Doug / smarc-fsl-linux-kernel

Download as
Browse Code ยป

Commit 83813267c699ab11cc65a6d9d0f42db42f0862b3

Authored by Peter Zijlstra
Committed by Linus Torvalds
1 parent 9e60109f12
Exists in master and in 7 other branches imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-l5.0.0_1.0.0-ga

mm: move anon_vma ref out from under CONFIG_foo 

We need the anon_vma refcount unconditionally to simplify the anon_vma
lifetime rules.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 2 changed files with 10 additions and 44 deletions Side-by-side Diff

include/linux/rmap.h
Diff comments   View file @ 8381326
... ... @@ -27,18 +27,15 @@
27 27 struct anon_vma {
28 28 struct anon_vma *root; /* Root of this anon_vma tree */
29 29 spinlock_t lock; /* Serialize access to vma list */
30   -#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
31   -
32 30 /*
33   - * The external_refcount is taken by either KSM or page migration
34   - * to take a reference to an anon_vma when there is no
  31 + * The refcount is taken on an anon_vma when there is no
35 32 * guarantee that the vma of page tables will exist for
36 33 * the duration of the operation. A caller that takes
37 34 * the reference is responsible for clearing up the
38 35 * anon_vma if they are the last user on release
39 36 */
40   - atomic_t external_refcount;
41   -#endif
  37 + atomic_t refcount;
  38 +
42 39 /*
43 40 * NOTE: the LSB of the head.next is set by
44 41 * mm_take_all_locks() _after_ taking the above lock. So the
45 42  
46 43  
... ... @@ -71,41 +68,12 @@
71 68 };
72 69  
73 70 #ifdef CONFIG_MMU
74   -#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
75   -static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
76   -{
77   - atomic_set(&anon_vma->external_refcount, 0);
78   -}
79   -
80   -static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
81   -{
82   - return atomic_read(&anon_vma->external_refcount);
83   -}
84   -
85 71 static inline void get_anon_vma(struct anon_vma *anon_vma)
86 72 {
87   - atomic_inc(&anon_vma->external_refcount);
  73 + atomic_inc(&anon_vma->refcount);
88 74 }
89 75  
90 76 void put_anon_vma(struct anon_vma *);
91   -#else
92   -static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
93   -{
94   -}
95   -
96   -static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
97   -{
98   - return 0;
99   -}
100   -
101   -static inline void get_anon_vma(struct anon_vma *anon_vma)
102   -{
103   -}
104   -
105   -static inline void put_anon_vma(struct anon_vma *anon_vma)
106   -{
107   -}
108   -#endif /* CONFIG_KSM */
109 77  
110 78 static inline struct anon_vma *page_anon_vma(struct page *page)
111 79 {
... ... @@ -272,7 +272,7 @@
272 272 list_del(&anon_vma_chain->same_anon_vma);
273 273  
274 274 /* We must garbage collect the anon_vma if it's empty */
275   - empty = list_empty(&anon_vma->head) && !anonvma_external_refcount(anon_vma);
  275 + empty = list_empty(&anon_vma->head) && !atomic_read(&anon_vma->refcount);
276 276 anon_vma_unlock(anon_vma);
277 277  
278 278 if (empty) {
... ... @@ -303,7 +303,7 @@
303 303 struct anon_vma *anon_vma = data;
304 304  
305 305 spin_lock_init(&anon_vma->lock);
306   - anonvma_external_refcount_init(anon_vma);
  306 + atomic_set(&anon_vma->refcount, 0);
307 307 INIT_LIST_HEAD(&anon_vma->head);
308 308 }
309 309  
... ... @@ -1486,7 +1486,6 @@
1486 1486 return try_to_unmap_file(page, TTU_MUNLOCK);
1487 1487 }
1488 1488  
1489   -#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
1490 1489 /*
1491 1490 * Drop an anon_vma refcount, freeing the anon_vma and anon_vma->root
1492 1491 * if necessary. Be careful to do all the tests under the lock. Once
... ... @@ -1495,8 +1494,8 @@
1495 1494 */
1496 1495 void put_anon_vma(struct anon_vma *anon_vma)
1497 1496 {
1498   - BUG_ON(atomic_read(&anon_vma->external_refcount) <= 0);
1499   - if (atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->root->lock)) {
  1497 + BUG_ON(atomic_read(&anon_vma->refcount) <= 0);
  1498 + if (atomic_dec_and_lock(&anon_vma->refcount, &anon_vma->root->lock)) {
1500 1499 struct anon_vma *root = anon_vma->root;
1501 1500 int empty = list_empty(&anon_vma->head);
1502 1501 int last_root_user = 0;
... ... @@ -1507,8 +1506,8 @@
1507 1506 * the refcount on the root and check if we need to free it.
1508 1507 */
1509 1508 if (empty && anon_vma != root) {
1510   - BUG_ON(atomic_read(&root->external_refcount) <= 0);
1511   - last_root_user = atomic_dec_and_test(&root->external_refcount);
  1509 + BUG_ON(atomic_read(&root->refcount) <= 0);
  1510 + last_root_user = atomic_dec_and_test(&root->refcount);
1512 1511 root_empty = list_empty(&root->head);
1513 1512 }
1514 1513 anon_vma_unlock(anon_vma);
... ... @@ -1520,7 +1519,6 @@
1520 1519 }
1521 1520 }
1522 1521 }
1523   -#endif
1524 1522  
1525 1523 #ifdef CONFIG_MIGRATION
1526 1524 /*