[PATCH V2] mm/ptdump: Replace READ_ONCE() with standard page table accessors

[PATCH V2] mm/ptdump: Replace READ_ONCE() with standard page table accessors

[Anshuman Khandual]

Replace READ_ONCE() with standard page table accessors i.e pxdp_get() which
anyways default into READ_ONCE() in cases where platform does not override.
Also convert ptep_get_lockless() into ptep_get() as well.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Dev Jain <dev.jain@arm.com>
Acked-by: Lance Yang <lance.yang@linux.dev>
Acked-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
Changes in V2:

- Replaced ptep_get_lockless() with ptep_get() per David

Changes in V1:

https://lore.kernel.org/all/20250930025246.1143340-1-anshuman.khandual@arm.com/

 mm/ptdump.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/mm/ptdump.c b/mm/ptdump.c
index b600c7f864b8..973020000096 100644
--- a/mm/ptdump.c
+++ b/mm/ptdump.c
@@ -31,7 +31,7 @@ static int ptdump_pgd_entry(pgd_t *pgd, unsigned long addr,
 			    unsigned long next, struct mm_walk *walk)
 {
 	struct ptdump_state *st = walk->private;
-	pgd_t val = READ_ONCE(*pgd);
+	pgd_t val = pgdp_get(pgd);
 
 #if CONFIG_PGTABLE_LEVELS > 4 && \
 		(defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
@@ -54,7 +54,7 @@ static int ptdump_p4d_entry(p4d_t *p4d, unsigned long addr,
 			    unsigned long next, struct mm_walk *walk)
 {
 	struct ptdump_state *st = walk->private;
-	p4d_t val = READ_ONCE(*p4d);
+	p4d_t val = p4dp_get(p4d);
 
 #if CONFIG_PGTABLE_LEVELS > 3 && \
 		(defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
@@ -77,7 +77,7 @@ static int ptdump_pud_entry(pud_t *pud, unsigned long addr,
 			    unsigned long next, struct mm_walk *walk)
 {
 	struct ptdump_state *st = walk->private;
-	pud_t val = READ_ONCE(*pud);
+	pud_t val = pudp_get(pud);
 
 #if CONFIG_PGTABLE_LEVELS > 2 && \
 		(defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS))
@@ -100,7 +100,7 @@ static int ptdump_pmd_entry(pmd_t *pmd, unsigned long addr,
 			    unsigned long next, struct mm_walk *walk)
 {
 	struct ptdump_state *st = walk->private;
-	pmd_t val = READ_ONCE(*pmd);
+	pmd_t val = pmdp_get(pmd);
 
 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
 	if (pmd_page(val) == virt_to_page(lm_alias(kasan_early_shadow_pte)))
@@ -121,7 +121,7 @@ static int ptdump_pte_entry(pte_t *pte, unsigned long addr,
 			    unsigned long next, struct mm_walk *walk)
 {
 	struct ptdump_state *st = walk->private;
-	pte_t val = ptep_get_lockless(pte);
+	pte_t val = ptep_get(pte);
 
 	if (st->effective_prot_pte)
 		st->effective_prot_pte(st, val);
-- 
2.30.2

Re: [PATCH V2] mm/ptdump: Replace READ_ONCE() with standard page table accessors

[David Hildenbrand]

On 01.10.25 06:25, Anshuman Khandual wrote:
> Replace READ_ONCE() with standard page table accessors i.e pxdp_get() which
> anyways default into READ_ONCE() in cases where platform does not override.
> Also convert ptep_get_lockless() into ptep_get() as well.
> 

Could have mentioned that no config that requires ptep_get_lockless() 
ends up enabling ptdump.

Acked-by: David Hildenbrand <david@redhat.com>

-- 
Cheers

David / dhildenb