From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f180.google.com (mail-pd0-f180.google.com [209.85.192.180]) by kanga.kvack.org (Postfix) with ESMTP id 371706B0037 for ; Mon, 3 Feb 2014 21:50:58 -0500 (EST) Received: by mail-pd0-f180.google.com with SMTP id x10so7671121pdj.11 for ; Mon, 03 Feb 2014 18:50:57 -0800 (PST) Received: from mail-pd0-x22d.google.com (mail-pd0-x22d.google.com [2607:f8b0:400e:c02::22d]) by mx.google.com with ESMTPS id fu1si22677262pbc.254.2014.02.03.18.50.57 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 03 Feb 2014 18:50:57 -0800 (PST) Received: by mail-pd0-f173.google.com with SMTP id y10so7639732pdj.4 for ; Mon, 03 Feb 2014 18:50:57 -0800 (PST) Date: Mon, 3 Feb 2014 18:50:54 -0800 (PST) From: David Rientjes Subject: Re: [patch] mm, compaction: avoid isolating pinned pages fix In-Reply-To: <20140204021533.GA14924@lge.com> Message-ID: References: <20140203095329.GH6732@suse.de> <20140204000237.GA17331@lge.com> <20140204015332.GA14779@lge.com> <20140204021533.GA14924@lge.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Mel Gorman , Andrew Morton , Rik van Riel , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Tue, 4 Feb 2014, Joonsoo Kim wrote: > > > Okay. It can't fix your situation. Anyway, *normal* anon pages may be mapped > > > and have positive page_count(), so your code such as > > > '!page_mapping(page) && page_count(page)' makes compaction skip these *normal* > > > anon pages and this is incorrect behaviour. > > > > > > > So how does that work with migrate_page_move_mapping() which demands > > page_count(page) == 1 and the get_page_unless_zero() in > > __isolate_lru_page()? > > Before doing migrate_page_move_mapping(), try_to_unmap() is called so that all > mapping is unmapped. Then, remained page_count() is 1 which is grabbed by > __isolate_lru_page(). Am I missing something? > Ah, good point. I wonder if we can get away with page_count(page) - page_mapcount(page) > 1 to avoid the get_user_pages() pin? -- 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