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=-5.3 required=3.0 tests=BAYES_00, 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 1ED77C388F7 for ; Mon, 9 Nov 2020 17:21:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D3E642083B for ; Mon, 9 Nov 2020 17:21:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731465AbgKIRVt (ORCPT ); Mon, 9 Nov 2020 12:21:49 -0500 Received: from mx2.suse.de ([195.135.220.15]:52812 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730706AbgKIRVt (ORCPT ); Mon, 9 Nov 2020 12:21:49 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id DEEADAD07; Mon, 9 Nov 2020 17:21:47 +0000 (UTC) Date: Mon, 9 Nov 2020 18:21:44 +0100 From: Oscar Salvador To: Muchun Song Cc: corbet@lwn.net, mike.kravetz@oracle.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, viro@zeniv.linux.org.uk, akpm@linux-foundation.org, paulmck@kernel.org, mchehab+huawei@kernel.org, pawan.kumar.gupta@linux.intel.com, rdunlap@infradead.org, oneukum@suse.com, anshuman.khandual@arm.com, jroedel@suse.de, almasrymina@google.com, rientjes@google.com, willy@infradead.org, mhocko@suse.com, duanxiongchun@bytedance.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v3 05/21] mm/hugetlb: Introduce pgtable allocation/freeing helpers Message-ID: <20201109172144.GB17356@linux> References: <20201108141113.65450-1-songmuchun@bytedance.com> <20201108141113.65450-6-songmuchun@bytedance.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201108141113.65450-6-songmuchun@bytedance.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Sun, Nov 08, 2020 at 10:10:57PM +0800, Muchun Song wrote: > +static inline unsigned int pgtable_pages_to_prealloc_per_hpage(struct hstate *h) > +{ > + unsigned long vmemmap_size = vmemmap_pages_size_per_hpage(h); > + > + /* > + * No need pre-allocate page tabels when there is no vmemmap pages > + * to free. s /tabels/tables/ > +static int vmemmap_pgtable_prealloc(struct hstate *h, struct page *page) > +{ > + int i; > + pgtable_t pgtable; > + unsigned int nr = pgtable_pages_to_prealloc_per_hpage(h); > + > + if (!nr) > + return 0; > + > + vmemmap_pgtable_init(page); > + > + for (i = 0; i < nr; i++) { > + pte_t *pte_p; > + > + pte_p = pte_alloc_one_kernel(&init_mm); > + if (!pte_p) > + goto out; > + vmemmap_pgtable_deposit(page, virt_to_page(pte_p)); > + } > + > + return 0; > +out: > + while (i-- && (pgtable = vmemmap_pgtable_withdraw(page))) > + pte_free_kernel(&init_mm, page_to_virt(pgtable)); would not be enough to: while (pgtable = vmemmap_pgtable_withdrag(page)) pte_free_kernel(&init_mm, page_to_virt(pgtable)); > + return -ENOMEM; > +} > + > +static void vmemmap_pgtable_free(struct hstate *h, struct page *page) > +{ > + pgtable_t pgtable; > + unsigned int nr = pgtable_pages_to_prealloc_per_hpage(h); > + > + if (!nr) > + return; We can get rid of "nr" and its check and keep only the check below, right? AFAICS, they go together, e.g: if page_huge_pte does not return null, it means that we preallocated a pagetable, and viceversa. > + > + pgtable = page_huge_pte(page); > + if (!pgtable) > + return; > + > + while (nr-- && (pgtable = vmemmap_pgtable_withdraw(page))) > + pte_free_kernel(&init_mm, page_to_virt(pgtable)); Same as above, that "nr" can go? -- Oscar Salvador SUSE L3