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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 /mm/rmap.c
parentbb3ab596832b920c703d1aea1ce76d69c0f71fb7 (diff)
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 'mm/rmap.c')
-rw-r--r--mm/rmap.c7
1 files changed, 3 insertions, 4 deletions
diff --git a/mm/rmap.c b/mm/rmap.c
index 1a0ee6e634c2..f06cee48eca7 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -203,7 +203,7 @@ struct anon_vma *page_lock_anon_vma(struct page *page)
rcu_read_lock();
anon_mapping = (unsigned long) page->mapping;
- if (!(anon_mapping & PAGE_MAPPING_ANON))
+ if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
goto out;
if (!page_mapped(page))
goto out;
@@ -248,8 +248,7 @@ vma_address(struct page *page, struct vm_area_struct *vma)
unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)
{
if (PageAnon(page)) {
- if ((void *)vma->anon_vma !=
- (void *)page->mapping - PAGE_MAPPING_ANON)
+ if (vma->anon_vma != page_anon_vma(page))
return -EFAULT;
} else if (page->mapping && !(vma->vm_flags & VM_NONLINEAR)) {
if (!vma->vm_file ||
@@ -513,7 +512,7 @@ int page_referenced(struct page *page,
referenced++;
*vm_flags = 0;
- if (page_mapped(page) && page->mapping) {
+ if (page_mapped(page) && page_rmapping(page)) {
if (PageAnon(page))
referenced += page_referenced_anon(page, mem_cont,
vm_flags);

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