diff options
| author |   Hugh Dickins <hugh.dickins@tiscali.co.uk> | 2009-09-21 17:02:01 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-22 07:17:31 -0700 |
| commit | 9a840895147b12de5cdd633c600b38686840ee53 (patch) | |
| tree | a266a69a39decb4ec0364ac331f0ab19b6f09f06 /include/linux/ksm.h | |
| parent | ksm: no debug in page_dup_rmap() (diff) | |
| download | linux-dev-9a840895147b12de5cdd633c600b38686840ee53.tar.xz linux-dev-9a840895147b12de5cdd633c600b38686840ee53.zip | |
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/linux/ksm.h')
| -rw-r--r-- | include/linux/ksm.h | 29 |
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 @@ #include <linux/bitops.h> #include <linux/mm.h> #include <linux/sched.h> +#include <linux/vmstat.h> #ifdef CONFIG_KSM int ksm_madvise(struct vm_area_struct *vma, unsigned long start, @@ -29,6 +30,27 @@ static inline void ksm_exit(struct mm_struct *mm) if (test_bit(MMF_VM_MERGEABLE, &mm->flags)) __ksm_exit(mm); } + +/* + * A KSM page is one of those write-protected "shared pages" or "merged pages" + * which KSM maps into multiple mms, wherever identical anonymous page content + * is found in VM_MERGEABLE vmas. It's a PageAnon page, with NULL anon_vma. + */ +static inline int PageKsm(struct page *page) +{ + return ((unsigned long)page->mapping == PAGE_MAPPING_ANON); +} + +/* + * But we have to avoid the checking which page_add_anon_rmap() performs. + */ +static inline void page_add_ksm_rmap(struct page *page) +{ + if (atomic_inc_and_test(&page->_mapcount)) { + page->mapping = (void *) PAGE_MAPPING_ANON; + __inc_zone_page_state(page, NR_ANON_PAGES); + } +} #else /* !CONFIG_KSM */ static 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) static inline void ksm_exit(struct mm_struct *mm) { } + +static inline int PageKsm(struct page *page) +{ + return 0; +} + +/* No stub required for page_add_ksm_rmap(page) */ #endif /* !CONFIG_KSM */ #endif |