@@ -158,9 +158,14 @@ static inline void pgd_set(pgd_t *pgdp, unsigned long val)
#define __swp_entry(type, offset) ((swp_entry_t) { \
((type) << _PAGE_BIT_SWAP_TYPE) \
| ((offset) << PTE_RPN_SHIFT) })
-
-#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val((pte)) })
-#define __swp_entry_to_pte(x) __pte((x).val)
+/*
+ * swp_entry_t should be arch independent. We build a swp_entry_t from
+ * swap type and offset we get from swap and convert that to pte to
+ * find a matching pte in linux page table.
+ * Clear bits not found in swap entries here
+ */
+#define __pte_to_swp_entry(pte) ((swp_entry_t) { pte_val((pte)) & ~_PAGE_PTE })
+#define __swp_entry_to_pte(x) __pte((x).val | _PAGE_PTE)
#ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
#define _PAGE_SWP_SOFT_DIRTY (1UL << (SWP_TYPE_BITS + _PAGE_BIT_SWAP_TYPE))
When converting a swp_entry_t to pte, we need to add _PAGE_PTE, because we later compare the pte with linux page table entries to find a matching pte. We do set _PAGE_PTE on pte entries on linux page table even if it is a swap entry. So add them when converting swp_entry_t to pte_t The stack trace can be anywhere below try_to_unuse() in mm/swapfile.c, since swapoff is circling around and around that function, reading from each used swap block into a page, then trying to find where that page belongs, looking at every non-file pte of every mm that ever swapped. Reported-by: Hugh Dickins <hughd@google.com> Suggested-by: Hugh Dickins <hughd@google.com> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> --- arch/powerpc/include/asm/book3s/64/pgtable.h | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-)