Messages in this thread | | | Date | Wed, 23 Nov 2011 09:19:33 +0000 | From | Mel Gorman <> | Subject | Re: [PATCH 5/7] mm: compaction: make isolate_lru_page() filter-aware again |
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On Wed, Nov 23, 2011 at 02:30:18AM +0900, Minchan Kim wrote: > > <SNIP> > > + /* > > + * To minimise LRU disruption, the caller can indicate that it only > > + * wants to isolate pages it will be able to operate on without > > + * blocking - clean pages for the most part. > > + * > > + * ISOLATE_CLEAN means that only clean pages should be isolated. This > > + * is used by reclaim when it is cannot write to backing storage > > + * > > + * ISOLATE_ASYNC_MIGRATE is used to indicate that it only wants to pages > > + * that it is possible to migrate without blocking with a ->migratepage > > + * handler > > + */ > > + if (mode & (ISOLATE_CLEAN|ISOLATE_ASYNC_MIGRATE)) { > > + /* All the caller can do on PageWriteback is block */ > > + if (PageWriteback(page)) > > + return ret; > > + > > + if (PageDirty(page)) { > > + struct address_space *mapping; > > + > > + /* ISOLATE_CLEAN means only clean pages */ > > + if (mode & ISOLATE_CLEAN) > > + return ret; > > + > > + /* > > + * Only the ->migratepage callback knows if a dirty > > + * page can be migrated without blocking. Skip the > > + * page unless there is a ->migratepage callback. > > + */ > > + mapping = page_mapping(page); > > + if (!mapping || !mapping->a_ops->migratepage) > > I didn't review 4/7 carefully yet.
Thanks for reviewing the others.
> In case of page_mapping is NULL, move_to_new_page calls migrate_page > which is non-blocking function. So, I guess it could be migrated without blocking. >
Well spotted
/* * Only pages without mappings or that have a * ->migratepage callback are possible to * migrate without blocking */ mapping = page_mapping(page); if (mapping && !mapping->a_ops->migratepage) return ret;
-- Mel Gorman SUSE Labs
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