From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f45.google.com (mail-pa0-f45.google.com [209.85.220.45]) by kanga.kvack.org (Postfix) with ESMTP id 35C5A900021 for ; Tue, 28 Oct 2014 03:36:28 -0400 (EDT) Received: by mail-pa0-f45.google.com with SMTP id lf10so141511pab.4 for ; Tue, 28 Oct 2014 00:36:27 -0700 (PDT) Received: from lgemrelse7q.lge.com (LGEMRELSE7Q.lge.com. [156.147.1.151]) by mx.google.com with ESMTP id bk16si635605pdb.70.2014.10.28.00.36.26 for ; Tue, 28 Oct 2014 00:36:27 -0700 (PDT) Date: Tue, 28 Oct 2014 16:37:45 +0900 From: Joonsoo Kim Subject: Re: [PATCH v4 3/4] mm/page_alloc: move migratetype recheck logic to __free_one_page() Message-ID: <20141028073745.GD27813@js1304-P5Q-DELUXE> References: <1414051821-12769-1-git-send-email-iamjoonsoo.kim@lge.com> <1414051821-12769-4-git-send-email-iamjoonsoo.kim@lge.com> <544E2117.9000809@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <544E2117.9000809@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Andrew Morton , "Kirill A. Shutemov" , Rik van Riel , Peter Zijlstra , Mel Gorman , Johannes Weiner , Minchan Kim , Yasuaki Ishimatsu , Zhang Yanfei , Tang Chen , Naoya Horiguchi , Bartlomiej Zolnierkiewicz , Wen Congyang , Marek Szyprowski , Michal Nazarewicz , Laura Abbott , Heesub Shin , "Aneesh Kumar K.V" , Ritesh Harjani , t.stanislaws@samsung.com, Gioh Kim , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org On Mon, Oct 27, 2014 at 11:40:23AM +0100, Vlastimil Babka wrote: > On 10/23/2014 10:10 AM, Joonsoo Kim wrote: > > All the caller of __free_one_page() has similar migratetype recheck logic, > > so we can move it to __free_one_page(). This reduce line of code and help > > future maintenance. This is also preparation step for "mm/page_alloc: > > restrict max order of merging on isolated pageblock" which fix the > > freepage accouting problem on freepage with more than pageblock order. > > > > Cc: > > Signed-off-by: Joonsoo Kim > > --- > > mm/page_alloc.c | 24 ++++++++---------------- > > 1 file changed, 8 insertions(+), 16 deletions(-) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 5d2f807..433f92c 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -579,7 +579,15 @@ static inline void __free_one_page(struct page *page, > > return; > > > > VM_BUG_ON(migratetype == -1); > > + if (unlikely(has_isolate_pageblock(zone) || > > + is_migrate_isolate(migratetype))) { > > Since the v4 change of patch 1, this now adds > is_migrate_isolate(migratetype) also for the free_pcppages_bulk path, > where it's not needed? Yes, you are right. But, patch 4 needs is_migrate_isolate() check in __free_one_page(). > > > + migratetype = get_pfnblock_migratetype(page, pfn); > > + if (is_migrate_isolate(migratetype)) > > + goto skip_counting; > > + } > > + __mod_zone_freepage_state(zone, 1 << order, migratetype); > > > > +skip_counting: > > page_idx = pfn & ((1 << MAX_ORDER) - 1); > > > > VM_BUG_ON_PAGE(page_idx & ((1 << order) - 1), page); > > @@ -725,14 +733,7 @@ static void free_pcppages_bulk(struct zone *zone, int count, > > /* must delete as __free_one_page list manipulates */ > > list_del(&page->lru); > > mt = get_freepage_migratetype(page); > > - if (unlikely(has_isolate_pageblock(zone))) { > > - mt = get_pageblock_migratetype(page); > > - if (is_migrate_isolate(mt)) > > - goto skip_counting; > > - } > > - __mod_zone_freepage_state(zone, 1, mt); > > > > -skip_counting: > > /* MIGRATE_MOVABLE list may include MIGRATE_RESERVEs */ > > __free_one_page(page, page_to_pfn(page), zone, 0, mt); > > trace_mm_page_pcpu_drain(page, 0, mt); > > The 'mt' here for the tracepoint is now different. I know it's the same > as before patch 2, but the value introduced by patch 2 is more correct > than the reverting to pre-patch 2 done here. Yes, you are right. I didn't notice that. > This and the introduced check above are maybe minor things, but it makes > me question the value of unifying the check when the conditions in the > two call paths are not completely the same... > > I understand this is also prerequisity for patch 4 in some sense, but if > you are reworking it anyway, then maybe this won't be needed in the end? As mentioned above, is_migrate_isolate() check is needed in __free_one_page() in any case. Reworked patch also needs this. Hmm... I'd like to check isolate migratetype in just one place, but, it seems to be impossible. To correct tracepoint, I will remain the check in each functions. :/ Thanks. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org