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Date: Fri, 11 Mar 2016 18:07:40 +0100 From: Vlastimil Babka <vbabka@...e.cz> To: Joonsoo Kim <js1304@...il.com>, "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com> Cc: Laura Abbott <labbott@...hat.com>, Joonsoo Kim <iamjoonsoo.kim@....com>, Hanjun Guo <guohanjun@...wei.com>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, Andrew Morton <akpm@...ux-foundation.org>, Sasha Levin <sasha.levin@...cle.com>, Laura Abbott <lauraa@...eaurora.org>, qiuxishi <qiuxishi@...wei.com>, Catalin Marinas <Catalin.Marinas@....com>, Will Deacon <will.deacon@....com>, Arnd Bergmann <arnd@...db.de>, dingtinahong <dingtianhong@...wei.com>, chenjie6@...wei.com, "linux-mm@...ck.org" <linux-mm@...ck.org> Subject: Re: Suspicious error for CMA stress test On 03/11/2016 04:00 PM, Joonsoo Kim wrote: > 2016-03-09 10:23 GMT+09:00 Leizhen (ThunderTown) <thunder.leizhen@...wei.com>: >> >> Hi, Joonsoo: >> This new patch worked well. Do you plan to upstream it in the near furture? > > Of course! > But, I should think more because it touches allocator's fastpatch and > I'd like to detour. > If I fail to think a better solution, I will send it as is, soon. How about something like this? Just and idea, probably buggy (off-by-one etc.). Should keep away cost from <pageblock_order iterations at the expense of the relatively fewer >pageblock_order iterations. diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ff1e3cbc8956..b8005a07b2a1 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -685,21 +685,13 @@ static inline void __free_one_page(struct page *page, unsigned long combined_idx; unsigned long uninitialized_var(buddy_idx); struct page *buddy; - unsigned int max_order = MAX_ORDER; + unsigned int max_order = pageblock_order + 1; VM_BUG_ON(!zone_is_initialized(zone)); VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page); VM_BUG_ON(migratetype == -1); - if (is_migrate_isolate(migratetype)) { - /* - * We restrict max order of merging to prevent merge - * between freepages on isolate pageblock and normal - * pageblock. Without this, pageblock isolation - * could cause incorrect freepage accounting. - */ - max_order = min_t(unsigned int, MAX_ORDER, pageblock_order + 1); - } else { + if (likely(!is_migrate_isolate(migratetype))) { __mod_zone_freepage_state(zone, 1 << order, migratetype); } @@ -708,11 +700,12 @@ static inline void __free_one_page(struct page *page, VM_BUG_ON_PAGE(page_idx & ((1 << order) - 1), page); VM_BUG_ON_PAGE(bad_range(zone, page), page); +continue_merging: while (order < max_order - 1) { buddy_idx = __find_buddy_index(page_idx, order); buddy = page + (buddy_idx - page_idx); if (!page_is_buddy(page, buddy, order)) - break; + goto done_merging; /* * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page, * merge with it and move up one order. @@ -729,6 +722,26 @@ static inline void __free_one_page(struct page *page, page_idx = combined_idx; order++; } + if (max_order < MAX_ORDER) { + if (IS_ENABLED(CONFIG_CMA) && + unlikely(has_isolate_pageblock(zone))) { + + int buddy_mt; + + buddy_idx = __find_buddy_index(page_idx, order); + buddy = page + (buddy_idx - page_idx); + buddy_mt = get_pageblock_migratetype(buddy); + + if (migratetype != buddy_mt && + (is_migrate_isolate(migratetype) || + is_migrate_isolate(buddy_mt))) + goto done_merging; + } + max_order++; + goto continue_merging; + } + +done_merging: set_page_order(page, order); /*
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