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Howlett" , Anshuman Khandual , Lance Yang , Wei Yang , Dev Jain , Samuel Holland Subject: [PATCH v3 02/22] mm: replace READ_ONCE() with standard page table accessors Date: Wed, 12 Nov 2025 17:45:15 -0800 Message-ID: <20251113014656.2605447-3-samuel.holland@sifive.com> X-Mailer: git-send-email 2.47.2 In-Reply-To: <20251113014656.2605447-1-samuel.holland@sifive.com> References: <20251113014656.2605447-1-samuel.holland@sifive.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Anshuman Khandual Replace all READ_ONCE() with a standard page table accessors i.e pxdp_get() that defaults into READ_ONCE() in cases where platform does not override. Link: https://lkml.kernel.org/r/20251007063100.2396936-1-anshuman.khandual@= arm.com Signed-off-by: Anshuman Khandual Acked-by: David Hildenbrand Reviewed-by: Lance Yang Reviewed-by: Wei Yang Cc: Dev Jain Signed-off-by: Andrew Morton Signed-off-by: Samuel Holland Reviewed-by: Dev Jain --- Changes in v3: - New patch for v3 (cherry-picked from linux-next) mm/gup.c | 10 +++++----- mm/hmm.c | 2 +- mm/memory.c | 4 ++-- mm/mprotect.c | 2 +- mm/sparse-vmemmap.c | 2 +- mm/vmscan.c | 2 +- 6 files changed, 11 insertions(+), 11 deletions(-) diff --git a/mm/gup.c b/mm/gup.c index a8ba5112e4d0..b46112d36f7e 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -950,7 +950,7 @@ static struct page *follow_pud_mask(struct vm_area_stru= ct *vma, struct mm_struct *mm =3D vma->vm_mm; =20 pudp =3D pud_offset(p4dp, address); - pud =3D READ_ONCE(*pudp); + pud =3D pudp_get(pudp); if (!pud_present(pud)) return no_page_table(vma, flags, address); if (pud_leaf(pud)) { @@ -975,7 +975,7 @@ static struct page *follow_p4d_mask(struct vm_area_stru= ct *vma, p4d_t *p4dp, p4d; =20 p4dp =3D p4d_offset(pgdp, address); - p4d =3D READ_ONCE(*p4dp); + p4d =3D p4dp_get(p4dp); BUILD_BUG_ON(p4d_leaf(p4d)); =20 if (!p4d_present(p4d) || p4d_bad(p4d)) @@ -3060,7 +3060,7 @@ static int gup_fast_pud_range(p4d_t *p4dp, p4d_t p4d,= unsigned long addr, =20 pudp =3D pud_offset_lockless(p4dp, p4d, addr); do { - pud_t pud =3D READ_ONCE(*pudp); + pud_t pud =3D pudp_get(pudp); =20 next =3D pud_addr_end(addr, end); if (unlikely(!pud_present(pud))) @@ -3086,7 +3086,7 @@ static int gup_fast_p4d_range(pgd_t *pgdp, pgd_t pgd,= unsigned long addr, =20 p4dp =3D p4d_offset_lockless(pgdp, pgd, addr); do { - p4d_t p4d =3D READ_ONCE(*p4dp); + p4d_t p4d =3D p4dp_get(p4dp); =20 next =3D p4d_addr_end(addr, end); if (!p4d_present(p4d)) @@ -3108,7 +3108,7 @@ static void gup_fast_pgd_range(unsigned long addr, un= signed long end, =20 pgdp =3D pgd_offset(current->mm, addr); do { - pgd_t pgd =3D READ_ONCE(*pgdp); + pgd_t pgd =3D pgdp_get(pgdp); =20 next =3D pgd_addr_end(addr, end); if (pgd_none(pgd)) diff --git a/mm/hmm.c b/mm/hmm.c index 87562914670a..a56081d67ad6 100644 --- a/mm/hmm.c +++ b/mm/hmm.c @@ -491,7 +491,7 @@ static int hmm_vma_walk_pud(pud_t *pudp, unsigned long = start, unsigned long end, /* Normally we don't want to split the huge page */ walk->action =3D ACTION_CONTINUE; =20 - pud =3D READ_ONCE(*pudp); + pud =3D pudp_get(pudp); if (!pud_present(pud)) { spin_unlock(ptl); return hmm_vma_walk_hole(start, end, -1, walk); diff --git a/mm/memory.c b/mm/memory.c index b59ae7ce42eb..0c295e2fe8e8 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -6690,12 +6690,12 @@ int follow_pfnmap_start(struct follow_pfnmap_args *= args) goto out; =20 p4dp =3D p4d_offset(pgdp, address); - p4d =3D READ_ONCE(*p4dp); + p4d =3D p4dp_get(p4dp); if (p4d_none(p4d) || unlikely(p4d_bad(p4d))) goto out; =20 pudp =3D pud_offset(p4dp, address); - pud =3D READ_ONCE(*pudp); + pud =3D pudp_get(pudp); if (pud_none(pud)) goto out; if (pud_leaf(pud)) { diff --git a/mm/mprotect.c b/mm/mprotect.c index 113b48985834..988c366137d5 100644 --- a/mm/mprotect.c +++ b/mm/mprotect.c @@ -599,7 +599,7 @@ static inline long change_pud_range(struct mmu_gather *= tlb, break; } =20 - pud =3D READ_ONCE(*pudp); + pud =3D pudp_get(pudp); if (pud_none(pud)) continue; =20 diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c index dbd8daccade2..37522d6cb398 100644 --- a/mm/sparse-vmemmap.c +++ b/mm/sparse-vmemmap.c @@ -439,7 +439,7 @@ int __meminit vmemmap_populate_hugepages(unsigned long = start, unsigned long end, return -ENOMEM; =20 pmd =3D pmd_offset(pud, addr); - if (pmd_none(READ_ONCE(*pmd))) { + if (pmd_none(pmdp_get(pmd))) { void *p; =20 p =3D vmemmap_alloc_block_buf(PMD_SIZE, node, altmap); diff --git a/mm/vmscan.c b/mm/vmscan.c index b2fc8b626d3d..2239de111fa6 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -3773,7 +3773,7 @@ static int walk_pud_range(p4d_t *p4d, unsigned long s= tart, unsigned long end, pud =3D pud_offset(p4d, start & P4D_MASK); restart: for (i =3D pud_index(start), addr =3D start; addr !=3D end; i++, addr =3D= next) { - pud_t val =3D READ_ONCE(pud[i]); + pud_t val =3D pudp_get(pud + i); =20 next =3D pud_addr_end(addr, end); =20 --=20 2.47.2