From cc38a27c88a0cafe5c4bc3e324071eb9d1663b75 Mon Sep 17 00:00:00 2001 From: Alexandre Ghiti Date: Thu, 14 Aug 2025 12:06:14 +0000 Subject: [PATCH] riscv: use an atomic xchg in pudp_huge_get_and_clear() Make sure we return the right pud value and not a value that could have been overwritten in between by a different core. Link: https://lkml.kernel.org/r/20250814-dev-alex-thp_pud_xchg-v1-1-b4704dfae206@rivosinc.com Fixes: c3cc2a4a3a23 ("riscv: Add support for PUD THP") Signed-off-by: Alexandre Ghiti Cc: Andrew Donnellan Cc: Signed-off-by: Andrew Morton --- arch/riscv/include/asm/pgtable.h | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h index 91697fbf1f901..e69346307e786 100644 --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -942,6 +942,17 @@ static inline int pudp_test_and_clear_young(struct vm_area_struct *vma, return ptep_test_and_clear_young(vma, address, (pte_t *)pudp); } +#define __HAVE_ARCH_PUDP_HUGE_GET_AND_CLEAR +static inline pud_t pudp_huge_get_and_clear(struct mm_struct *mm, + unsigned long address, pud_t *pudp) +{ + pud_t pud = __pud(atomic_long_xchg((atomic_long_t *)pudp, 0)); + + page_table_check_pud_clear(mm, pud); + + return pud; +} + static inline int pud_young(pud_t pud) { return pte_young(pud_pte(pud)); -- 2.51.0