On Wed, Nov 04, 2015 at 05:20:15PM +0800, Hillf Danton wrote:
> > @@ -1135,20 +1135,12 @@ void do_page_add_anon_rmap(struct page *page,
> > bool compound = flags & RMAP_COMPOUND;
> > bool first;
> >
> > - if (PageTransCompound(page)) {
> > + if (compound) {
> > + atomic_t *mapcount;
> > VM_BUG_ON_PAGE(!PageLocked(page), page);
> > - if (compound) {
> > - atomic_t *mapcount;
> > -
> > - VM_BUG_ON_PAGE(!PageTransHuge(page), page);
> > - mapcount = compound_mapcount_ptr(page);
> > - first = atomic_inc_and_test(mapcount);
> > - } else {
> > - /* Anon THP always mapped first with PMD */
> > - first = 0;
> > - VM_BUG_ON_PAGE(!page_mapcount(page), page);
> > - atomic_inc(&page->_mapcount);
> > - }
> > + VM_BUG_ON_PAGE(!PageTransHuge(page), page);
> > + mapcount = compound_mapcount_ptr(page);
> > + first = atomic_inc_and_test(mapcount);
> > } else {
> > VM_BUG_ON_PAGE(compound, page);
>
> Then this debug info is no longer needed.
> > first = atomic_inc_and_test(&page->_mapcount);
Right.
diff --git a/mm/rmap.c b/mm/rmap.c
index 0837487d3737..a9550b1f74cd 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1186,7 +1186,6 @@ void do_page_add_anon_rmap(struct page *page,
mapcount = compound_mapcount_ptr(page);
first = atomic_inc_and_test(mapcount);
} else {
- VM_BUG_ON_PAGE(compound, page);
first = atomic_inc_and_test(&page->_mapcount);
}
--
Kirill A. Shutemov
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