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mm: differentiate page_mapped() from page_mapcount() for compound pages

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Let's define page_mapped() to be true for compound pages if any
sub-pages of the compound page is mapped (with PMD or PTE).

On other hand page_mapcount() return mapcount for this particular small
page.

This will make cases like page_get_anon_vma() behave correctly once we
allow huge pages to be mapped with PTE.

Most users outside core-mm should use page_mapcount() instead of
page_mapped().

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Tested-by: Sasha Levin <sasha.levin@oracle.com>
Tested-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov
2016-01-15 16:53:46 -08:00
committed by Linus Torvalds
parent 53f9263bab
commit e1534ae950
11 changed files with 31 additions and 19 deletions
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15
include/linux/mm.h
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@@ -953,10 +953,21 @@ static inline pgoff_t page_file_index(struct page *page)
/*
* Return true if this page is mapped into pagetables.
* For compound page it returns true if any subpage of compound page is mapped.
*/
static inline int page_mapped(struct page *page)
static inline bool page_mapped(struct page *page)
{
return atomic_read(&(page)->_mapcount) + compound_mapcount(page) >= 0;
int i;
if (likely(!PageCompound(page)))
return atomic_read(&page->_mapcount) >= 0;
page = compound_head(page);
if (atomic_read(compound_mapcount_ptr(page)) >= 0)
return true;
for (i = 0; i < hpage_nr_pages(page); i++) {
if (atomic_read(&page[i]._mapcount) >= 0)
return true;
}
return false;
}
/*