[PATCH 3/4] mm/migration: return errno when isolate_huge_page failed

From: Miaohe Lin <linmiaohe@huawei.com>
To: <akpm@linux-foundation.org>
Cc: <mike.kravetz@oracle.com>, <shy828301@gmail.com>,
	<willy@infradead.org>, <ying.huang@intel.com>, <ziy@nvidia.com>,
	<minchan@kernel.org>, <apopple@nvidia.com>,
	<dave.hansen@linux.intel.com>, <o451686892@gmail.com>,
	<jhubbard@nvidia.com>, <peterx@redhat.com>,
	<naoya.horiguchi@nec.com>, <mhocko@suse.com>, <riel@redhat.com>,
	<osalvador@suse.de>, <david@redhat.com>, <sfr@canb.auug.org.au>,
	<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
	<linmiaohe@huawei.com>
Subject: [PATCH 3/4] mm/migration: return errno when isolate_huge_page failed
Date: Sat, 9 Apr 2022 15:38:45 +0800	[thread overview]
Message-ID: <20220409073846.22286-4-linmiaohe@huawei.com> (raw)
In-Reply-To: <20220409073846.22286-1-linmiaohe@huawei.com>

We might fail to isolate huge page due to e.g. the page is under migration
which cleared HPageMigratable. So we should return -EBUSY in this case
rather than always return 1 which could confuse the user.

Fixes: e8db67eb0ded ("mm: migrate: move_pages() supports thp migration")
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 mm/migrate.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 381963231a62..044656a14ae2 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1632,10 +1632,8 @@ static int add_page_for_migration(struct mm_struct *mm, unsigned long addr,
 		goto out_putpage;
 
 	if (PageHuge(page)) {
-		if (PageHead(page)) {
-			isolate_huge_page(page, pagelist);
-			err = 1;
-		}
+		if (PageHead(page))
+			err = isolate_huge_page(page, pagelist) ? 1 : -EBUSY;
 	} else {
 		struct page *head;
 
-- 
2.23.0


