On 06/02/2025 10:55, Anshuman Khandual wrote:

On 2/5/25 20:39, Ryan Roberts wrote:

quoted

Convert page_table_check_p[mu]d_set(...) to
page_table_check_p[mu]ds_set(..., nr) to allow checking a contiguous set
of pmds/puds in single batch. We retain page_table_check_p[mu]d_set(...)
as macros that call new batch functions with nr=1 for compatibility.

arm64 is about to reorganise its pte/pmd/pud helpers to reuse more code
and to allow the implementation for huge_pte to more efficiently set
ptes/pmds/puds in batches. We need these batch-helpers to make the
refactoring possible.

A very small nit.

Although this justification here is reasonable enough but not sure if
platform specific requirements, need to be spelled out in such detail
for a generic MM change.

Personally I find the "why" to be the most useful part of a commit log. I'd
prefer to leave it in unless any mm people complain.

quoted

Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---

Regardless, LGTM.

Reviewed-by: Anshuman Khandual <redacted>

Thanks!

quoted

 include/linux/page_table_check.h | 30 +++++++++++++++++-----------
 mm/page_table_check.c            | 34 +++++++++++++++++++-------------
 2 files changed, 38 insertions(+), 26 deletions(-)

diff --git a/include/linux/page_table_check.h b/include/linux/page_table_check.h
index 6722941c7cb8..289620d4aad3 100644
--- a/include/linux/page_table_check.h
+++ b/include/linux/page_table_check.h

@@ -19,8 +19,10 @@ void __page_table_check_pmd_clear(struct mm_struct *mm, pmd_t pmd);
 void __page_table_check_pud_clear(struct mm_struct *mm, pud_t pud);
 void __page_table_check_ptes_set(struct mm_struct *mm, pte_t *ptep, pte_t pte,
 		unsigned int nr);
-void __page_table_check_pmd_set(struct mm_struct *mm, pmd_t *pmdp, pmd_t pmd);
-void __page_table_check_pud_set(struct mm_struct *mm, pud_t *pudp, pud_t pud);
+void __page_table_check_pmds_set(struct mm_struct *mm, pmd_t *pmdp, pmd_t pmd,
+		unsigned int nr);
+void __page_table_check_puds_set(struct mm_struct *mm, pud_t *pudp, pud_t pud,
+		unsigned int nr);
 void __page_table_check_pte_clear_range(struct mm_struct *mm,
 					unsigned long addr,
 					pmd_t pmd);

@@ -74,22 +76,22 @@ static inline void page_table_check_ptes_set(struct mm_struct *mm,
 	__page_table_check_ptes_set(mm, ptep, pte, nr);
 }
 
-static inline void page_table_check_pmd_set(struct mm_struct *mm, pmd_t *pmdp,
-					    pmd_t pmd)
+static inline void page_table_check_pmds_set(struct mm_struct *mm,
+		pmd_t *pmdp, pmd_t pmd, unsigned int nr)
 {
 	if (static_branch_likely(&page_table_check_disabled))
 		return;
 
-	__page_table_check_pmd_set(mm, pmdp, pmd);
+	__page_table_check_pmds_set(mm, pmdp, pmd, nr);
 }
 
-static inline void page_table_check_pud_set(struct mm_struct *mm, pud_t *pudp,
-					    pud_t pud)
+static inline void page_table_check_puds_set(struct mm_struct *mm,
+		pud_t *pudp, pud_t pud, unsigned int nr)
 {
 	if (static_branch_likely(&page_table_check_disabled))
 		return;
 
-	__page_table_check_pud_set(mm, pudp, pud);
+	__page_table_check_puds_set(mm, pudp, pud, nr);
 }
 
 static inline void page_table_check_pte_clear_range(struct mm_struct *mm,

@@ -129,13 +131,13 @@ static inline void page_table_check_ptes_set(struct mm_struct *mm,
 {
 }
 
-static inline void page_table_check_pmd_set(struct mm_struct *mm, pmd_t *pmdp,
-					    pmd_t pmd)
+static inline void page_table_check_pmds_set(struct mm_struct *mm,
+		pmd_t *pmdp, pmd_t pmd, unsigned int nr)
 {
 }
 
-static inline void page_table_check_pud_set(struct mm_struct *mm, pud_t *pudp,
-					    pud_t pud)
+static inline void page_table_check_puds_set(struct mm_struct *mm,
+		pud_t *pudp, pud_t pud, unsigned int nr)
 {
 }
 

@@ -146,4 +148,8 @@ static inline void page_table_check_pte_clear_range(struct mm_struct *mm,
 }
 
 #endif /* CONFIG_PAGE_TABLE_CHECK */
+
+#define page_table_check_pmd_set(mm, pmdp, pmd)	page_table_check_pmds_set(mm, pmdp, pmd, 1)
+#define page_table_check_pud_set(mm, pudp, pud)	page_table_check_puds_set(mm, pudp, pud, 1)
+
 #endif /* __LINUX_PAGE_TABLE_CHECK_H */

diff --git a/mm/page_table_check.c b/mm/page_table_check.c
index 509c6ef8de40..dae4a7d776b3 100644
--- a/mm/page_table_check.c
+++ b/mm/page_table_check.c

@@ -234,33 +234,39 @@ static inline void page_table_check_pmd_flags(pmd_t pmd)
 		WARN_ON_ONCE(swap_cached_writable(pmd_to_swp_entry(pmd)));
 }
 
-void __page_table_check_pmd_set(struct mm_struct *mm, pmd_t *pmdp, pmd_t pmd)
+void __page_table_check_pmds_set(struct mm_struct *mm, pmd_t *pmdp, pmd_t pmd,
+		unsigned int nr)
 {
+	unsigned int i;
+	unsigned long stride = PMD_SIZE >> PAGE_SHIFT;
+
 	if (&init_mm == mm)
 		return;
 
 	page_table_check_pmd_flags(pmd);
 
-	__page_table_check_pmd_clear(mm, *pmdp);
-	if (pmd_user_accessible_page(pmd)) {
-		page_table_check_set(pmd_pfn(pmd), PMD_SIZE >> PAGE_SHIFT,
-				     pmd_write(pmd));
-	}
+	for (i = 0; i < nr; i++)
+		__page_table_check_pmd_clear(mm, *(pmdp + i));
+	if (pmd_user_accessible_page(pmd))
+		page_table_check_set(pmd_pfn(pmd), stride * nr, pmd_write(pmd));
 }
-EXPORT_SYMBOL(__page_table_check_pmd_set);
+EXPORT_SYMBOL(__page_table_check_pmds_set);
 
-void __page_table_check_pud_set(struct mm_struct *mm, pud_t *pudp, pud_t pud)
+void __page_table_check_puds_set(struct mm_struct *mm, pud_t *pudp, pud_t pud,
+		unsigned int nr)
 {
+	unsigned int i;
+	unsigned long stride = PUD_SIZE >> PAGE_SHIFT;
+
 	if (&init_mm == mm)
 		return;
 
-	__page_table_check_pud_clear(mm, *pudp);
-	if (pud_user_accessible_page(pud)) {
-		page_table_check_set(pud_pfn(pud), PUD_SIZE >> PAGE_SHIFT,
-				     pud_write(pud));
-	}
+	for (i = 0; i < nr; i++)
+		__page_table_check_pud_clear(mm, *(pudp + i));
+	if (pud_user_accessible_page(pud))
+		page_table_check_set(pud_pfn(pud), stride * nr, pud_write(pud));
 }
-EXPORT_SYMBOL(__page_table_check_pud_set);
+EXPORT_SYMBOL(__page_table_check_puds_set);
 
 void __page_table_check_pte_clear_range(struct mm_struct *mm,
 					unsigned long addr,