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[91.12.103.116]) by smtp.gmail.com with ESMTPSA id i24sm5497209wml.26.2021.10.13.09.33.07 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Oct 2021 09:33:07 -0700 (PDT) Message-ID: Date: Wed, 13 Oct 2021 18:33:06 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Content-Language: en-US To: Kent Overstreet , linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, linux-raid@vger.kernel.org, linux-block@vger.kernel.org, axboe@kernel.dk Cc: alexander.h.duyck@linux.intel.com References: <20211013160034.3472923-1-kent.overstreet@gmail.com> <20211013160034.3472923-2-kent.overstreet@gmail.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH 1/5] mm: Make free_area->nr_free per migratetype In-Reply-To: <20211013160034.3472923-2-kent.overstreet@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mostly LGTM. I recall that in some corner cases the migratetype stored for a pcppage does not correspond to the pagetype of the pfnblock ... I do wonder if that can trick us here in doing some accounting wrong., no that we account free pages per mirgatetype. > /* > * Set the pageblock if the isolated page is at least half of a > @@ -6038,14 +6038,16 @@ void show_free_areas(unsigned int filter, nodemask_t *nodemask) > struct free_area *area = &zone->free_area[order]; > int type; > > - nr[order] = area->nr_free; > - total += nr[order] << order; > + nr[order] = 0; > + types[order] = 0; Why the indentation change? Looks unrelated to me. > > - types[order] = 0; > for (type = 0; type < MIGRATE_TYPES; type++) { > if (!free_area_empty(area, type)) > types[order] |= 1 << type; > + nr[order] += area->nr_free[type]; > } > + > + total += nr[order] << order; > } > spin_unlock_irqrestore(&zone->lock, flags); > for (order = 0; order < MAX_ORDER; order++) { > @@ -6623,7 +6625,7 @@ static void __meminit zone_init_free_lists(struct zone *zone) > unsigned int order, t; > for_each_migratetype_order(order, t) { > INIT_LIST_HEAD(&zone->free_area[order].free_list[t]); > - zone->free_area[order].nr_free = 0; > + zone->free_area[order].nr_free[t] = 0; > } > } > > @@ -9317,6 +9319,7 @@ void __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) > struct page *page; > struct zone *zone; > unsigned int order; > + unsigned int migratetype; > unsigned long flags; > > offline_mem_sections(pfn, end_pfn); > @@ -9346,7 +9349,8 @@ void __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn) > BUG_ON(page_count(page)); > BUG_ON(!PageBuddy(page)); > order = buddy_order(page); > - del_page_from_free_list(page, zone, order); > + migratetype = get_pfnblock_migratetype(page, pfn); As the free pages are isolated, theoretically this should be MIGRATE_ISOLATE. > + del_page_from_free_list(page, zone, order, migratetype); > pfn += (1 << order); > } > spin_unlock_irqrestore(&zone->lock, flags); > @@ -9428,7 +9432,7 @@ bool take_page_off_buddy(struct page *page) > int migratetype = get_pfnblock_migratetype(page_head, > pfn_head); > > - del_page_from_free_list(page_head, zone, page_order); > + del_page_from_free_list(page_head, zone, page_order, migratetype); > break_down_buddy_pages(zone, page_head, page, 0, > page_order, migratetype); > if (!is_migrate_isolate(migratetype)) > diff --git a/mm/page_reporting.c b/mm/page_reporting.c > index 382958eef8..4e45ae95db 100644 > --- a/mm/page_reporting.c > +++ b/mm/page_reporting.c > @@ -145,7 +145,7 @@ page_reporting_cycle(struct page_reporting_dev_info *prdev, struct zone *zone, > * The division here should be cheap since PAGE_REPORTING_CAPACITY > * should always be a power of 2. > */ > - budget = DIV_ROUND_UP(area->nr_free, PAGE_REPORTING_CAPACITY * 16); > + budget = DIV_ROUND_UP(area->nr_free[mt], PAGE_REPORTING_CAPACITY * 16); > I think we might want the total free pages here. If we want to change the behavior, we should do it in a separate patch. -- Thanks, David / dhildenb