Let's return early for hugetlb, which really only relies on the compound mapcount so far and does not support PageDoubleMap() yet. Use the chance to cleanup the file-THP case to make it easier to grasp. While at it, use head_compound_mapcount().
This is a preparation for further changes.
Reviewed-by: Peter Xu peterx@redhat.com Signed-off-by: David Hildenbrand david@redhat.com --- mm/util.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/mm/util.c b/mm/util.c index 741ba32a43ac..3239e75c148d 100644 --- a/mm/util.c +++ b/mm/util.c @@ -732,15 +732,18 @@ int __page_mapcount(struct page *page) { int ret;
- ret = atomic_read(&page->_mapcount) + 1; + if (PageHuge(page)) + return compound_mapcount(page); /* * For file THP page->_mapcount contains total number of mapping * of the page: no need to look into compound_mapcount. */ - if (!PageAnon(page) && !PageHuge(page)) - return ret; + if (!PageAnon(page)) + return atomic_read(&page->_mapcount) + 1; + + ret = atomic_read(&page->_mapcount) + 1; page = compound_head(page); - ret += atomic_read(compound_mapcount_ptr(page)) + 1; + ret += head_compound_mapcount(page); if (PageDoubleMap(page)) ret--; return ret;