The pmd_none check does not catch hugepage collapse, nor does the
pmd_present check in pmd_trans_huge, because hugepage collapse sets
!_PAGE_PRESENT && _PAGE_INVALID (which results in !pmd_none and
pmd_present).
Aneesh noticed we might need this check as well.
---
arch/powerpc/mm/pgtable.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
index db4a6253df92..7a702d21400a 100644
--- a/arch/powerpc/mm/pgtable.c
+++ b/arch/powerpc/mm/pgtable.c
@@ -372,13 +372,20 @@ pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
pdshift = PMD_SHIFT;
pmdp = pmd_offset(&pud, ea);
pmd = READ_ONCE(*pmdp);
- /*
- * A hugepage collapse is captured by pmd_none, because
- * it mark the pmd none and do a hpte invalidate.
- */
+
if (pmd_none(pmd))
return NULL;
+#ifdef CONFIG_PPC_BOOK3S_64
+ if (pmd_val(pmd) & (_PAGE_PRESENT|_PAGE_INVALID) == _PAGE_INVALID) {
+ /*
+ * A hugepage collapse is captured by this condition, see
+ * pmdp_invalidate.
+ */
+ return NULL;
+ }
+#endif
+
if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) {
if (is_thp)
*is_thp = true;
--
2.20.1
