[v3 PATCH 4/5] mm: migrate: clean up migrate_prep{_local}

From: Yang Shi
Date: Fri Nov 13 2020 - 15:54:29 EST


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

Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Yang Shi <shy828301@xxxxxxxxx>
---
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