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| author | Hugh Dickins <hugh.dickins@tiscali.co.uk> | 2009-12-14 17:58:57 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-15 08:53:17 -0800 |
| commit | 3ca7b3c5b64d35fe02c35b5d44c2c58b49499fee (patch) | |
| tree | bb6af24d3683788ef658282f8794af19d2232663 /include/linux/ksm.h | |
| parent | bb3ab596832b920c703d1aea1ce76d69c0f71fb7 (diff) | |
| download | linux-3ca7b3c5b64d35fe02c35b5d44c2c58b49499fee.tar.gz linux-3ca7b3c5b64d35fe02c35b5d44c2c58b49499fee.tar.bz2 linux-3ca7b3c5b64d35fe02c35b5d44c2c58b49499fee.zip | |
mm: define PAGE_MAPPING_FLAGS
At present we define PageAnon(page) by the low PAGE_MAPPING_ANON bit set
in page->mapping, with the higher bits a pointer to the anon_vma; and have
defined PageKsm(page) as that with NULL anon_vma.
But KSM swapping will need to store a pointer there: so in preparation for
that, now define PAGE_MAPPING_FLAGS as the low two bits, including
PAGE_MAPPING_KSM (always set along with PAGE_MAPPING_ANON, until some
other use for the bit emerges).
Declare page_rmapping(page) to return the pointer part of page->mapping,
and page_anon_vma(page) to return the anon_vma pointer when that's what it
is. Use these in a few appropriate places: notably, unuse_vma() has been
testing page->mapping, but is better to be testing page_anon_vma() (cases
may be added in which flag bits are set without any pointer).
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
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 | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/include/linux/ksm.h b/include/linux/ksm.h index a485c14ecd5d..1401a313fa77 100644 --- a/include/linux/ksm.h +++ b/include/linux/ksm.h @@ -38,7 +38,8 @@ static inline void ksm_exit(struct mm_struct *mm) */ static inline int PageKsm(struct page *page) { - return ((unsigned long)page->mapping == PAGE_MAPPING_ANON); + return ((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) == + (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM); } /* @@ -47,7 +48,7 @@ static inline int PageKsm(struct page *page) static inline void page_add_ksm_rmap(struct page *page) { if (atomic_inc_and_test(&page->_mapcount)) { - page->mapping = (void *) PAGE_MAPPING_ANON; + page->mapping = (void *) (PAGE_MAPPING_ANON | PAGE_MAPPING_KSM); __inc_zone_page_state(page, NR_ANON_PAGES); } } |