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riscv: Use an atomic xchg in pudp_huge_get_and_clear()

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Make sure we return the right pud value and not a value that could
have been overwritten in between by a different core.

Fixes: c3cc2a4a3a ("riscv: Add support for PUD THP")
Cc: stable@vger.kernel.org
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Link: https://lore.kernel.org/r/20250814-dev-alex-thp_pud_xchg-v1-1-b4704dfae206@rivosinc.com
[pjw@kernel.org: use xchg rather than atomic_long_xchg; avoid atomic op for !CONFIG_SMP like x86]
Signed-off-by: Paul Walmsley <pjw@kernel.org>
This commit is contained in:
Alexandre Ghiti
2025-09-23 18:25:52 -06:00
committed by Paul Walmsley
parent a03ee11b8f
commit 546e42c8c6
1 changed files with 17 additions and 0 deletions
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17
arch/riscv/include/asm/pgtable.h
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@@ -942,6 +942,23 @@ 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)
{
#ifdef CONFIG_SMP
pud_t pud = __pud(xchg(&pudp->pud, 0));
#else
pud_t pud = *pudp;
pud_clear(pudp);
#endif
page_table_check_pud_clear(mm, pud);
return pud;
}
static inline int pud_young(pud_t pud)
{
return pte_young(pud_pte(pud));