[PATCH] mm: huge_memory: don't start_stop_khugepaged for non-PMD THP

[Barry Song <21cnbao@gmail.com>]

From: Barry Song <v-songbaohua@oppo.com>

khugepaged will be automatically started when PMD-sized THP is enabled
(either of the per-size anon control or the top-level control are set
to "always" or "madvise"), and it'll be automatically shutdown when
PMD-sized THP is disabled (when both the per-size anon control and the
top-level control are "never").

It seems unnecessary to call start_stop_khugepaged() for non-PMD THP,
as it would only waste CPU time.

Cc: Lance Yang <ioworker0@gmail.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
---
 mm/huge_memory.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 41460847988c..bd365e35acf7 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -514,7 +514,7 @@ static ssize_t thpsize_enabled_store(struct kobject *kobj,
 	} else
 		ret = -EINVAL;
 
-	if (ret > 0) {
+	if (ret > 0 && order == HPAGE_PMD_ORDER) {
 		int err;
 
 		err = start_stop_khugepaged();
-- 
2.34.1