From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f175.google.com (mail-wi0-f175.google.com [209.85.212.175]) by kanga.kvack.org (Postfix) with ESMTP id 58F4D6B0035 for ; Thu, 17 Jul 2014 05:28:39 -0400 (EDT) Received: by mail-wi0-f175.google.com with SMTP id ho1so7587719wib.14 for ; Thu, 17 Jul 2014 02:28:38 -0700 (PDT) Received: from mx2.suse.de (cantor2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id ez4si24828658wic.77.2014.07.17.02.28.29 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 17 Jul 2014 02:28:30 -0700 (PDT) Message-ID: <53C793F0.6030707@suse.cz> Date: Thu, 17 Jul 2014 11:14:24 +0200 From: Vlastimil Babka MIME-Version: 1.0 Subject: Re: [PATCH 00/10] fix freepage count problems due to memory isolation References: <1404460675-24456-1-git-send-email-iamjoonsoo.kim@lge.com> <53B6C947.1070603@suse.cz> <20140707044932.GA29236@js1304-P5Q-DELUXE> <53BAAFA5.9070403@suse.cz> <20140714062222.GA11317@js1304-P5Q-DELUXE> <53C3A7A5.9060005@suse.cz> <20140715082828.GM11317@js1304-P5Q-DELUXE> <53C4E813.7020108@suse.cz> <20140716084333.GA20359@js1304-P5Q-DELUXE> <53C65E92.2000606@suse.cz> <20140717061205.GA22418@js1304-P5Q-DELUXE> In-Reply-To: <20140717061205.GA22418@js1304-P5Q-DELUXE> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Andrew Morton , "Kirill A. Shutemov" , Rik van Riel , Peter Zijlstra , Mel Gorman , Johannes Weiner , Minchan Kim , Yasuaki Ishimatsu , Zhang Yanfei , "Srivatsa S. Bhat" , 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, Lisa Du , linux-kernel@vger.kernel.org On 07/17/2014 08:12 AM, Joonsoo Kim wrote: >> >> Hm I see. So what if it wasn't a special pcplist, but a special "free list" >> where the pages would be just linked together as on pcplist, regardless of >> order, and would not merge until the CPU that drives the memory isolation >> process decides it is safe to flush them away. That would remove the need for >> IPI's and provide the same guarantees I think. > > Looks good. It would work. I think that your solution is better than mine. > I will implement it and test. Thanks. But maybe there's still a good use for marking pages specially as isolated, and not PageBuddy with freepage_migratetype set to MIGRATE_ISOLATE. Why do we buddy-merge them anyway? I don't think CMA or memory offlining benefits from that, and it only makes the code more complex? So maybe we could split isolated buddy pages to order-0 marked as PageIsolated and have a single per-zone list instead of order-based freelists? >> Do we really need to check PageBuddy()? Could a page get marked as PageIsolate() >> but still go to normal list instead of isolate list? > > Checking PageBuddy() is used for identifying page linked in normal > list. Ah right, forgot it walks by pfn scanning, not by traversing the free list. > 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 > -- 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