diff mbox

[RFC,2/2] arm64: hugetlbpages: Correctly handle swap entries in huge_pte_offset()

Message ID 20170323125823.429-3-punit.agrawal@arm.com (mailing list archive)
State New, archived
Headers show

Commit Message

Punit Agrawal March 23, 2017, 12:58 p.m. UTC
huge_pte_offset() does not correctly handle poisoned or migration page
table entries. Not knowing the size of the hugepage entry being
requested only compounded the problem.

The recently added hstate parameter can be used to determine the size of
hugepage being accessed. Use the size to find the correct page table
entry to return when coming across a swap page table entry.

Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Cc: David Woods <dwoods@mellanox.com>
---
 arch/arm64/mm/hugetlbpage.c | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)
diff mbox

Patch

diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index 75d8cc3e138b..db108fa6e197 100644
--- a/arch/arm64/mm/hugetlbpage.c
+++ b/arch/arm64/mm/hugetlbpage.c
@@ -191,38 +191,39 @@  pte_t *huge_pte_alloc(struct mm_struct *mm,
 
 pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr, struct hstate *h)
 {
+	unsigned long sz = huge_page_size(h);
 	pgd_t *pgd;
 	pud_t *pud;
-	pmd_t *pmd = NULL;
-	pte_t *pte = NULL;
+	pmd_t *pmd;
+	pte_t *pte;
 
 	pgd = pgd_offset(mm, addr);
 	pr_debug("%s: addr:0x%lx pgd:%p\n", __func__, addr, pgd);
 	if (!pgd_present(*pgd))
 		return NULL;
+
 	pud = pud_offset(pgd, addr);
-	if (!pud_present(*pud))
+	if (pud_none(*pud) && sz != PUD_SIZE)
 		return NULL;
-
-	if (pud_huge(*pud))
+	else if (!pud_table(*pud))
 		return (pte_t *)pud;
+
+	if (sz == CONT_PMD_SIZE)
+		addr &= CONT_PMD_MASK;
+
 	pmd = pmd_offset(pud, addr);
-	if (!pmd_present(*pmd))
+	if (pmd_none(*pmd) &&
+	    !(sz == PMD_SIZE || sz == CONT_PMD_SIZE))
 		return NULL;
-
-	if (pte_cont(pmd_pte(*pmd))) {
-		pmd = pmd_offset(
-			pud, (addr & CONT_PMD_MASK));
-		return (pte_t *)pmd;
-	}
-	if (pmd_huge(*pmd))
+	else if (!pmd_table(*pmd))
 		return (pte_t *)pmd;
-	pte = pte_offset_kernel(pmd, addr);
-	if (pte_present(*pte) && pte_cont(*pte)) {
+
+	if (sz == CONT_PTE_SIZE) {
 		pte = pte_offset_kernel(
 			pmd, (addr & CONT_PTE_MASK));
 		return pte;
 	}
+
 	return NULL;
 }