Re: [PATCH v1 04/11] mm: thp: simlify total_mapcount()

On Fri, Dec 17, 2021 at 3:33 AM David Hildenbrand david@redhat.com wrote:

Let's simplify a bit, returning for PageHuge() early and using head_compound_page() as we are only getting called for HEAD pages.

Note the VM_BUG_ON_PAGE(PageTail(page), page) check at the beginning of total_mapcount().

This is a preparation for further changes.

Reviewed-by: Peter Xu peterx@redhat.com Signed-off-by: David Hildenbrand david@redhat.com

Reviewed-by: Yang Shi shy828301@gmail.com

---

mm/huge_memory.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 4751d03947da..826cabcad11a 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2506,12 +2506,11 @@ int total_mapcount(struct page *page)

    if (likely(!PageCompound(page)))
            return atomic_read(&page->_mapcount) + 1;

•   if (PageHuge(page))
  

•           return head_compound_mapcount(page);
  
  

•   compound = compound_mapcount(page);
    nr = compound_nr(page);
  

•   if (PageHuge(page))
  

•           return compound;
  

•   ret = compound;
  

•   ret = compound = head_compound_mapcount(page);
    for (i = 0; i < nr; i++)
            ret += atomic_read(&page[i]._mapcount) + 1;
    /* File pages has compound_mapcount included in _mapcount */
  

-- 2.31.1