[PATCH] revert mm: compaction: iron out isolate_freepages_block()and isolate_freepages_range()

[Minchan Kim]

[1] made bug on CMA.
The nr_scanned should be never equal to total_isolated for successful CMA.
This patch reverts part of the patch.

[1] mm: compaction: iron out isolate_freepages_block() and isolate_freepages_range()

Cc: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
---
 mm/compaction.c |   29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index 5037399..7721197 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -269,13 +269,14 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
 		int isolated, i;
 		struct page *page = cursor;
 
-		nr_scanned++;
 		if (!pfn_valid_within(blockpfn))
-			continue;
+			goto strict_check;
+		nr_scanned++;
+
 		if (!valid_page)
 			valid_page = page;
 		if (!PageBuddy(page))
-			continue;
+			goto strict_check;
 
 		/*
 		 * The zone lock must be held to isolate freepages.
@@ -296,12 +297,12 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
 
 		/* Recheck this is a buddy page under lock */
 		if (!PageBuddy(page))
-			continue;
+			goto strict_check;
 
 		/* Found a free page, break it into order-0 pages */
 		isolated = split_free_page(page);
 		if (!isolated && strict)
-			break;
+			goto strict_check;
 		total_isolated += isolated;
 		for (i = 0; i < isolated; i++) {
 			list_add(&page->lru, freelist);
@@ -313,18 +314,20 @@ static unsigned long isolate_freepages_block(struct compact_control *cc,
 			blockpfn += isolated - 1;
 			cursor += isolated - 1;
 		}
+
+		continue;
+
+strict_check:
+		/* Abort isolation if the caller requested strict isolation */
+		if (strict) {
+			total_isolated = 0;
+			goto out;
+		}
 	}
 
 	trace_mm_compaction_isolate_freepages(nr_scanned, total_isolated);
 
-	/*
-	 * If strict isolation is requested by CMA then check that all the
-	 * pages scanned were isolated. If there were any failures, 0 is
-	 * returned and CMA will fail.
-	 */
-	if (strict && nr_scanned != total_isolated)
-		total_isolated = 0;
-
+out:
 	if (locked)
 		spin_unlock_irqrestore(&cc->zone->lock, flags);
 
-- 
1.7.9.5



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-- 
Kind regards,
Minchan Kim
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