+ mm-use-ptep_get-instead-of-directly-dereferencing-pte_t.patch added to mm-unstable branch

+ mm-use-ptep_get-instead-of-directly-dereferencing-pte_t.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm: use ptep_get() instead of directly dereferencing pte_t*
has been added to the -mm mm-unstable branch.  Its filename is
     mm-use-ptep_get-instead-of-directly-dereferencing-pte_t.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-use-ptep_get-instead-of-directly-dereferencing-pte_t.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Ryan Roberts <ryan.roberts@arm.com>
Subject: mm: use ptep_get() instead of directly dereferencing pte_t*
Date: Mon, 10 Mar 2025 14:04:17 +0000

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.

Link: https://lkml.kernel.org/r/20250310140418.1737409-1-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Qi Zheng <zhengqi.arch@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/migrate.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/migrate.c~mm-use-ptep_get-instead-of-directly-dereferencing-pte_t
+++ a/mm/migrate.c
@@ -202,7 +202,7 @@ static bool try_to_map_unused_to_zeropag
 		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))
_

Patches currently in -mm which might be from ryan.roberts@arm.com are

mm-ioremap-pass-pgprot_t-to-ioremap_prot-instead-of-unsigned-long.patch
mm-fix-lazy-mmu-docs-and-usage.patch
fs-proc-task_mmu-reduce-scope-of-lazy-mmu-region.patch
sparc-mm-disable-preemption-in-lazy-mmu-mode.patch
sparc-mm-avoid-calling-arch_enter-leave_lazy_mmu-in-set_ptes.patch
revert-x86-xen-allow-nesting-of-same-lazy-mode.patch
mm-use-ptep_get-instead-of-directly-dereferencing-pte_t.patch