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Fri, 09 Aug 2019 02:52:47 -0700 (PDT) Received: from bharath12345-Inspiron-5559 ([103.110.42.33]) by smtp.gmail.com with ESMTPSA id e24sm7992122pgk.21.2019.08.09.02.52.39 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 09 Aug 2019 02:52:47 -0700 (PDT) Date: Fri, 9 Aug 2019 15:22:36 +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: <20190809095236.GC22457@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) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. I ll send v5 once your convinced by my argument that ps is not necessary to set *pageshift and that *pageshift is being set. Thank you Bharath > > thanks, > -- > John Hubbard > NVIDIA