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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 25157C32789 for ; Tue, 6 Nov 2018 08:16:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id DACE220866 for ; Tue, 6 Nov 2018 08:16:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DACE220866 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729943AbeKFRk0 (ORCPT ); Tue, 6 Nov 2018 12:40:26 -0500 Received: from mx2.suse.de ([195.135.220.15]:57546 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728133AbeKFRkZ (ORCPT ); Tue, 6 Nov 2018 12:40:25 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay1.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id ED29DB102; Tue, 6 Nov 2018 08:16:21 +0000 (UTC) Subject: Re: [PATCH v2 2/2] mm/page_alloc: use a single function to free page To: Aaron Lu , linux-mm@kvack.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Cc: Andrew Morton , =?UTF-8?Q?Pawe=c5=82_Staszewski?= , Jesper Dangaard Brouer , Eric Dumazet , Tariq Toukan , Ilias Apalodimas , Yoel Caspersen , Mel Gorman , Saeed Mahameed , Michal Hocko , Dave Hansen , Alexander Duyck References: <20181105085820.6341-1-aaron.lu@intel.com> <20181105085820.6341-2-aaron.lu@intel.com> <20181106053037.GD6203@intel.com> From: Vlastimil Babka Openpgp: preference=signencrypt Autocrypt: addr=vbabka@suse.cz; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <20181106053037.GD6203@intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/6/18 6:30 AM, Aaron Lu wrote: > We have multiple places of freeing a page, most of them doing similar > things and a common function can be used to reduce code duplicate. > > It also avoids bug fixed in one function but left in another. > > Signed-off-by: Aaron Lu Acked-by: Vlastimil Babka I assume there's no arch that would run page_ref_sub_and_test(1) slower than put_page_testzero(), for the critical __free_pages() case? > --- > v2: move comments close to code as suggested by Dave. > > mm/page_alloc.c | 36 ++++++++++++++++-------------------- > 1 file changed, 16 insertions(+), 20 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 91a9a6af41a2..4faf6b7bf225 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -4425,9 +4425,17 @@ unsigned long get_zeroed_page(gfp_t gfp_mask) > } > EXPORT_SYMBOL(get_zeroed_page); > > -void __free_pages(struct page *page, unsigned int order) > +static inline void free_the_page(struct page *page, unsigned int order, int nr) > { > - if (put_page_testzero(page)) { > + VM_BUG_ON_PAGE(page_ref_count(page) == 0, page); > + > + /* > + * Free a page by reducing its ref count by @nr. > + * If its refcount reaches 0, then according to its order: > + * order0: send to PCP; > + * high order: directly send to Buddy. > + */ > + if (page_ref_sub_and_test(page, nr)) { > if (order == 0) > free_unref_page(page); > else > @@ -4435,6 +4443,10 @@ void __free_pages(struct page *page, unsigned int order) > } > } > > +void __free_pages(struct page *page, unsigned int order) > +{ > + free_the_page(page, order, 1); > +} > EXPORT_SYMBOL(__free_pages); > > void free_pages(unsigned long addr, unsigned int order) > @@ -4481,16 +4493,7 @@ static struct page *__page_frag_cache_refill(struct page_frag_cache *nc, > > void __page_frag_cache_drain(struct page *page, unsigned int count) > { > - VM_BUG_ON_PAGE(page_ref_count(page) == 0, page); > - > - if (page_ref_sub_and_test(page, count)) { > - unsigned int order = compound_order(page); > - > - if (order == 0) > - free_unref_page(page); > - else > - __free_pages_ok(page, order); > - } > + free_the_page(page, compound_order(page), count); > } > EXPORT_SYMBOL(__page_frag_cache_drain); > > @@ -4555,14 +4558,7 @@ void page_frag_free(void *addr) > { > struct page *page = virt_to_head_page(addr); > > - if (unlikely(put_page_testzero(page))) { > - unsigned int order = compound_order(page); > - > - if (order == 0) > - free_unref_page(page); > - else > - __free_pages_ok(page, order); > - } > + free_the_page(page, compound_order(page), 1); > } > EXPORT_SYMBOL(page_frag_free); > >