From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752523AbcFCKXM (ORCPT ); Fri, 3 Jun 2016 06:23:12 -0400 Received: from mx2.suse.de ([195.135.220.15]:55859 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751649AbcFCKXL (ORCPT ); Fri, 3 Jun 2016 06:23:11 -0400 Subject: Re: [PATCH v2 2/7] mm/page_owner: initialize page owner without holding the zone lock To: js1304@gmail.com, Andrew Morton References: <1464230275-25791-1-git-send-email-iamjoonsoo.kim@lge.com> <1464230275-25791-2-git-send-email-iamjoonsoo.kim@lge.com> Cc: mgorman@techsingularity.net, Minchan Kim , Alexander Potapenko , Hugh Dickins , Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Joonsoo Kim From: Vlastimil Babka Message-ID: Date: Fri, 3 Jun 2016 12:23:06 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 MIME-Version: 1.0 In-Reply-To: <1464230275-25791-2-git-send-email-iamjoonsoo.kim@lge.com> Content-Type: text/plain; charset=iso-8859-2; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/26/2016 04:37 AM, js1304@gmail.com wrote: > From: Joonsoo Kim > > It's not necessary to initialized page_owner with holding the zone lock. > It would cause more contention on the zone lock although it's not > a big problem since it is just debug feature. But, it is better > than before so do it. This is also preparation step to use stackdepot > in page owner feature. Stackdepot allocates new pages when there is no > reserved space and holding the zone lock in this case will cause deadlock. > > Signed-off-by: Joonsoo Kim > --- > mm/compaction.c | 3 +++ > mm/page_alloc.c | 2 -- > mm/page_isolation.c | 9 ++++++--- > 3 files changed, 9 insertions(+), 5 deletions(-) > > diff --git a/mm/compaction.c b/mm/compaction.c > index 8e013eb..6043ef8 100644 > --- a/mm/compaction.c > +++ b/mm/compaction.c > @@ -20,6 +20,7 @@ > #include > #include > #include > +#include > #include "internal.h" > > #ifdef CONFIG_COMPACTION > @@ -80,6 +81,8 @@ static void map_pages(struct list_head *list) > arch_alloc_page(page, order); > kernel_map_pages(page, nr_pages, 1); > kasan_alloc_pages(page, order); > + > + set_page_owner(page, order, __GFP_MOVABLE); > if (order) > split_page(page, order); > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 5134f46..1b1ca57 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2507,8 +2507,6 @@ int __isolate_free_page(struct page *page, unsigned int order) > zone->free_area[order].nr_free--; > rmv_page_order(page); > > - set_page_owner(page, order, __GFP_MOVABLE); > - > /* Set the pageblock if the isolated page is at least a pageblock */ > if (order >= pageblock_order - 1) { > struct page *endpage = page + (1 << order) - 1; > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index 612122b..927f5ee 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -7,6 +7,7 @@ > #include > #include > #include > +#include > #include "internal.h" > > #define CREATE_TRACE_POINTS > @@ -108,8 +109,6 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype) > if (pfn_valid_within(page_to_pfn(buddy)) && > !is_migrate_isolate_page(buddy)) { > __isolate_free_page(page, order); > - kernel_map_pages(page, (1 << order), 1); > - set_page_refcounted(page); > isolated_page = page; > } > } > @@ -128,8 +127,12 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype) > zone->nr_isolate_pageblock--; > out: > spin_unlock_irqrestore(&zone->lock, flags); > - if (isolated_page) > + if (isolated_page) { > + kernel_map_pages(page, (1 << order), 1); So why we don't need the other stuff done by e.g. map_pages()? For example arch_alloc_page() and kasan_alloc_pages(). Maybe kasan_free_pages() (called below via __free_pages() I assume) now doesn't check if the allocation part was done. But maybe it will start doing that? See how the multiple places doing similar stuff is fragile? :( > + set_page_refcounted(page); > + set_page_owner(page, order, __GFP_MOVABLE); > __free_pages(isolated_page, order); This mixing of "isolated_page" and "page" is not a bug, but quite ugly. Can't isolated_page variable just be a bool? > + } > } > > static inline struct page * >