linux-kernel - [PATCH v1] mm: use ptep_get() instead of directly dereferencing pte

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Message-ID: <20250310140418.1737409-1-ryan.roberts@arm.com>
Date: Mon, 10 Mar 2025 14:04:17 +0000
From: Ryan Roberts <ryan.roberts@....com>
To: Andrew Morton <akpm@...ux-foundation.org>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Ryan Roberts <ryan.roberts@....com>,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v1] mm: use ptep_get() instead of directly dereferencing pte_t*

It is best practice for all pte accesses to go via the arch helpers, to
ensure non-torn values and to allow the arch to intervene where needed
(contpte for arm64 for example). While in this case it was probably safe
to directly dereference, let's tidy it up for consistency.

Signed-off-by: Ryan Roberts <ryan.roberts@....com>
---
 mm/migrate.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 22e270f727ed..33a22c2d6b20 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -202,7 +202,7 @@ static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw,
 		return false;
 	VM_BUG_ON_PAGE(!PageAnon(page), page);
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
-	VM_BUG_ON_PAGE(pte_present(*pvmw->pte), page);
+	VM_BUG_ON_PAGE(pte_present(ptep_get(pvmw->pte)), page);

 	if (folio_test_mlocked(folio) || (pvmw->vma->vm_flags & VM_LOCKED) ||
 	    mm_forbids_zeropage(pvmw->vma->vm_mm))
--
2.43.0