Revert "mm: compaction: handle incorrect MIGRATE_UNMOVABLE type pageblocks"

This reverts commit 5ceb9ce6fe.

That commit seems to be the cause of the mm compation list corruption
issues that Dave Jones reported.  The locking (or rather, absense
there-of) is dubious, as is the use of the 'page' variable once it has
been found to be outside the pageblock range.

So revert it for now, we can re-visit this for 3.6.  If we even need to:
as Minchan Kim says, "The patch wasn't a bug fix and even test workload
was very theoretical".

Reported-and-tested-by: Dave Jones <davej@redhat.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/internal.h

@@ -94,9 +94,6 @@ extern void putback_lru_page(struct page *page);
 /*
  * in mm/page_alloc.c
  */
-extern void set_pageblock_migratetype(struct page *page, int migratetype);
-extern int move_freepages_block(struct zone *zone, struct page *page,
-				int migratetype);
 extern void __free_pages_bootmem(struct page *page, unsigned int order);
 extern void prep_compound_page(struct page *page, unsigned long order);
 #ifdef CONFIG_MEMORY_FAILURE
@@ -104,7 +101,6 @@ extern bool is_free_buddy_page(struct page *page);
 #endif
 
 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
-#include <linux/compaction.h>
 
 /*
  * in mm/compaction.c
@@ -123,14 +119,11 @@ struct compact_control {
 	unsigned long nr_migratepages;	/* Number of pages to migrate */
 	unsigned long free_pfn;		/* isolate_freepages search base */
 	unsigned long migrate_pfn;	/* isolate_migratepages search base */
-	enum compact_mode mode;		/* Compaction mode */
+	bool sync;			/* Synchronous migration */
 
 	int order;			/* order a direct compactor needs */
 	int migratetype;		/* MOVABLE, RECLAIMABLE etc */
 	struct zone *zone;
-
-	/* Number of UNMOVABLE destination pageblocks skipped during scan */
-	unsigned long nr_pageblocks_skipped;
 };
 
 unsigned long