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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2016-07-26 15:25:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-07-26 16:19:19 -0700
commitdd78fedde4b99b322f2dc849d467d365a82e23ca (patch)
tree5095c6e9fd2527a8636188059e35f7f45b9648a2 /mm/huge_memory.c
parent7267ec008b5cd8b3579e188b1ff238815643e372 (diff)
downloadlinux-dd78fedde4b99b322f2dc849d467d365a82e23ca.tar.bz2
rmap: support file thp
Naive approach: on mapping/unmapping the page as compound we update ->_mapcount on each 4k page. That's not efficient, but it's not obvious how we can optimize this. We can look into optimization later. PG_double_map optimization doesn't work for file pages since lifecycle of file pages is different comparing to anon pages: file page can be mapped again at any time. Link: http://lkml.kernel.org/r/1466021202-61880-11-git-send-email-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/huge_memory.c')
-rw-r--r--mm/huge_memory.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index bc5abcbe376e..90f5dd22b1c8 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -3301,18 +3301,22 @@ static void __split_huge_page(struct page *page, struct list_head *list)
int total_mapcount(struct page *page)
{
- int i, ret;
+ int i, compound, ret;
VM_BUG_ON_PAGE(PageTail(page), page);
if (likely(!PageCompound(page)))
return atomic_read(&page->_mapcount) + 1;
- ret = compound_mapcount(page);
+ compound = compound_mapcount(page);
if (PageHuge(page))
- return ret;
+ return compound;
+ ret = compound;
for (i = 0; i < HPAGE_PMD_NR; i++)
ret += atomic_read(&page[i]._mapcount) + 1;
+ /* File pages has compound_mapcount included in _mapcount */
+ if (!PageAnon(page))
+ return ret - compound * HPAGE_PMD_NR;
if (PageDoubleMap(page))
ret -= HPAGE_PMD_NR;
return ret;