The patch titled mm: migration: share the anon_vma ref counts between KSM and page migration has been added to the -mm tree. Its filename is mmmigration-share-the-anon_vma-ref-counts-between-ksm-and-page-migration.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: mm: migration: share the anon_vma ref counts between KSM and page migration From: Mel Gorman <mel@xxxxxxxxx> For clarity of review, KSM and page migration have separate refcounts on the anon_vma. While clear, this is a waste of memory. This patch gets KSM and page migration to share their toys in a spirit of harmony. Signed-off-by: Mel Gorman <mel@xxxxxxxxx> Reviewed-by: Minchan Kim <minchan.kim@xxxxxxxxx> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Reviewed-by: Christoph Lameter <cl@xxxxxxxxxxxxxxxxxxxx> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/rmap.h | 50 ++++++++++++++--------------------------- mm/ksm.c | 4 +-- mm/migrate.c | 4 +-- mm/rmap.c | 6 +--- 4 files changed, 24 insertions(+), 40 deletions(-) diff -puN include/linux/rmap.h~mmmigration-share-the-anon_vma-ref-counts-between-ksm-and-page-migration include/linux/rmap.h --- a/include/linux/rmap.h~mmmigration-share-the-anon_vma-ref-counts-between-ksm-and-page-migration +++ a/include/linux/rmap.h @@ -26,11 +26,17 @@ */ struct anon_vma { spinlock_t lock; /* Serialize access to vma list */ -#ifdef CONFIG_KSM - atomic_t ksm_refcount; -#endif -#ifdef CONFIG_MIGRATION - atomic_t migrate_refcount; +#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION) + + /* + * The external_refcount is taken by either KSM or page migration + * to take a reference to an anon_vma when there is no + * guarantee that the vma of page tables will exist for + * the duration of the operation. A caller that takes + * the reference is responsible for clearing up the + * anon_vma if they are the last user on release + */ + atomic_t external_refcount; #endif /* * NOTE: the LSB of the head.next is set by @@ -64,46 +70,26 @@ struct anon_vma_chain { }; #ifdef CONFIG_MMU -#ifdef CONFIG_KSM -static inline void ksm_refcount_init(struct anon_vma *anon_vma) +#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION) +static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma) { - atomic_set(&anon_vma->ksm_refcount, 0); + atomic_set(&anon_vma->external_refcount, 0); } -static inline int ksm_refcount(struct anon_vma *anon_vma) +static inline int anonvma_external_refcount(struct anon_vma *anon_vma) { - return atomic_read(&anon_vma->ksm_refcount); + return atomic_read(&anon_vma->external_refcount); } #else -static inline void ksm_refcount_init(struct anon_vma *anon_vma) +static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma) { } -static inline int ksm_refcount(struct anon_vma *anon_vma) +static inline int anonvma_external_refcount(struct anon_vma *anon_vma) { return 0; } #endif /* CONFIG_KSM */ -#ifdef CONFIG_MIGRATION -static inline void migrate_refcount_init(struct anon_vma *anon_vma) -{ - atomic_set(&anon_vma->migrate_refcount, 0); -} - -static inline int migrate_refcount(struct anon_vma *anon_vma) -{ - return atomic_read(&anon_vma->migrate_refcount); -} -#else -static inline void migrate_refcount_init(struct anon_vma *anon_vma) -{ -} - -static inline int migrate_refcount(struct anon_vma *anon_vma) -{ - return 0; -} -#endif /* CONFIG_MIGRATE */ static inline struct anon_vma *page_anon_vma(struct page *page) { diff -puN mm/ksm.c~mmmigration-share-the-anon_vma-ref-counts-between-ksm-and-page-migration mm/ksm.c --- a/mm/ksm.c~mmmigration-share-the-anon_vma-ref-counts-between-ksm-and-page-migration +++ a/mm/ksm.c @@ -318,14 +318,14 @@ static void hold_anon_vma(struct rmap_it struct anon_vma *anon_vma) { rmap_item->anon_vma = anon_vma; - atomic_inc(&anon_vma->ksm_refcount); + atomic_inc(&anon_vma->external_refcount); } static void drop_anon_vma(struct rmap_item *rmap_item) { struct anon_vma *anon_vma = rmap_item->anon_vma; - if (atomic_dec_and_lock(&anon_vma->ksm_refcount, &anon_vma->lock)) { + if (atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->lock)) { int empty = list_empty(&anon_vma->head); spin_unlock(&anon_vma->lock); if (empty) diff -puN mm/migrate.c~mmmigration-share-the-anon_vma-ref-counts-between-ksm-and-page-migration mm/migrate.c --- a/mm/migrate.c~mmmigration-share-the-anon_vma-ref-counts-between-ksm-and-page-migration +++ a/mm/migrate.c @@ -601,7 +601,7 @@ static int unmap_and_move(new_page_t get rcu_read_lock(); rcu_locked = 1; anon_vma = page_anon_vma(page); - atomic_inc(&anon_vma->migrate_refcount); + atomic_inc(&anon_vma->external_refcount); } /* @@ -643,7 +643,7 @@ skip_unmap: rcu_unlock: /* Drop an anon_vma reference if we took one */ - if (anon_vma && atomic_dec_and_lock(&anon_vma->migrate_refcount, &anon_vma->lock)) { + if (anon_vma && atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->lock)) { int empty = list_empty(&anon_vma->head); spin_unlock(&anon_vma->lock); if (empty) diff -puN mm/rmap.c~mmmigration-share-the-anon_vma-ref-counts-between-ksm-and-page-migration mm/rmap.c --- a/mm/rmap.c~mmmigration-share-the-anon_vma-ref-counts-between-ksm-and-page-migration +++ a/mm/rmap.c @@ -250,8 +250,7 @@ static void anon_vma_unlink(struct anon_ list_del(&anon_vma_chain->same_anon_vma); /* We must garbage collect the anon_vma if it's empty */ - empty = list_empty(&anon_vma->head) && !ksm_refcount(anon_vma) && - !migrate_refcount(anon_vma); + empty = list_empty(&anon_vma->head) && !anonvma_external_refcount(anon_vma); spin_unlock(&anon_vma->lock); if (empty) @@ -275,8 +274,7 @@ static void anon_vma_ctor(void *data) struct anon_vma *anon_vma = data; spin_lock_init(&anon_vma->lock); - ksm_refcount_init(anon_vma); - migrate_refcount_init(anon_vma); + anonvma_external_refcount_init(anon_vma); INIT_LIST_HEAD(&anon_vma->head); } _ Patches currently in -mm which might be from mel@xxxxxxxxx are linux-next.patch hugetlb-fix-infinite-loop-in-get_futex_key-when-backed-by-huge-pages.patch hugetlb-fix-infinite-loop-in-get_futex_key-when-backed-by-huge-pages-fix.patch hugetlbfs-kill-applications-that-use-map_noreserve-with-sigbus-instead-of-oom-killer.patch page-allocator-reduce-fragmentation-in-buddy-allocator-by-adding-buddies-that-are-merging-to-the-tail-of-the-free-lists.patch mempolicy-remove-redundant-code.patch mm-default-to-node-zonelist-ordering-when-nodes-have-only-lowmem.patch mmmigration-take-a-reference-to-the-anon_vma-before-migrating.patch mmmigration-share-the-anon_vma-ref-counts-between-ksm-and-page-migration.patch mmmigration-do-not-try-to-migrate-unmapped-anonymous-pages.patch mmmigration-allow-the-migration-of-pageswapcache-pages.patch mm-allow-config_migration-to-be-set-without-config_numa-or-memory-hot-remove.patch mm-export-unusable-free-space-index-via-debugfs.patch mm-export-fragmentation-index-via-debugfs.patch mm-move-definition-for-lru-isolation-modes-to-a-header.patch mmcompaction-memory-compaction-core.patch mmcompaction-add-proc-trigger-for-memory-compaction.patch mmcompaction-add-sys-trigger-for-per-node-memory-compaction.patch mmcompaction-direct-compact-when-a-high-order-allocation-fails.patch mmcompaction-add-a-tunable-that-decides-when-memory-should-be-compacted-and-when-it-should-be-reclaimed.patch mmcompaction-defer-compaction-using-an-exponential-backoff-when-compaction-fails.patch mm-introduce-free_pages_prepare.patch mm-introduce-free_pages_prepare-fix.patch delay-accounting-re-implement-c-for-getdelaysc-to-report-information-on-a-target-command.patch delay-accounting-re-implement-c-for-getdelaysc-to-report-information-on-a-target-command-checkpatch-fixes.patch numa-add-generic-percpu-var-numa_node_id-implementation.patch numa-x86_64-use-generic-percpu-var-numa_node_id-implementation.patch numa-ia64-use-generic-percpu-var-numa_node_id-implementation.patch numa-introduce-numa_mem_id-effective-local-memory-node-id.patch numa-ia64-support-numa_mem_id-for-memoryless-nodes.patch numa-slab-use-numa_mem_id-for-slab-local-memory-node.patch numa-in-kernel-profiling-use-cpu_to_mem-for-per-cpu-allocations.patch numa-update-documentation-vm-numa-add-memoryless-node-info.patch add-debugging-aid-for-memory-initialisation-problems.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html