From: Vineet Gupta Message-ID: Date: Wed, 21 Jun 2017 10:20:47 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <20170621171558.7zrgzc7uk3kspcys@node.shutemov.name> Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US X-Originating-IP: [10.12.196.146] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 don't want it to be used by default without attention from architecture > maintainer. It can lead unnoticied breakage if THP got enabled on new > arch. Makes sense ! -Vineet From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vineet Gupta Subject: Re: [PATCHv2 1/3] x86/mm: Provide pmdp_establish() helper Date: Wed, 21 Jun 2017 10:20:47 -0700 Message-ID: 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> <1af1738a-88a7-987c-eca7-2118d66514e1@synopsys.com> <20170621171558.7zrgzc7uk3kspcys@node.shutemov.name> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170621171558.7zrgzc7uk3kspcys@node.shutemov.name> Content-Language: en-US Sender: owner-linux-mm@kvack.org To: "Kirill A. Shutemov" 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 List-Id: linux-arch.vger.kernel.org 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 don't want it to be used by default without attention from architecture > maintainer. It can lead unnoticied breakage if THP got enabled on new > arch. Makes sense ! -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