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

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Message-ID: <20251113014656.2605447-5-samuel.holland@sifive.com>
Date: Wed, 12 Nov 2025 17:45:17 -0800
From: Samuel Holland <samuel.holland@...ive.com>
To: Palmer Dabbelt <palmer@...belt.com>,
	Paul Walmsley <pjw@...nel.org>,
	linux-riscv@...ts.infradead.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...hat.com>,
	linux-mm@...ck.org
Cc: devicetree@...r.kernel.org,
	Suren Baghdasaryan <surenb@...gle.com>,
	linux-kernel@...r.kernel.org,
	Mike Rapoport <rppt@...nel.org>,
	Michal Hocko <mhocko@...e.com>,
	Conor Dooley <conor@...nel.org>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Alexandre Ghiti <alex@...ti.fr>,
	Emil Renner Berthing <kernel@...il.dk>,
	Rob Herring <robh+dt@...nel.org>,
	Vlastimil Babka <vbabka@...e.cz>,
	"Liam R . Howlett" <Liam.Howlett@...cle.com>,
	Anshuman Khandual <anshuman.khandual@....com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	linux-perf-users@...r.kernel.org,
	Samuel Holland <samuel.holland@...ive.com>
Subject: [PATCH v3 04/22] perf/events: replace READ_ONCE() with standard page table accessors

From: Anshuman Khandual <anshuman.khandual@....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@...radead.org>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: linux-perf-users@...r.kernel.org
Cc: linux-kernel@...r.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>
Link: https://lore.kernel.org/r/20251006042622.1743675-1-anshuman.khandual@arm.com/
Signed-off-by: Samuel Holland <samuel.holland@...ive.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