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authorHugh Dickins <hugh.dickins@tiscali.co.uk>2009-12-14 17:58:57 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-15 08:53:17 -0800
commit3ca7b3c5b64d35fe02c35b5d44c2c58b49499fee (patch)
treebb6af24d3683788ef658282f8794af19d2232663 /include/linux/ksm.h
parentbb3ab596832b920c703d1aea1ce76d69c0f71fb7 (diff)
downloadlinux-linaro-stable-3ca7b3c5b64d35fe02c35b5d44c2c58b49499fee.tar.gz
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.h5
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);
}
}