linux-kernel - [PATCH v1 09/18] mm/memory-failure: use folio_mapcount() in hwpoison_user

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Date: Tue,  9 Apr 2024 21:22:52 +0200
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
	linux-doc@...r.kernel.org,
	cgroups@...r.kernel.org,
	linux-sh@...r.kernel.org,
	linux-trace-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	David Hildenbrand <david@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	Peter Xu <peterx@...hat.com>,
	Ryan Roberts <ryan.roberts@....com>,
	Yin Fengwei <fengwei.yin@...el.com>,
	Yang Shi <shy828301@...il.com>,
	Zi Yan <ziy@...dia.com>,
	Jonathan Corbet <corbet@....net>,
	Hugh Dickins <hughd@...gle.com>,
	Yoshinori Sato <ysato@...rs.sourceforge.jp>,
	Rich Felker <dalias@...c.org>,
	John Paul Adrian Glaubitz <glaubitz@...sik.fu-berlin.de>,
	Chris Zankel <chris@...kel.net>,
	Max Filippov <jcmvbkbc@...il.com>,
	Muchun Song <muchun.song@...ux.dev>,
	Miaohe Lin <linmiaohe@...wei.com>,
	Naoya Horiguchi <naoya.horiguchi@....com>,
	Richard Chang <richardycc@...gle.com>
Subject: [PATCH v1 09/18] mm/memory-failure: use folio_mapcount() in hwpoison_user_mappings()

We want to limit the use of page_mapcount() to the places where it is
absolutely necessary. We can only unmap full folios; page_mapped(),
which we check here, is translated to folio_mapped() -- based on
folio_mapcount(). So let's print the folio mapcount instead.

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 mm/memory-failure.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 88359a185c5f..ee2f4b8905ef 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1628,8 +1628,8 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
 
 	unmap_success = !page_mapped(p);
 	if (!unmap_success)
-		pr_err("%#lx: failed to unmap page (mapcount=%d)\n",
-		       pfn, page_mapcount(p));
+		pr_err("%#lx: failed to unmap page (folio mapcount=%d)\n",
+		       pfn, folio_mapcount(page_folio(p)));
 
 	/*
 	 * try_to_unmap() might put mlocked page in lru cache, so call
-- 
2.44.0