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Mon, 10 Mar 2025 07:04:33 -0700 (PDT) From: Ryan Roberts To: Andrew Morton , Lorenzo Stoakes Cc: Ryan Roberts , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v1] mm: use ptep_get() instead of directly dereferencing pte_t* Date: Mon, 10 Mar 2025 14:04:17 +0000 Message-ID: <20250310140418.1737409-1-ryan.roberts@arm.com> X-Mailer: git-send-email 2.43.0 MIME-Version: 1.0 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 702851C0019 X-Stat-Signature: pzm9dkrza6ffo4kpb91sy8prgbxsgih9 X-Rspam-User: X-HE-Tag: 1741615475-627958 X-HE-Meta: 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 6QLGg5SF +3XG22pD6+uhrioIl41HUfiWLUN8ledKfNVHcTUYy1s2dsKhZLctG5HIFFsTSZG+CcrV2K8Nh70Z+ItSy/nec5GLeYu0h+1A6F1E8nKD1v9UyoNBm954mY1Y13f08ohkfJdNeUvq8J/o7pNedEwjZfyQFdmemOkMEFRJz6B9938ymXgEs+e1vRSOOY+l6L/u7xR7i X-Bogosity: Ham, tests=bogofilter, spamicity=0.000005, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 Reviewed-by: Lorenzo Stoakes Reviewed-by: Qi Zheng Reviewed-by: Anshuman Khandual Reviewed-by: Dev Jain --- mm/migrate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 2.43.0 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))