linux-kernel - [PATCH v1 04/11] mm: thp: simlify total

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

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@...hat.com>
Signed-off-by: David Hildenbrand <david@...hat.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