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=-5.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 980F1C7618F for ; Mon, 22 Jul 2019 23:06:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 64F1021955 for ; Mon, 22 Jul 2019 23:06:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="ic76KIn3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733057AbfGVXGM (ORCPT ); Mon, 22 Jul 2019 19:06:12 -0400 Received: from hqemgate16.nvidia.com ([216.228.121.65]:15593 "EHLO hqemgate16.nvidia.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728191AbfGVXGM (ORCPT ); Mon, 22 Jul 2019 19:06:12 -0400 Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate16.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 22 Jul 2019 16:06:08 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Mon, 22 Jul 2019 16:06:11 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Mon, 22 Jul 2019 16:06:11 -0700 Received: from [10.110.48.28] (10.124.1.5) by HQMAIL107.nvidia.com (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 22 Jul 2019 23:06:10 +0000 Subject: Re: [PATCH 3/3] sgi-gru: Use __get_user_pages_fast in atomic_pte_lookup To: Bharath Vedartham CC: , , , , , , References: <1563724685-6540-1-git-send-email-linux.bhar@gmail.com> <1563724685-6540-4-git-send-email-linux.bhar@gmail.com> <20190722175310.GC12278@bharath12345-Inspiron-5559> From: John Hubbard X-Nvconfidentiality: public Message-ID: <15223dd3-8018-65f0-dc0b-aef43945e54e@nvidia.com> Date: Mon, 22 Jul 2019 16:06:09 -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: <20190722175310.GC12278@bharath12345-Inspiron-5559> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL105.nvidia.com (172.20.187.12) To HQMAIL107.nvidia.com (172.20.187.13) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1563836768; bh=8L2t5eNHtNZSBlKOQ4UF/BYJB/qKm9Cii8LsBa8jE4c=; 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=ic76KIn3tVio6vzVxE2FnWPCYuR7SXKbShoLnDet+7TPVb2NHLdtlV/kDMJCRRg5I t95iAmFuphbDWTfhJWQVcutfK4K3SSC7t0F07t/GUpbG5ve7mqdnCpz9zM5WVTZl+o HGCA5yP0OGGXa76TuqLlfEc+S1OholGwzkmaROv5W2B7rQgMJbNC/NEkcDdp4TjjyS 4k83+HfBmE41XSDRriG7l+FvX8LSKEaI56L7iHXvhZ1cFPSFVCko1yx/ukVBFs4KaH LwwauagCcI6DjUxHcUesRH9e43/t9Wl7Iz+snHAqXnxusLedgIJXzOB3cZRf98KVyL 7I7k+ccEnSXyQ== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/22/19 10:53 AM, Bharath Vedartham wrote: > On Sun, Jul 21, 2019 at 07:32:36PM -0700, John Hubbard wrote: >> On 7/21/19 8:58 AM, Bharath Vedartham wrote: ... >> Also, optional: as long as you're there, atomic_pte_lookup() ought to >> either return a bool (true == success) or an errno, rather than a >> numeric zero or one. > That makes sense. But the code which uses atomic_pte_lookup uses the > return value of 1 for success and failure value of 0 in gru_vtop. That's > why I did not mess with the return values in this code. It would require > some change in the driver functionality which I am not ready to do :( It's a static function with only one caller. You could just merge in something like this, on top of what you have: diff --git a/drivers/misc/sgi-gru/grufault.c b/drivers/misc/sgi-gru/grufault.c index 121c9a4ccb94..2f768fc06432 100644 --- a/drivers/misc/sgi-gru/grufault.c +++ b/drivers/misc/sgi-gru/grufault.c @@ -189,10 +189,11 @@ static int non_atomic_pte_lookup(struct vm_area_struct *vma, return 0; } -/* - * atomic_pte_lookup +/** + * atomic_pte_lookup() - Convert a user virtual address to a physical address + * @Return: true for success, false for failure. Failure means that the page + * could not be pinned via gup fast. * - * Convert a user virtual address to a physical address * Only supports Intel large pages (2MB only) on x86_64. * ZZZ - hugepage support is incomplete * @@ -207,12 +208,12 @@ static int atomic_pte_lookup(struct vm_area_struct *vma, unsigned long vaddr, *pageshift = is_vm_hugetlb_page(vma) ? HPAGE_SHIFT : PAGE_SHIFT; if (!__get_user_pages_fast(vaddr, 1, write, &page)) - return 1; + return false; *paddr = page_to_phys(page); put_user_page(page); - return 0; + return true; } static int gru_vtop(struct gru_thread_state *gts, unsigned long vaddr, @@ -221,7 +222,8 @@ static int gru_vtop(struct gru_thread_state *gts, unsigned long vaddr, struct mm_struct *mm = gts->ts_mm; struct vm_area_struct *vma; unsigned long paddr; - int ret, ps; + int ps; + bool success; vma = find_vma(mm, vaddr); if (!vma) @@ -232,8 +234,8 @@ static int gru_vtop(struct gru_thread_state *gts, unsigned long vaddr, * context. */ rmb(); /* Must/check ms_range_active before loading PTEs */ - ret = atomic_pte_lookup(vma, vaddr, write, &paddr, &ps); - if (ret) { + success = atomic_pte_lookup(vma, vaddr, write, &paddr, &ps); + if (!success) { if (atomic) goto upm; if (non_atomic_pte_lookup(vma, vaddr, write, &paddr, &ps)) thanks, -- John Hubbard NVIDIA