linux-kernel - [PATCH v2 8/8] mm: migrate: remove isolated variable in add_page_for

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Date:   Mon, 21 Aug 2023 19:56:24 +0800
From:   Kefeng Wang <wangkefeng.wang@...wei.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     <willy@...radead.org>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <ying.huang@...el.com>,
        <david@...hat.com>, Zi Yan <ziy@...dia.com>,
        Mike Kravetz <mike.kravetz@...cle.com>, <hughd@...gle.com>,
        Kefeng Wang <wangkefeng.wang@...wei.com>
Subject: [PATCH v2 8/8] mm: migrate: remove isolated variable in add_page_for_migration()

Directly check the return of isolate_hugetlb() and folio_isolate_lru()
to remove isolated variable, also setup err = -EBUSY in advance before
isolation, and update err only when successfully queued for migration,
which could help us to unify and simplify code a bit.

Signed-off-by: Kefeng Wang <wangkefeng.wang@...wei.com>
---
 mm/migrate.c | 11 ++++-------
 1 file changed, 4 insertions(+), 7 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index e8c3fb8974f9..9bbd9018ece7 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2059,7 +2059,6 @@ static int add_page_for_migration(struct mm_struct *mm, const void __user *p,
 	struct page *page;
 	struct folio *folio;
 	int err;
-	bool isolated;
 
 	mmap_read_lock(mm);
 	addr = (unsigned long)untagged_addr_remote(mm, p);
@@ -2092,15 +2091,13 @@ static int add_page_for_migration(struct mm_struct *mm, const void __user *p,
 	if (page_mapcount(page) > 1 && !migrate_all)
 		goto out_putfolio;
 
+	err = -EBUSY;
 	if (folio_test_hugetlb(folio)) {
-		isolated = isolate_hugetlb(folio, pagelist);
-		err = isolated ? 1 : -EBUSY;
+		if (isolate_hugetlb(folio, pagelist))
+			err = 1;
 	} else {
-		isolated = folio_isolate_lru(folio);
-		if (!isolated) {
-			err = -EBUSY;
+		if (!folio_isolate_lru(folio))
 			goto out_putfolio;
-		}
 
 		err = 1;
 		list_add_tail(&folio->lru, pagelist);
-- 
2.41.0