mm/compaction: disallow high-order page for migration target
commit 7d348b9ea6
upstream.
Purpose of compaction is to get a high order page. Currently, if we
find high-order page while searching migration target page, we break it
to order-0 pages and use them as migration target. It is contrary to
purpose of compaction, so disallow high-order page to be used for
migration target.
Additionally, clean-up logic in suitable_migration_target() to simplify
the code. There is no functional changes from this clean-up.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -217,21 +217,12 @@ static inline bool compact_trylock_irqsave(spinlock_t *lock,
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/* Returns true if the page is within a block suitable for migration to */
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static bool suitable_migration_target(struct page *page)
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{
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int migratetype = get_pageblock_migratetype(page);
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/* Don't interfere with memory hot-remove or the min_free_kbytes blocks */
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if (migratetype == MIGRATE_RESERVE)
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return false;
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if (is_migrate_isolate(migratetype))
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return false;
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/* If the page is a large free page, then allow migration */
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/* If the page is a large free page, then disallow migration */
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if (PageBuddy(page) && page_order(page) >= pageblock_order)
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return true;
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return false;
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/* If the block is MIGRATE_MOVABLE or MIGRATE_CMA, allow migration */
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if (migrate_async_suitable(migratetype))
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if (migrate_async_suitable(get_pageblock_migratetype(page)))
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return true;
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/* Otherwise skip the block */
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