hugetlb: remove unnecessary set_page_count in prep_compound_gigantic_page

In commit 7118fc2906e2 ("hugetlb: address ref count racing in
prep_compound_gigantic_page"), page_ref_freeze is used to atomically
zero the ref count of tail pages iff they are 1.  The unconditional call
to set_page_count(0) was left in the code.  This call is after
page_ref_freeze so it is really a noop.

Remove redundant and unnecessary set_page_count call.

Link: https://lkml.kernel.org/r/20211026220635.35187-1-mike.kravetz@oracle.com
Fixes: 7118fc2906e29 ("hugetlb: address ref count racing in prep_compound_gigantic_page")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Suggested-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e304326..5eab627 100644 (file)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1792,7 +1792,6 @@ static bool __prep_compound_gigantic_page(struct page *page, unsigned int order,
                } else {
                        VM_BUG_ON_PAGE(page_count(p), p);
                }
-               set_page_count(p, 0);
                set_compound_head(p, page);
        }
        atomic_set(compound_mapcount_ptr(page), -1);