From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx174.postini.com [74.125.245.174]) by kanga.kvack.org (Postfix) with SMTP id 7574F6B0071 for ; Wed, 4 Jul 2012 03:40:40 -0400 (EDT) Date: Wed, 4 Jul 2012 00:42:19 -0700 From: Andrew Morton Subject: Re: [PATCH -mm v2] mm: have order > 0 compaction start off where it left Message-Id: <20120704004219.47d0508d.akpm@linux-foundation.org> In-Reply-To: <4FF3ABA1.3070808@kernel.org> References: <20120628135520.0c48b066@annuminas.surriel.com> <20120628135940.2c26ada9.akpm@linux-foundation.org> <4FECCB89.2050400@redhat.com> <20120628143546.d02d13f9.akpm@linux-foundation.org> <1341250950.16969.6.camel@lappy> <4FF2435F.2070302@redhat.com> <20120703101024.GG13141@csn.ul.ie> <20120703144808.4daa4244.akpm@linux-foundation.org> <4FF3ABA1.3070808@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Mel Gorman , Rik van Riel , Sasha Levin , linux-mm@kvack.org, linux-kernel@vger.kernel.org, jaschut@sandia.gov, kamezawa.hiroyu@jp.fujitsu.com, Dave Jones On Wed, 04 Jul 2012 11:34:09 +0900 Minchan Kim wrote: > > The rest of this patch takes care to ensure that > > ->compact_cached_free_pfn is aligned to pageblock_nr_pages. But it now > > appears that this particular site will violate that. > > > > What's up? Do we need to fix this site, or do we remove all that > > make-compact_cached_free_pfn-aligned code? > > > I vote removing the warning because it doesn't related to Rik's incremental compaction. > Let's see. > > high_pfn = min(low_pfn, pfn) = cc->migrate_pfn + pageblock_nr_pages. > In here, cc->migrate_pfn isn't necessarily pageblock aligined. > So if we don't consider compact_cached_free_pfn, it can hit. > > static void isolate_freepages() > { > high_pfn = min(low_pfn, pfn) = cc->migrate_pfn + pageblock_nr_pages; > for (..) { > ... > WARN_ON_ONCE(high_pfn & (pageblock_nr_pages - 1)); > > } > } Please, look at the patch. In numerous places it is aligning compact_cached_free_pfn to a multiple of pageblock_nr_pages. But in one place it doesn't do that. So are all those alignment operations necessary? -- 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