[PATCH mm-new 1/1] mm: clean up is_guard_pte_marker()

[PATCH mm-new 1/1] mm: clean up is_guard_pte_marker()

[Lance Yang]

From: Lance Yang <lance.yang@linux.dev>

Let's simplify the implementation. The current code is redundant as it
effectively expands to:

  is_swap_pte(pte) &&
  is_pte_marker_entry(...) && // from is_pte_marker()
  is_pte_marker_entry(...)    // from is_guard_swp_entry()

While a modern compiler could likely optimize this away, let's have clean
code and not rely on it.

Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Lance Yang <lance.yang@linux.dev>
---
This patch is split from the series[1]. The cleanup can be applied
independently because is_guard_pte_marker() is no longer exposed.

The original Acked-by and Reviewed-by tags are kept as the change is
trivial enough.

[1] https://lore.kernel.org/linux-mm/20250918050431.36855-1-lance.yang@linux.dev

 mm/madvise.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 35ed4ab0d7c5..fb1c86e630b6 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -1071,8 +1071,8 @@ static bool is_valid_guard_vma(struct vm_area_struct *vma, bool allow_locked)
 
 static bool is_guard_pte_marker(pte_t ptent)
 {
-	return is_pte_marker(ptent) &&
-		is_guard_swp_entry(pte_to_swp_entry(ptent));
+	return is_swap_pte(ptent) &&
+	       is_guard_swp_entry(pte_to_swp_entry(ptent));
 }
 
 static int guard_install_pud_entry(pud_t *pud, unsigned long addr,
-- 
2.49.0

Re: [PATCH mm-new 1/1] mm: clean up is_guard_pte_marker()

[Dev Jain]

On 24/09/25 10:28 am, Lance Yang wrote:
> From: Lance Yang <lance.yang@linux.dev>
>
> Let's simplify the implementation. The current code is redundant as it
> effectively expands to:
>
>    is_swap_pte(pte) &&
>    is_pte_marker_entry(...) && // from is_pte_marker()
>    is_pte_marker_entry(...)    // from is_guard_swp_entry()
>
> While a modern compiler could likely optimize this away, let's have clean
> code and not rely on it.
>
> Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
> Reviewed-by: Zi Yan <ziy@nvidia.com>
> Acked-by: David Hildenbrand <david@redhat.com>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
> Signed-off-by: Lance Yang <lance.yang@linux.dev>
> ---

Reviewed-by: Dev Jain <dev.jain@arm.com>