From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 768A1C31E40 for ; Fri, 9 Aug 2019 18:04:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4D2342166E for ; Fri, 9 Aug 2019 18:04:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="Lm48/h4n" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2437303AbfHISEs (ORCPT ); Fri, 9 Aug 2019 14:04:48 -0400 Received: from hqemgate16.nvidia.com ([216.228.121.65]:13666 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726463AbfHISEr (ORCPT ); Fri, 9 Aug 2019 14:04:47 -0400 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Fri, 09 Aug 2019 11:04:48 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Fri, 09 Aug 2019 11:04:47 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Fri, 09 Aug 2019 11:04:47 -0700 Received: from [10.2.165.207] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Fri, 9 Aug 2019 18:04:46 +0000 Subject: Re: [Linux-kernel-mentees][PATCH v4 1/1] sgi-gru: Remove *pte_lookup functions To: Bharath Vedartham CC: , , , , , , , , , References: <1565290555-14126-1-git-send-email-linux.bhar@gmail.com> <1565290555-14126-2-git-send-email-linux.bhar@gmail.com> <20190809094406.GA22457@bharath12345-Inspiron-5559> From: John Hubbard X-Nvconfidentiality: public Message-ID: Date: Fri, 9 Aug 2019 11:03:14 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190809094406.GA22457@bharath12345-Inspiron-5559> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL101.nvidia.com (172.20.187.10) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1565373888; bh=g0FmRWOVSQw+ovYa/Gu5Q2BPMATNeZLwtOFaVN9ZPw0=; h=X-PGP-Universal:Subject:To:CC:References:From:X-Nvconfidentiality: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=Lm48/h4n/E5d/oO1iuhNqiTdYfI3bWD99pXlSulIAVr+7+NFRBRx04unypjYa1LXI Qu4NX+U659GBezGwaMcDXMJU0olVDQx+bBlgV+unRtfatA4yS2dWJxVAXe/iowCU4x 0GAz9g4BgSU+xFpBfQVrsgoJPYC5iS30AC3Opk/9+2XoJDfHTPY12Ub/9+JxFl6irE KcsFlVYTcES6cGUQKT3HWrC/e0R6pQqwaF3SLlUyeXHHoS6q3AkNvxCzBgk8SbSyTj pO7Z0ED/1Dy0mBD1w54rbULkdwFKXtgUu6IGkQ7U0H1qrJd68vPLFJvdGloq1H30oh sfUnjNFy9oqKA== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/9/19 2:44 AM, Bharath Vedartham wrote: > On Thu, Aug 08, 2019 at 04:21:44PM -0700, John Hubbard wrote: >> On 8/8/19 11:55 AM, Bharath Vedartham wrote: >> ... >>> static int gru_vtop(struct gru_thread_state *gts, unsigned long vaddr, >>> int write, int atomic, unsigned long *gpa, int *pageshift) >>> { >>> struct mm_struct *mm = gts->ts_mm; >>> struct vm_area_struct *vma; >>> unsigned long paddr; >>> - int ret, ps; >>> + int ret; >>> + struct page *page; >>> >>> vma = find_vma(mm, vaddr); >>> if (!vma) >>> @@ -263,21 +187,33 @@ static int gru_vtop(struct gru_thread_state *gts, unsigned long vaddr, >>> >>> /* >>> * Atomic lookup is faster & usually works even if called in non-atomic >>> - * context. >>> + * context. get_user_pages_fast does atomic lookup before falling back to >>> + * slow gup. >>> */ >>> rmb(); /* Must/check ms_range_active before loading PTEs */ >>> - ret = atomic_pte_lookup(vma, vaddr, write, &paddr, &ps); >>> - if (ret) { >>> - if (atomic) >>> + if (atomic) { >>> + ret = __get_user_pages_fast(vaddr, 1, write, &page); >>> + if (!ret) >>> goto upm; >>> - if (non_atomic_pte_lookup(vma, vaddr, write, &paddr, &ps)) >>> + } else { >>> + ret = get_user_pages_fast(vaddr, 1, write ? FOLL_WRITE : 0, &page); >>> + if (!ret) >>> goto inval; >>> } >>> + >>> + paddr = page_to_phys(page); >>> + put_user_page(page); >>> + >>> + if (unlikely(is_vm_hugetlb_page(vma))) >>> + *pageshift = HPAGE_SHIFT; >>> + else >>> + *pageshift = PAGE_SHIFT; >>> + >>> if (is_gru_paddr(paddr)) >>> goto inval; >>> - paddr = paddr & ~((1UL << ps) - 1); >>> + paddr = paddr & ~((1UL << *pageshift) - 1); >>> *gpa = uv_soc_phys_ram_to_gpa(paddr); >>> - *pageshift = ps; >> >> Why are you no longer setting *pageshift? There are a couple of callers >> that both use this variable. > Hi John, > > I did set *pageshift. The if statement above sets *pageshift. ps was > used to retrive the pageshift value when the pte_lookup functions were > present. ps was passed by reference to those functions and set by them. > But here since we are trying to remove those functions, we don't need ps > and we directly set *pageshift to HPAGE_SHIFT or PAGE_SHIFT based on the > type of vma. > > Hope this clears things up? > Right you are, sorry for overlooking that. Looks good. thanks, -- John Hubbard NVIDIA