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* [PATCH v3 1/3] mm: replace migrate_prep with lru_add_drain_all
@ 2021-03-10 16:14 Minchan Kim
  2021-03-10 16:14 ` [PATCH v3 2/3] mm: disable LRU pagevec during the migration temporarily Minchan Kim
                   ` (3 more replies)
  0 siblings, 4 replies; 21+ messages in thread
From: Minchan Kim @ 2021-03-10 16:14 UTC (permalink / raw)
  To: Andrew Morton
  Cc: linux-mm, LKML, joaodias, surenb, cgoldswo, willy, mhocko, david,
	vbabka, linux-fsdevel, Minchan Kim

Currently, migrate_prep is merely a wrapper of lru_cache_add_all.
There is not much to gain from having additional abstraction.

Use lru_add_drain_all instead of migrate_prep, which would be more
descriptive.

note: migrate_prep_local in compaction.c changed into lru_add_drain
to avoid CPU schedule cost with involving many other CPUs to keep
keep old behavior.

Signed-off-by: Minchan Kim <minchan@kernel.org>
---
 include/linux/migrate.h |  5 -----
 mm/compaction.c         |  3 ++-
 mm/mempolicy.c          |  4 ++--
 mm/migrate.c            | 24 +-----------------------
 mm/page_alloc.c         |  2 +-
 mm/swap.c               |  5 +++++
 6 files changed, 11 insertions(+), 32 deletions(-)

diff --git a/include/linux/migrate.h b/include/linux/migrate.h
index 3a389633b68f..6155d97ec76c 100644
--- a/include/linux/migrate.h
+++ b/include/linux/migrate.h
@@ -45,8 +45,6 @@ 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 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,
@@ -66,9 +64,6 @@ static inline struct page *alloc_migration_target(struct page *page,
 static inline int isolate_movable_page(struct page *page, isolate_mode_t mode)
 	{ return -EBUSY; }
 
-static inline int migrate_prep(void) { return -ENOSYS; }
-static inline int migrate_prep_local(void) { return -ENOSYS; }
-
 static inline void migrate_page_states(struct page *newpage, struct page *page)
 {
 }
diff --git a/mm/compaction.c b/mm/compaction.c
index e04f4476e68e..3be017ececc0 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2319,7 +2319,8 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
 	trace_mm_compaction_begin(start_pfn, cc->migrate_pfn,
 				cc->free_pfn, end_pfn, sync);
 
-	migrate_prep_local();
+	/* lru_add_drain_all could be expensive with involving other CPUs */
+	lru_add_drain();
 
 	while ((ret = compact_finished(cc)) == COMPACT_CONTINUE) {
 		int err;
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index ab51132547b8..fc024e97be37 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -1124,7 +1124,7 @@ int do_migrate_pages(struct mm_struct *mm, const nodemask_t *from,
 	int err = 0;
 	nodemask_t tmp;
 
-	migrate_prep();
+	lru_add_drain_all();
 
 	mmap_read_lock(mm);
 
@@ -1323,7 +1323,7 @@ static long do_mbind(unsigned long start, unsigned long len,
 
 	if (flags & (MPOL_MF_MOVE | MPOL_MF_MOVE_ALL)) {
 
-		migrate_prep();
+		lru_add_drain_all();
 	}
 	{
 		NODEMASK_SCRATCH(scratch);
diff --git a/mm/migrate.c b/mm/migrate.c
index 62b81d5257aa..45f925e10f5a 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -57,28 +57,6 @@
 
 #include "internal.h"
 
-/*
- * migrate_prep() needs to be called before we start compiling a list of pages
- * to be migrated using isolate_lru_page(). If scheduling work on other CPUs is
- * undesirable, use migrate_prep_local()
- */
-void migrate_prep(void)
-{
-	/*
-	 * Clear the LRU lists so pages can be isolated.
-	 * Note that pages may be moved off the LRU after we have
-	 * drained them. Those pages will fail to migrate like other
-	 * pages that may be busy.
-	 */
-	lru_add_drain_all();
-}
-
-/* Do the necessary work of migrate_prep but not if it involves other CPUs */
-void migrate_prep_local(void)
-{
-	lru_add_drain();
-}
-
 int isolate_movable_page(struct page *page, isolate_mode_t mode)
 {
 	struct address_space *mapping;
@@ -1769,7 +1747,7 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
 	int start, i;
 	int err = 0, err1;
 
-	migrate_prep();
+	lru_add_drain_all();
 
 	for (i = start = 0; i < nr_pages; i++) {
 		const void __user *p;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 2e8348936df8..f05a8db741ca 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -8467,7 +8467,7 @@ static int __alloc_contig_migrate_range(struct compact_control *cc,
 		.gfp_mask = GFP_USER | __GFP_MOVABLE | __GFP_RETRY_MAYFAIL,
 	};
 
-	migrate_prep();
+	lru_add_drain_all();
 
 	while (pfn < end || !list_empty(&cc->migratepages)) {
 		if (fatal_signal_pending(current)) {
diff --git a/mm/swap.c b/mm/swap.c
index 31b844d4ed94..441d1ae1f285 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -729,6 +729,11 @@ static void lru_add_drain_per_cpu(struct work_struct *dummy)
 }
 
 /*
+ * lru_add_drain_all() usually needs to be called before we start compiling
+ * a list of pages to be migrated using isolate_lru_page(). Note that pages
+ * may be moved off the LRU after we have drained them. Those pages will
+ * fail to migrate like other pages that may be busy.
+ *
  * Doesn't need any cpu hotplug locking because we do rely on per-cpu
  * kworkers being shut down before our page_alloc_cpu_dead callback is
  * executed on the offlined cpu.
-- 
2.30.1.766.gb4fecdf3b7-goog


^ permalink raw reply related	[flat|nested] 21+ messages in thread

end of thread, other threads:[~2021-03-19 16:48 UTC | newest]

Thread overview: 21+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-03-10 16:14 [PATCH v3 1/3] mm: replace migrate_prep with lru_add_drain_all Minchan Kim
2021-03-10 16:14 ` [PATCH v3 2/3] mm: disable LRU pagevec during the migration temporarily Minchan Kim
2021-03-11 22:41   ` Chris Goldsworthy
2021-03-14  5:10     ` Chris Goldsworthy
2021-03-12  8:21   ` Michal Hocko
2021-03-12  9:00   ` David Hildenbrand
2021-03-18  0:13   ` Andrew Morton
2021-03-18  1:13     ` Minchan Kim
2021-03-18  8:09     ` Michal Hocko
2021-03-10 16:14 ` [PATCH v3 3/3] mm: fs: Invalidate BH LRU during page migration Minchan Kim
2021-03-12  9:03   ` David Hildenbrand
2021-03-12  9:33     ` David Hildenbrand
2021-03-12 17:17       ` Minchan Kim
2021-03-16 18:26         ` Minchan Kim
2021-03-17 11:18           ` David Hildenbrand
2021-03-17  2:37   ` [mm] 8fd8d23ab1: WARNING:at_fs/buffer.c:#__brelse kernel test robot
2021-03-17 16:29     ` Minchan Kim
2021-03-19 14:05       ` Oliver Sang
2021-03-19 16:47         ` Minchan Kim
2021-03-12  8:19 ` [PATCH v3 1/3] mm: replace migrate_prep with lru_add_drain_all Michal Hocko
2021-03-12  8:53 ` David Hildenbrand

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