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author | Hugh Dickins <hugh.dickins@tiscali.co.uk> | 2009-12-15 04:58:57 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-12-15 19:53:17 +0300 |
commit | 3ca7b3c5b64d35fe02c35b5d44c2c58b49499fee (patch) | |
tree | bb6af24d3683788ef658282f8794af19d2232663 /include/linux/rmap.h | |
parent | bb3ab596832b920c703d1aea1ce76d69c0f71fb7 (diff) | |
download | linux-3ca7b3c5b64d35fe02c35b5d44c2c58b49499fee.tar.xz |
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/rmap.h')
-rw-r--r-- | include/linux/rmap.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/rmap.h b/include/linux/rmap.h index cb0ba7032609..1f65af44c6d2 100644 --- a/include/linux/rmap.h +++ b/include/linux/rmap.h @@ -39,6 +39,14 @@ struct anon_vma { #ifdef CONFIG_MMU +static inline struct anon_vma *page_anon_vma(struct page *page) +{ + if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) != + PAGE_MAPPING_ANON) + return NULL; + return page_rmapping(page); +} + static inline void anon_vma_lock(struct vm_area_struct *vma) { struct anon_vma *anon_vma = vma->anon_vma; |