Replace raw READ_ONCE() dereferences of pgtable entries with corresponding standard page table accessors pxdp_get() in perf_get_pgtable_size(). These accessors default to READ_ONCE() on platforms that don't override them. So there is no functional change on such platforms. However arm64 platform is being extended to support 128 bit page tables via a new architecture feature i.e FEAT_D128 in which case READ_ONCE() will not provide required single copy atomic access for 128 bit page table entries. Although pxdp_get() accessors can later be overridden on arm64 platform to extend required single copy atomicity support on 128 bit entries. Cc: Andrew Morton Cc: David Hildenbrand Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Arnaldo Carvalho de Melo Cc: Namhyung Kim Cc: linux-perf-users@vger.kernel.org Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Acked-by: Peter Zijlstra (Intel) Signed-off-by: Anshuman Khandual --- This patch applies both on v7.0-rc1 and mm-unstable. Part of the D128 series but independent. Hence could be considered on its own. https://lore.kernel.org/all/20260224051153.3150613-5-anshuman.khandual@arm.com/ Collected Peter's tag from an off list conversation. 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 ac70d68217b6..4ee151cd2c6d 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -8422,7 +8422,7 @@ 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; @@ -8430,7 +8430,7 @@ 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; @@ -8438,7 +8438,7 @@ 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; -- 2.30.2