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=-11.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,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 1C5EAC47425 for ; Fri, 2 Oct 2020 13:41:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 76B9320719 for ; Fri, 2 Oct 2020 13:41:19 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="odvEcVR3" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 76B9320719 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C32336B0062; Fri, 2 Oct 2020 09:41:18 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id BBCED6B006C; Fri, 2 Oct 2020 09:41:18 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A83636B006E; Fri, 2 Oct 2020 09:41:18 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0168.hostedemail.com [216.40.44.168]) by kanga.kvack.org (Postfix) with ESMTP id 73F896B0062 for ; Fri, 2 Oct 2020 09:41:18 -0400 (EDT) Received: from smtpin22.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id ED3D0180AD806 for ; Fri, 2 Oct 2020 13:41:17 +0000 (UTC) X-FDA: 77327096994.22.point89_3113a5f271a4 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin22.hostedemail.com (Postfix) with ESMTP id C710418038E60 for ; Fri, 2 Oct 2020 13:41:17 +0000 (UTC) X-HE-Tag: point89_3113a5f271a4 X-Filterd-Recvd-Size: 9093 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Fri, 2 Oct 2020 13:41:17 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1601646076; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=Z3ByYrh+VAhRxeH0eK8Na0KVOwY/vMeBd7zzpOzuyh8=; b=odvEcVR3MGe4ScG+CTx7+dM1KQK8SJGRd5CwKYZrKZOXio34wK3PH2wl9CUz9kMHYeYQk3 BZPLzK9nIIqiothIjrit3Slk86uffisO5vN5J/leVvbHUXfwbIMT2Ft1ZKqM3IeJkWjqwQ TOwk2hwVtjDVFO77HnCPzt1saLmpGVM= Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id F40DAAD12; Fri, 2 Oct 2020 13:41:15 +0000 (UTC) Date: Fri, 2 Oct 2020 15:41:15 +0200 From: Michal Hocko To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-hyperv@vger.kernel.org, xen-devel@lists.xenproject.org, linux-acpi@vger.kernel.org, Andrew Morton , Vlastimil Babka , Oscar Salvador , Alexander Duyck , Mel Gorman , Dave Hansen , Wei Yang , Mike Rapoport , "K. Y. Srinivasan" , Haiyang Zhang , Stephen Hemminger , Wei Liu Subject: Re: [PATCH v1 4/5] mm/page_alloc: place pages to tail in __free_pages_core() Message-ID: <20201002134115.GJ4555@dhcp22.suse.cz> References: <20200928182110.7050-1-david@redhat.com> <20200928182110.7050-5-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200928182110.7050-5-david@redhat.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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 Mon 28-09-20 20:21:09, 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. In __free_pages_core(), remove the now superflouos call to > set_page_refcounted() and add a comment regarding page initialization and > the refcount. > > Note: In 2. we currently don't shuffle. If ever relevant (page shuffling > is usually of limited use in virtualized environments), we might want to > shuffle after a sequence of generic_online_page() calls in the > relevant callers. It took some time to get through all the freeing paths with subtle differences but this looks reasonable. You are mentioning that this influences a boot time free memory ordering as well but only very briefly. I do not expect this to make a huge difference but who knows. It makes some sense to add pages in the order they show up in the physical address ordering. > Reviewed-by: Vlastimil Babka > Reviewed-by: Oscar Salvador > 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 That being said I do not see any fundamental problems. Acked-by: Michal Hocko > --- > mm/page_alloc.c | 37 ++++++++++++++++++++++++------------- > 1 file changed, 24 insertions(+), 13 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index d5a5f528b8ca..8a2134fe9947 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -270,7 +270,8 @@ 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: > @@ -682,7 +683,7 @@ 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) > @@ -1419,17 +1420,15 @@ 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); > } > > @@ -1507,7 +1506,8 @@ 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; > @@ -1519,7 +1519,8 @@ 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); > } > > @@ -1529,6 +1530,11 @@ void __free_pages_core(struct page *page, unsigned int order) > struct page *p = page; > unsigned int loop; > > + /* > + * When initializing the memmap, init_single_page() sets the refcount > + * of all pages to 1 ("allocated"/"not free"). We have to set the > + * refcount of all involved pages to 0. > + */ > prefetchw(p); > for (loop = 0; loop < (nr_pages - 1); loop++, p++) { > prefetchw(p + 1); > @@ -1539,8 +1545,12 @@ void __free_pages_core(struct page *page, unsigned int order) > set_page_count(p, 0); > > 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. > + */ > + __free_pages_ok(page, order, FOP_TO_TAIL); > } > > #ifdef CONFIG_NEED_MULTIPLE_NODES > @@ -3171,7 +3181,8 @@ 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; > @@ -5063,7 +5074,7 @@ 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) > -- > 2.26.2 > -- Michal Hocko SUSE Labs