From:   David Hildenbrand <david@redhat.com>
To:     linux-kernel@vger.kernel.org
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        David Rientjes <rientjes@google.com>,
        Shakeel Butt <shakeelb@google.com>,
        John Hubbard <jhubbard@nvidia.com>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Mike Rapoport <rppt@linux.ibm.com>,
        Yang Shi <shy828301@gmail.com>,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Matthew Wilcox <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>, Jann Horn <jannh@google.com>,
        Michal Hocko <mhocko@kernel.org>,
        Nadav Amit <namit@vmware.com>, Rik van Riel <riel@surriel.com>,
        Roman Gushchin <guro@fb.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Peter Xu <peterx@redhat.com>,
        Donald Dutile <ddutile@redhat.com>,
        Christoph Hellwig <hch@lst.de>,
        Oleg Nesterov <oleg@redhat.com>, Jan Kara <jack@suse.cz>,
        linux-mm@kvack.org, linux-kselftest@vger.kernel.org,
        linux-doc@vger.kernel.org, David Hildenbrand <david@redhat.com>
Subject: [PATCH v1 04/11] mm: thp: simlify total_mapcount()
Date:   Fri, 17 Dec 2021 12:30:42 +0100
Message-Id: <20211217113049.23850-5-david@redhat.com>
In-Reply-To: <20211217113049.23850-1-david@redhat.com>
References: <20211217113049.23850-1-david@redhat.com>
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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>
---
 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