From 134ac2d4dcfec0c0487d57e4b78efbef8714b883 Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Thu, 11 Mar 2021 15:14:15 -0800 Subject: [PATCH] FROMLIST: mm: replace migrate_prep with lru_add_drain_all 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. Bug: 180018981 Link: https://lore.kernel.org/linux-mm/20210310161429.399432-1-minchan@kernel.org/ Signed-off-by: Minchan Kim Signed-off-by: Minchan Kim Change-Id: I1bd3fcb13993e8a7a7961ceec817ac17304364cb --- 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 63b4d114b415..8512469ff6fb 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 dba424447473..34d99d7d1a6a 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -2275,7 +2275,8 @@ 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 a4a6b030305e..dcb86c9d27ae 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -1127,7 +1127,7 @@ 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); @@ -1326,7 +1326,7 @@ 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 fd4cde426c80..d41cea28ee76 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; @@ -1719,7 +1697,7 @@ 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 ad392b9ff63f..1dca2d2a8c81 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -8519,7 +8519,7 @@ static int __alloc_contig_migrate_range(struct compact_control *cc, if (cc->alloc_contig && cc->mode == MIGRATE_ASYNC) max_tries = 1; - 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 d160a07830a7..6f8cc8462fab 100644 --- a/mm/swap.c +++ b/mm/swap.c @@ -753,6 +753,11 @@ 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.