linux-kernel - [PATCH v1 12/18] sh/mm/cache: use folio_mapped() in copy_from_user

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Date: Tue,  9 Apr 2024 21:22:55 +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 12/18] sh/mm/cache: use folio_mapped() in copy_from_user_page()

We want to limit the use of page_mapcount() to the places where it is
absolutely necessary.

We're already using folio_mapped in copy_user_highpage() and
copy_to_user_page() for a similar purpose so ... let's also simply use
it for copy_from_user_page().

There is no change for small folios. Likely we won't stumble over many
large folios on sh in that code either way.

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 arch/sh/mm/cache.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/sh/mm/cache.c b/arch/sh/mm/cache.c
index 9bcaa5619eab..d8be352e14d2 100644
--- a/arch/sh/mm/cache.c
+++ b/arch/sh/mm/cache.c
@@ -84,7 +84,7 @@ void copy_from_user_page(struct vm_area_struct *vma, struct page *page,
 {
 	struct folio *folio = page_folio(page);
 
-	if (boot_cpu_data.dcache.n_aliases && page_mapcount(page) &&
+	if (boot_cpu_data.dcache.n_aliases && folio_mapped(folio) &&
 	    test_bit(PG_dcache_clean, &folio->flags)) {
 		void *vfrom = kmap_coherent(page, vaddr) + (vaddr & ~PAGE_MASK);
 		memcpy(dst, vfrom, len);
-- 
2.44.0