[RFC PATCH 2/8] mm, compaction: skip_on_failure only for MIGRATE_MOVABLE allocations

[Vlastimil Babka <vbabka@suse.cz>]

When migration scanner skips the rest of cc->order aligned block on isolation
failure, it avoids making migrations that cannot help the allocation at hand to
succeed, but the potential downside is not freeing pages in !MIGRATE_MOVABLE
pageblocks which could otherwise prevent allocations of same migratetype from
fallback to other pageblock types. Therefore let's restrict the skipping only
to MIGRATE_MOVABLE allocations, which in the async direct compaction mode only
scan MIGRATE_MOVABLE pageblocks.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
 mm/compaction.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index ce73badad464..95b8b5ae59c5 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -720,7 +720,8 @@ isolate_migratepages_block(struct compact_control *cc, unsigned long low_pfn,
 	if (compact_should_abort(cc))
 		return 0;
 
-	if (cc->direct_compaction && (cc->mode == MIGRATE_ASYNC)) {
+	if (cc->direct_compaction && (cc->mode == MIGRATE_ASYNC) &&
+			cc->migratetype == MIGRATE_MOVABLE) {
 		skip_on_failure = true;
 		next_skip_pfn = block_end_pfn(low_pfn, cc->order);
 	}
-- 
2.15.1

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