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authorMel Gorman <mel@csn.ul.ie>2010-05-24 17:32:18 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-25 11:06:58 -0400
commit7f60c214fd3a360461f3286c6908084f7f8b1950 (patch)
treedba48cf988a22a40796187c7274f7903a288f7f4 /include
parent3f6c82728f4e31a97c3a1b32abccb512fed0b573 (diff)
mm: migration: share the anon_vma ref counts between KSM and page migration
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@csn.ul.ie> Reviewed-by: Minchan Kim <minchan.kim@gmail.com> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Christoph Lameter <cl@linux-foundation.org> Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/rmap.h50
1 files changed, 18 insertions, 32 deletions
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 567d43f29a10..77216742c178 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -26,11 +26,17 @@
26 */ 26 */
27struct anon_vma { 27struct anon_vma {
28 spinlock_t lock; /* Serialize access to vma list */ 28 spinlock_t lock; /* Serialize access to vma list */
29#ifdef CONFIG_KSM 29#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
30 atomic_t ksm_refcount; 30
31#endif 31 /*
32#ifdef CONFIG_MIGRATION 32 * The external_refcount is taken by either KSM or page migration
33 atomic_t migrate_refcount; 33 * to take a reference to an anon_vma when there is no
34 * guarantee that the vma of page tables will exist for
35 * the duration of the operation. A caller that takes
36 * the reference is responsible for clearing up the
37 * anon_vma if they are the last user on release
38 */
39 atomic_t external_refcount;
34#endif 40#endif
35 /* 41 /*
36 * NOTE: the LSB of the head.next is set by 42 * NOTE: the LSB of the head.next is set by
@@ -64,46 +70,26 @@ struct anon_vma_chain {
64}; 70};
65 71
66#ifdef CONFIG_MMU 72#ifdef CONFIG_MMU
67#ifdef CONFIG_KSM 73#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
68static inline void ksm_refcount_init(struct anon_vma *anon_vma) 74static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
69{ 75{
70 atomic_set(&anon_vma->ksm_refcount, 0); 76 atomic_set(&anon_vma->external_refcount, 0);
71} 77}
72 78
73static inline int ksm_refcount(struct anon_vma *anon_vma) 79static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
74{ 80{
75 return atomic_read(&anon_vma->ksm_refcount); 81 return atomic_read(&anon_vma->external_refcount);
76} 82}
77#else 83#else
78static inline void ksm_refcount_init(struct anon_vma *anon_vma) 84static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
79{ 85{
80} 86}
81 87
82static inline int ksm_refcount(struct anon_vma *anon_vma) 88static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
83{ 89{
84 return 0; 90 return 0;
85} 91}
86#endif /* CONFIG_KSM */ 92#endif /* CONFIG_KSM */
87#ifdef CONFIG_MIGRATION
88static inline void migrate_refcount_init(struct anon_vma *anon_vma)
89{
90 atomic_set(&anon_vma->migrate_refcount, 0);
91}
92
93static inline int migrate_refcount(struct anon_vma *anon_vma)
94{
95 return atomic_read(&anon_vma->migrate_refcount);
96}
97#else
98static inline void migrate_refcount_init(struct anon_vma *anon_vma)
99{
100}
101
102static inline int migrate_refcount(struct anon_vma *anon_vma)
103{
104 return 0;
105}
106#endif /* CONFIG_MIGRATE */
107 93
108static inline struct anon_vma *page_anon_vma(struct page *page) 94static inline struct anon_vma *page_anon_vma(struct page *page)
109{ 95{