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From:   Baolin Wang <baolin.wang@linux.alibaba.com>
To:     akpm@linux-foundation.org
Cc:     shy828301@gmail.com, baolin.wang@linux.alibaba.com,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: [PATCH] mm: migrate: Correct the hugetlb migration stats
Date:   Fri, 29 Oct 2021 15:42:37 +0800
Message-Id: <b35e54802a9a82d03d24845b463e9d9a68f7fd6b.1635491660.git.baolin.wang@linux.alibaba.com>
Precedence: bulk

Now hugetlb migration is also available for some scenarios, such as
soft offling or memory compaction. So we should correct the migration
stats for hugetlb with using compound_nr() instead of thp_nr_pages()
to get the number of pages.

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
---
 mm/migrate.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index a11e948..2b45a29 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1475,7 +1475,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
 			 * during migration.
 			 */
 			is_thp = PageTransHuge(page) && !PageHuge(page);
-			nr_subpages = thp_nr_pages(page);
+			nr_subpages = compound_nr(page);
 			cond_resched();
 
 			if (PageHuge(page))
@@ -1540,7 +1540,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
 					nr_failed += nr_subpages;
 					goto out;
 				}
-				nr_failed++;
+				nr_failed += nr_subpages;
 				goto out;
 			case -EAGAIN:
 				if (is_thp) {
@@ -1550,14 +1550,14 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
 				retry++;
 				break;
 			case MIGRATEPAGE_SUCCESS:
+				nr_succeeded += nr_subpages;
 				if (is_thp) {
 					nr_thp_succeeded++;
-					nr_succeeded += nr_subpages;
 					break;
 				}
-				nr_succeeded++;
 				break;
 			default:
+				nr_failed += nr_subpages;
 				/*
 				 * Permanent failure (-EBUSY, etc.):
 				 * unlike -EAGAIN case, the failed page is
@@ -1566,10 +1566,8 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
 				 */
 				if (is_thp) {
 					nr_thp_failed++;
-					nr_failed += nr_subpages;
 					break;
 				}
-				nr_failed++;
 				break;
 			}
 		}
-- 
1.8.3.1