Messages in this thread | | | 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 |
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On Wed, 04 Jul 2012 11:34:09 +0900 Minchan Kim <minchan@kernel.org> 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?
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