linux-kernel - [v3 PATCH 4/5] mm: migrate: clean up migrate_prep{

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Message-Id: <20201113205359.556831-5-shy828301@gmail.com>
Date:   Fri, 13 Nov 2020 12:53:58 -0800
From:   Yang Shi <shy828301@...il.com>
To:     mhocko@...e.com, ziy@...dia.com, songliubraving@...com,
        mgorman@...e.de, jack@...e.cz, willy@...radead.org,
        akpm@...ux-foundation.org
Cc:     shy828301@...il.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: [v3 PATCH 4/5] mm: migrate: clean up migrate_prep{_local}

The migrate_prep{_local} never fails, so it is pointless to have return
value and check the return value.

Reviewed-by: Zi Yan <ziy@...dia.com>
Signed-off-by: Yang Shi <shy828301@...il.com>
---
 include/linux/migrate.h | 4 ++--
 mm/mempolicy.c          | 8 ++------
 mm/migrate.c            | 8 ++------
 3 files changed, 6 insertions(+), 14 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 0f8d1583fa8e..4594838a0f7c 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -45,8 +45,8 @@ extern struct page *alloc_migration_target(struct page *page, unsigned long priv
 extern int isolate_movable_page(struct page *page, isolate_mode_t mode);
 extern void putback_movable_page(struct page *page);
 
-extern int migrate_prep(void);
-extern int migrate_prep_local(void);
+extern void migrate_prep(void);
+extern void migrate_prep_local(void);
 extern void migrate_page_states(struct page *newpage, struct page *page);
 extern void migrate_page_copy(struct page *newpage, struct page *page);
 extern int migrate_huge_page_move_mapping(struct address_space *mapping,
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 3ca4898f3f24..8cf96bd21341 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1114,9 +1114,7 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
 	int err;
 	nodemask_t tmp;
 
-	err = migrate_prep();
-	if (err)
-		return err;
+	migrate_prep();
 
 	mmap_read_lock(mm);
 
@@ -1315,9 +1313,7 @@ static long do_mbind(unsigned long start, unsigned long len,
 
 	if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
 
-		err = migrate_prep();
-		if (err)
-			goto mpol_out;
+		migrate_prep();
 	}
 	{
 		NODEMASK_SCRATCH(scratch);
diff --git a/mm/migrate.c b/mm/migrate.c
index 18cc1ef0e447..4d3d173a1706 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -62,7 +62,7 @@
  * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
  * undesirable, use migrate_prep_local()
  */
-int migrate_prep(void)
+void migrate_prep(void)
 {
 	/*
 	 * Clear the LRU lists so pages can be isolated.
@@ -71,16 +71,12 @@ int migrate_prep(void)
 	 * pages that may be busy.
 	 */
 	lru_add_drain_all();
-
-	return 0;
 }
 
 /* Do the necessary work of migrate_prep but not if it involves other CPUs */
-int migrate_prep_local(void)
+void migrate_prep_local(void)
 {
 	lru_add_drain();
-
-	return 0;
 }
 
 int isolate_movable_page(struct page *page, isolate_mode_t mode)
-- 
2.26.2