From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f47.google.com (mail-pa0-f47.google.com [209.85.220.47]) by kanga.kvack.org (Postfix) with ESMTP id 029D49003C7 for ; Mon, 20 Jul 2015 07:54:16 -0400 (EDT) Received: by pacan13 with SMTP id an13so101437423pac.1 for ; Mon, 20 Jul 2015 04:54:15 -0700 (PDT) Received: from mail-pd0-x22e.google.com (mail-pd0-x22e.google.com. [2607:f8b0:400e:c02::22e]) by mx.google.com with ESMTPS id dt1si35537664pdb.120.2015.07.20.04.54.15 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 20 Jul 2015 04:54:15 -0700 (PDT) Received: by pdbnt7 with SMTP id nt7so29992748pdb.0 for ; Mon, 20 Jul 2015 04:54:14 -0700 (PDT) Date: Mon, 20 Jul 2015 20:54:13 +0900 From: Minchan Kim Subject: Re: [PATCH 2/2] mm/page_owner: set correct gfp_mask on page_owner Message-ID: <20150720115352.GA13474@bgram> References: <1436942039-16897-1-git-send-email-iamjoonsoo.kim@lge.com> <1436942039-16897-2-git-send-email-iamjoonsoo.kim@lge.com> <20150716000613.GE988@bgram> <55ACDB3B.8010607@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <55ACDB3B.8010607@suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: Joonsoo Kim , Andrew Morton , Mel Gorman , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Joonsoo Kim On Mon, Jul 20, 2015 at 01:27:55PM +0200, Vlastimil Babka wrote: > On 07/16/2015 02:06 AM, Minchan Kim wrote: > >On Wed, Jul 15, 2015 at 03:33:59PM +0900, Joonsoo Kim wrote: > >>@@ -2003,7 +2005,7 @@ 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, 0); > >>+ set_page_owner(page, order, __GFP_MOVABLE); > > > >It seems the reason why __GFP_MOVABLE is okay is that __isolate_free_page > >works on a free page on MIGRATE_MOVABLE|MIGRATE_CMA's pageblock. But if we > >break the assumption in future, here is broken again? > > I didn't study the page owner code yet and I'm catching up after > vacation, but I share your concern. But I don't think the > correctness depends on the pageblock we are isolating from. I think > the assumption is that the isolated freepage will be used as a > target for migration, and that only movable pages can be > successfully migrated (but also CMA pages, and that information can > be lost?). However there are also efforts to allow migrate e.g. > driver pages that won't be marked as movable. And I'm not sure which > migratetype are balloon pages which already have special migration > code. I am one of people who want to migrate driver pages from compaction from zram point of view so I agree with you. However, If I make zram support migratepages, I will use __GFP_MOVABLE. So, I'm not sure there is any special driver that it can support migrate via migratepage but it doesn't set __GFP_MOVABLE. Having said that, I support your opinion because __GFP_MOVABLE is not only gfp mask for allocating so we should take care of complete gfp mask from original page. > > So what I would think (without knowing all details) that the page > owner info should be transferred during page migration with all the > other flags, and shouldn't concern __isolate_free_page() at all? > I agree. 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