revert "mm: have order > 0 compaction start off where it left"

This reverts commit 7db8889ab05b ("mm: have order > 0 compaction start
off where it left") and commit de74f1cc ("mm: have order > 0 compaction
start near a pageblock with free pages").  These patches were a good
idea and tests confirmed that they massively reduced the amount of
scanning but the implementation is complex and tricky to understand.  A
later patch will cache what pageblocks should be skipped and
reimplements the concept of compact_cached_free_pfn on top for both
migration and free scanners.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Richard Davies <richard@arachsys.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Avi Kivity <avi@redhat.com>
Acked-by: Rafael Aquini <aquini@redhat.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 5 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ca002b39b9b4..628968c1ccf4 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4490,11 +4490,6 @@ static void __paginginit free_area_init_core(struct pglist_data *pgdat,
 
                 zone->spanned_pages = size;
                 zone->present_pages = realsize;
-#if defined CONFIG_COMPACTION || defined CONFIG_CMA
-                zone->compact_cached_free_pfn = zone->zone_start_pfn +
-                                                zone->spanned_pages;
-                zone->compact_cached_free_pfn &= ~(pageblock_nr_pages-1);
-#endif
 #ifdef CONFIG_NUMA
                 zone->node = nid;
                 zone->min_unmapped_pages = (realsize*sysctl_min_unmapped_ratio)