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=-11.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 3F8C6C4727D for ; Thu, 24 Sep 2020 13:44:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E9835238E3 for ; Thu, 24 Sep 2020 13:44:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727860AbgIXNoz (ORCPT ); Thu, 24 Sep 2020 09:44:55 -0400 Received: from mx2.suse.de ([195.135.220.15]:58550 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727859AbgIXNoz (ORCPT ); Thu, 24 Sep 2020 09:44:55 -0400 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 235E0ABAD; Thu, 24 Sep 2020 13:44:53 +0000 (UTC) Subject: Re: [PATCH RFC 4/4] mm/page_alloc: place pages to tail in __free_pages_core() To: David Hildenbrand , linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, linux-hyperv@vger.kernel.org, xen-devel@lists.xenproject.org, linux-acpi@vger.kernel.org, Andrew Morton , Alexander Duyck , Mel Gorman , Michal Hocko , Dave Hansen , Wei Yang , Oscar Salvador , Mike Rapoport , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu References: <20200916183411.64756-1-david@redhat.com> <20200916183411.64756-5-david@redhat.com> From: Vlastimil Babka Message-ID: <34a094bd-d37a-b735-14bb-ea65e2e2b7a1@suse.cz> Date: Thu, 24 Sep 2020 15:44:52 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20200916183411.64756-5-david@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org On 9/16/20 8:34 PM, David Hildenbrand wrote: > __free_pages_core() is used when exposing fresh memory to the buddy > during system boot and when onlining memory in generic_online_page(). > > generic_online_page() is used in two cases: > > 1. Direct memory onlining in online_pages(). > 2. Deferred memory onlining in memory-ballooning-like mechanisms (HyperV > balloon and virtio-mem), when parts of a section are kept > fake-offline to be fake-onlined later on. > > In 1, we already place pages to the tail of the freelist. Pages will be > freed to MIGRATE_ISOLATE lists first and moved to the tail of the freelists > via undo_isolate_page_range(). > > In 2, we currently don't implement a proper rule. In case of virtio-mem, > where we currently always online MAX_ORDER - 1 pages, the pages will be > placed to the HEAD of the freelist - undesireable. While the hyper-v > balloon calls generic_online_page() with single pages, usually it will > call it on successive single pages in a larger block. > > The pages are fresh, so place them to the tail of the freelists and avoid > the PCP. > > Note: If we detect that the new behavior is undesireable for > __free_pages_core() during boot, we can let the caller specify the > behavior. > > Cc: Andrew Morton > Cc: Alexander Duyck > Cc: Mel Gorman > Cc: Michal Hocko > Cc: Dave Hansen > Cc: Vlastimil Babka > Cc: Wei Yang > Cc: Oscar Salvador > Cc: Mike Rapoport > Cc: "K. Y. Srinivasan" > Cc: Haiyang Zhang > Cc: Stephen Hemminger > Cc: Wei Liu > Signed-off-by: David Hildenbrand Reviewed-by: Vlastimil Babka > --- > mm/page_alloc.c | 32 ++++++++++++++++++++------------ > 1 file changed, 20 insertions(+), 12 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 75b0f49b4022..50746e6dc21b 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -264,7 +264,8 @@ bool pm_suspended_storage(void) > unsigned int pageblock_order __read_mostly; > #endif > > -static void __free_pages_ok(struct page *page, unsigned int order); > +static void __free_pages_ok(struct page *page, unsigned int order, > + fop_t fop_flags); > > /* > * results with 256, 32 in the lowmem_reserve sysctl: > @@ -676,7 +677,7 @@ static void bad_page(struct page *page, const char *reason) > void free_compound_page(struct page *page) > { > mem_cgroup_uncharge(page); > - __free_pages_ok(page, compound_order(page)); > + __free_pages_ok(page, compound_order(page), FOP_NONE); > } > > void prep_compound_page(struct page *page, unsigned int order) > @@ -1402,17 +1403,15 @@ static void free_pcppages_bulk(struct zone *zone, int count, > spin_unlock(&zone->lock); > } > > -static void free_one_page(struct zone *zone, > - struct page *page, unsigned long pfn, > - unsigned int order, > - int migratetype) > +static void free_one_page(struct zone *zone, struct page *page, unsigned long pfn, > + unsigned int order, int migratetype, fop_t fop_flags) > { > spin_lock(&zone->lock); > if (unlikely(has_isolate_pageblock(zone) || > is_migrate_isolate(migratetype))) { > migratetype = get_pfnblock_migratetype(page, pfn); > } > - __free_one_page(page, pfn, zone, order, migratetype, FOP_NONE); > + __free_one_page(page, pfn, zone, order, migratetype, fop_flags); > spin_unlock(&zone->lock); > } > > @@ -1490,7 +1489,8 @@ void __meminit reserve_bootmem_region(phys_addr_t start, phys_addr_t end) > } > } > > -static void __free_pages_ok(struct page *page, unsigned int order) > +static void __free_pages_ok(struct page *page, unsigned int order, > + fop_t fop_flags) > { > unsigned long flags; > int migratetype; > @@ -1502,7 +1502,8 @@ static void __free_pages_ok(struct page *page, unsigned int order) > migratetype = get_pfnblock_migratetype(page, pfn); > local_irq_save(flags); > __count_vm_events(PGFREE, 1 << order); > - free_one_page(page_zone(page), page, pfn, order, migratetype); > + free_one_page(page_zone(page), page, pfn, order, migratetype, > + fop_flags); > local_irq_restore(flags); > } > > @@ -1523,7 +1524,13 @@ void __free_pages_core(struct page *page, unsigned int order) > > atomic_long_add(nr_pages, &page_zone(page)->managed_pages); > set_page_refcounted(page); > - __free_pages(page, order); > + > + /* > + * Bypass PCP and place fresh pages right to the tail, primarily > + * relevant for memory onlining. > + */ > + page_ref_dec(page); > + __free_pages_ok(page, order, FOP_TO_TAIL); > } > > #ifdef CONFIG_NEED_MULTIPLE_NODES > @@ -3167,7 +3174,8 @@ static void free_unref_page_commit(struct page *page, unsigned long pfn) > */ > if (migratetype >= MIGRATE_PCPTYPES) { > if (unlikely(is_migrate_isolate(migratetype))) { > - free_one_page(zone, page, pfn, 0, migratetype); > + free_one_page(zone, page, pfn, 0, migratetype, > + FOP_NONE); > return; > } > migratetype = MIGRATE_MOVABLE; > @@ -4984,7 +4992,7 @@ static inline void free_the_page(struct page *page, unsigned int order) > if (order == 0) /* Via pcp? */ > free_unref_page(page); > else > - __free_pages_ok(page, order); > + __free_pages_ok(page, order, FOP_NONE); > } > > void __free_pages(struct page *page, unsigned int order) >