Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752708AbcCGM7Y (ORCPT ); Mon, 7 Mar 2016 07:59:24 -0500 Received: from mx2.suse.de ([195.135.220.15]:38771 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752180AbcCGM7Q (ORCPT ); Mon, 7 Mar 2016 07:59:16 -0500 Subject: Re: Suspicious error for CMA stress test To: Joonsoo Kim , Hanjun Guo References: <56D6F008.1050600@huawei.com> <56D79284.3030009@redhat.com> <56D832BD.5080305@huawei.com> <20160304020232.GA12036@js1304-P5Q-DELUXE> <20160304043232.GC12036@js1304-P5Q-DELUXE> <56D92595.60709@huawei.com> <20160304063807.GA13317@js1304-P5Q-DELUXE> <56D93ABE.9070406@huawei.com> <20160307043442.GB24602@js1304-P5Q-DELUXE> Cc: Laura Abbott , "linux-arm-kernel@lists.infradead.org" , "linux-kernel@vger.kernel.org" , Andrew Morton , Sasha Levin , Laura Abbott , qiuxishi , Catalin Marinas , Will Deacon , Arnd Bergmann , "thunder.leizhen@huawei.com" , dingtinahong , chenjie6@huawei.com, "linux-mm@kvack.org" From: Vlastimil Babka Message-ID: <56DD7B20.1020508@suse.cz> Date: Mon, 7 Mar 2016 13:59:12 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <20160307043442.GB24602@js1304-P5Q-DELUXE> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4809 Lines: 108 On 03/07/2016 05:34 AM, Joonsoo Kim wrote: > On Fri, Mar 04, 2016 at 03:35:26PM +0800, Hanjun Guo wrote: >>> Sad to hear that. >>> >>> Could you tell me your system's MAX_ORDER and pageblock_order? >>> >> >> MAX_ORDER is 11, pageblock_order is 9, thanks for your help! I thought that CMA regions/operations (and isolation IIRC?) were supposed to be MAX_ORDER aligned exactly to prevent needing these extra checks for buddy merging. So what's wrong? > Hmm... that's same with me. > > Below is similar fix that prevents buddy merging when one of buddy's > migrate type, but, not both, is MIGRATE_ISOLATE. In fact, I have > no idea why previous fix (more correct fix) doesn't work for you. > (It works for me.) But, maybe there is a bug on the fix > so I make new one which is more general form. Please test it. > > Thanks. > > ---------->8------------- > From dd41e348572948d70b935fc24f82c096ff0fb417 Mon Sep 17 00:00:00 2001 > From: Joonsoo Kim > Date: Fri, 4 Mar 2016 13:28:17 +0900 > Subject: [PATCH] mm/cma: fix race > > Signed-off-by: Joonsoo Kim > --- > mm/page_alloc.c | 33 +++++++++++++++++++-------------- > 1 file changed, 19 insertions(+), 14 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index c6c38ed..d80d071 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -620,8 +620,8 @@ static inline void rmv_page_order(struct page *page) > * > * For recording page's order, we use page_private(page). > */ > -static inline int page_is_buddy(struct page *page, struct page *buddy, > - unsigned int order) > +static inline int page_is_buddy(struct zone *zone, struct page *page, > + struct page *buddy, unsigned int order) > { > if (!pfn_valid_within(page_to_pfn(buddy))) > return 0; > @@ -644,6 +644,20 @@ static inline int page_is_buddy(struct page *page, struct page *buddy, > if (page_zone_id(page) != page_zone_id(buddy)) > return 0; > > + if (IS_ENABLED(CONFIG_CMA) && > + unlikely(has_isolate_pageblock(zone)) && > + unlikely(order >= pageblock_order)) { > + int page_mt, buddy_mt; > + > + page_mt = get_pageblock_migratetype(page); > + buddy_mt = get_pageblock_migratetype(buddy); > + > + if (page_mt != buddy_mt && > + (is_migrate_isolate(page_mt) || > + is_migrate_isolate(buddy_mt))) > + return 0; > + } > + > VM_BUG_ON_PAGE(page_count(buddy) != 0, buddy); > > return 1; > @@ -691,17 +705,8 @@ static inline void __free_one_page(struct page *page, > 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 (!is_migrate_isolate(migratetype)) > __mod_zone_freepage_state(zone, 1 << order, migratetype); > - } > > page_idx = pfn & ((1 << max_order) - 1); > > @@ -711,7 +716,7 @@ static inline void __free_one_page(struct page *page, > 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)) > + if (!page_is_buddy(zone, page, buddy, order)) > break; > /* > * Our buddy is free or it is CONFIG_DEBUG_PAGEALLOC guard page, > @@ -745,7 +750,7 @@ static inline void __free_one_page(struct page *page, > higher_page = page + (combined_idx - page_idx); > buddy_idx = __find_buddy_index(combined_idx, order + 1); > higher_buddy = higher_page + (buddy_idx - combined_idx); > - if (page_is_buddy(higher_page, higher_buddy, order + 1)) { > + if (page_is_buddy(zone, higher_page, higher_buddy, order + 1)) { > list_add_tail(&page->lru, > &zone->free_area[order].free_list[migratetype]); > goto out; >