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[209.85.220.65]) by mx.google.com with SMTPS id g18sor78098774pfo.60.2019.08.09.02.44.17 for (Google Transport Security); Fri, 09 Aug 2019 02:44:17 -0700 (PDT) Received-SPF: pass (google.com: domain of linux.bhar@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=Uj3D0+T2; spf=pass (google.com: domain of linux.bhar@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=linux.bhar@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=0MjjxEATeDSohSUdPgCn+0npRclOTNWQmeqagttLXsE=; b=Uj3D0+T2IeTt2j8R9IQoWagucl2E8dAmOFplTadmEtycTdbXiM6UlavYMVIWRj02Cw 4nSjNZnzwBdIAEkY38minKr8sYfOUzw8/WLlP8ed8SLzlIhwkZoWRaa1hLLX0HTNpU3l +C0O3IoWFhNMlGSkYFNWh5qqg1YWt7jHjjNwXnsLsenEtvNuAmN6uAW6tETi5HZkGIZL DrOB+8THq13ltaU/8cqB9++tw1zvfEiBQBoX3Cw1iovi0VSPgY9Yvc4UinD0eWP8t6hd ZwvocRvxWFkXtMq3PNSgz9fy8Uktwgue1HOdo+jRr7RaMf3sRku+Hwvkpoi4PR5Myd9g ufQw== X-Google-Smtp-Source: APXvYqwKbvHj8qkjrkEYqfdwuA24Q1Iov787Zkesjq5b/OE+ycYpMk/fRKyoJ/9LftbwlyAmci+LfQ== X-Received: by 2002:aa7:9254:: with SMTP id 20mr21121887pfp.212.1565343856824; Fri, 09 Aug 2019 02:44:16 -0700 (PDT) Received: from bharath12345-Inspiron-5559 ([103.110.42.33]) by smtp.gmail.com with ESMTPSA id e9sm2925944pfh.155.2019.08.09.02.44.10 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 09 Aug 2019 02:44:16 -0700 (PDT) Date: Fri, 9 Aug 2019 15:14:06 +0530 From: Bharath Vedartham To: John Hubbard Cc: arnd@arndb.de, gregkh@linuxfoundation.org, sivanich@sgi.com, ira.weiny@intel.com, jglisse@redhat.com, william.kucharski@oracle.com, hch@lst.de, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-kernel-mentees@lists.linuxfoundation.org Subject: Re: [Linux-kernel-mentees][PATCH v4 1/1] sgi-gru: Remove *pte_lookup functions Message-ID: <20190809094406.GA22457@bharath12345-Inspiron-5559> References: <1565290555-14126-1-git-send-email-linux.bhar@gmail.com> <1565290555-14126-2-git-send-email-linux.bhar@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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? Thank you Bharath > > thanks, > -- > John Hubbard > NVIDIA