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authorHugh Dickins <hugh.dickins@tiscali.co.uk>2009-09-21 20:02:01 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2009-09-22 10:17:31 -0400
commit9a840895147b12de5cdd633c600b38686840ee53 (patch)
treea266a69a39decb4ec0364ac331f0ab19b6f09f06 /include
parent21333b2b66b805a360641568588e5a0bb06d9d1f (diff)
ksm: identify PageKsm pages
KSM will need to identify its kernel merged pages unambiguously, and /proc/kpageflags will probably like to do so too. Since KSM will only be substituting anonymous pages, statistics are best preserved by making a PageKsm page a special PageAnon page: one with no anon_vma. But KSM then needs its own page_add_ksm_rmap() - keep it in ksm.h near PageKsm; and do_wp_page() must COW them, unlike singly mapped PageAnons. Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk> Signed-off-by: Chris Wright <chrisw@redhat.com> Signed-off-by: Izik Eidus <ieidus@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Avi Kivity <avi@redhat.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> 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/ksm.h29
1 files changed, 29 insertions, 0 deletions
diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index eb2a448981ee..a485c14ecd5d 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -10,6 +10,7 @@
10#include <linux/bitops.h> 10#include <linux/bitops.h>
11#include <linux/mm.h> 11#include <linux/mm.h>
12#include <linux/sched.h> 12#include <linux/sched.h>
13#include <linux/vmstat.h>
13 14
14#ifdef CONFIG_KSM 15#ifdef CONFIG_KSM
15int ksm_madvise(struct vm_area_struct *vma, unsigned long start, 16int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
@@ -29,6 +30,27 @@ static inline void ksm_exit(struct mm_struct *mm)
29 if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) 30 if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
30 __ksm_exit(mm); 31 __ksm_exit(mm);
31} 32}
33
34/*
35 * A KSM page is one of those write-protected "shared pages" or "merged pages"
36 * which KSM maps into multiple mms, wherever identical anonymous page content
37 * is found in VM_MERGEABLE vmas. It's a PageAnon page, with NULL anon_vma.
38 */
39static inline int PageKsm(struct page *page)
40{
41 return ((unsigned long)page->mapping == PAGE_MAPPING_ANON);
42}
43
44/*
45 * But we have to avoid the checking which page_add_anon_rmap() performs.
46 */
47static inline void page_add_ksm_rmap(struct page *page)
48{
49 if (atomic_inc_and_test(&page->_mapcount)) {
50 page->mapping = (void *) PAGE_MAPPING_ANON;
51 __inc_zone_page_state(page, NR_ANON_PAGES);
52 }
53}
32#else /* !CONFIG_KSM */ 54#else /* !CONFIG_KSM */
33 55
34static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start, 56static inline int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
@@ -45,6 +67,13 @@ static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
45static inline void ksm_exit(struct mm_struct *mm) 67static inline void ksm_exit(struct mm_struct *mm)
46{ 68{
47} 69}
70
71static inline int PageKsm(struct page *page)
72{
73 return 0;
74}
75
76/* No stub required for page_add_ksm_rmap(page) */
48#endif /* !CONFIG_KSM */ 77#endif /* !CONFIG_KSM */
49 78
50#endif 79#endif