[PATCH v3 04/22] perf/events: replace READ_ONCE() with standard page table accessors

[PATCH v3 04/22] perf/events: replace READ_ONCE() with standard page table accessors

[Samuel Holland]

From: Anshuman Khandual <anshuman.khandual@arm.com>

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.

Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: linux-perf-users@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Link: https://lore.kernel.org/r/20251006042622.1743675-1-anshuman.khandual@arm.com/
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
---

Changes in v3:
 - Replace my patch with Anshuman Khandual's patch from LKML

Changes in v2:
 - New patch for v2

 kernel/events/core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/events/core.c b/kernel/events/core.c
index 1fd347da9026..fa4f9165bd94 100644
--- a/kernel/events/core.c
+++ b/kernel/events/core.c
@@ -8122,7 +8122,7 @@ static u64 perf_get_pgtable_size(struct mm_struct *mm, unsigned long addr)
 	pte_t *ptep, pte;
 
 	pgdp = pgd_offset(mm, addr);
-	pgd = READ_ONCE(*pgdp);
+	pgd = pgdp_get(pgdp);
 	if (pgd_none(pgd))
 		return 0;
 
@@ -8130,7 +8130,7 @@ static u64 perf_get_pgtable_size(struct mm_struct *mm, unsigned long addr)
 		return pgd_leaf_size(pgd);
 
 	p4dp = p4d_offset_lockless(pgdp, pgd, addr);
-	p4d = READ_ONCE(*p4dp);
+	p4d = p4dp_get(p4dp);
 	if (!p4d_present(p4d))
 		return 0;
 
@@ -8138,7 +8138,7 @@ static u64 perf_get_pgtable_size(struct mm_struct *mm, unsigned long addr)
 		return p4d_leaf_size(p4d);
 
 	pudp = pud_offset_lockless(p4dp, p4d, addr);
-	pud = READ_ONCE(*pudp);
+	pud = pudp_get(pudp);
 	if (!pud_present(pud))
 		return 0;
 
-- 
2.47.2

Re: [PATCH v3 04/22] perf/events: replace READ_ONCE() with standard page table accessors

[David Hildenbrand (Red Hat)]

On 13.11.25 02:45, Samuel Holland wrote:
> From: Anshuman Khandual <anshuman.khandual@arm.com>
> 
> 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.
> 
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
> Cc: Namhyung Kim <namhyung@kernel.org>
> Cc: linux-perf-users@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> Link: https://lore.kernel.org/r/20251006042622.1743675-1-anshuman.khandual@arm.com/
> Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
> ---

Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>

-- 
Cheers

David