Let's avoid working with the PMD when not required. If
vm_normal_page_pmd() would be called on something that is not a present
pmd, it would already be a bug (pfn possibly garbage).
While at it, let's support passing in any pfn covered by the huge zero
folio by masking off PFN bits -- which should be rather cheap.
Signed-off-by: David Hildenbrand <david@redhat.com>
---
include/linux/huge_mm.h | 12 +++++++++++-
mm/memory.c | 2 +-
2 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 35e34e6a98a27..b260f9a1fd3f2 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -483,9 +483,14 @@ static inline bool is_huge_zero_folio(const struct folio *folio)
return READ_ONCE(huge_zero_folio) == folio;
}
+static inline bool is_huge_zero_pfn(unsigned long pfn)
+{
+ return READ_ONCE(huge_zero_pfn) == (pfn & ~(HPAGE_PMD_NR - 1));
+}
+
static inline bool is_huge_zero_pmd(pmd_t pmd)
{
- return pmd_present(pmd) && READ_ONCE(huge_zero_pfn) == pmd_pfn(pmd);
+ return pmd_present(pmd) && is_huge_zero_pfn(pmd_pfn(pmd));
}
struct folio *mm_get_huge_zero_folio(struct mm_struct *mm);
@@ -633,6 +638,11 @@ static inline bool is_huge_zero_folio(const struct folio *folio)
return false;
}
+static inline bool is_huge_zero_pfn(unsigned long pfn)
+{
+ return false;
+}
+
static inline bool is_huge_zero_pmd(pmd_t pmd)
{
return false;
diff --git a/mm/memory.c b/mm/memory.c
index ef277dab69e33..b6c069f4ad11f 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -669,7 +669,7 @@ struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
}
}
- if (is_huge_zero_pmd(pmd))
+ if (is_huge_zero_pfn(pfn))
return NULL;
/*
--
2.49.0