Swapoff after swapping hangs on the G5. That's because the _PAGE_PTE
bit, added by set_pte_at(), is not expected by swapoff: so swap ptes
cannot be recognized.
I'm not sure whether a swap pte should or should not have _PAGE_PTE set:
this patch assumes not, and fixes set_pte_at() to set _PAGE_PTE only on
present entries.
But if that's wrong, a reasonable alternative would be to
#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)
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
---
arch/powerpc/mm/pgtable.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- 4.4-next/arch/powerpc/mm/pgtable.c 2016-01-06 11:54:01.477512251 -0800
+++ linux/arch/powerpc/mm/pgtable.c 2016-01-09 13:51:15.793485717 -0800
@@ -180,9 +180,10 @@ void set_pte_at(struct mm_struct *mm, un
VM_WARN_ON((pte_val(*ptep) & (_PAGE_PRESENT | _PAGE_USER)) ==
(_PAGE_PRESENT | _PAGE_USER));
/*
- * Add the pte bit when tryint set a pte
+ * Add the pte bit when setting a pte (not a swap entry)
*/
- pte = __pte(pte_val(pte) | _PAGE_PTE);
+ if (pte_val(pte) & _PAGE_PRESENT)
+ pte = __pte(pte_val(pte) | _PAGE_PTE);
/* Note: mm->context.id might not yet have been assigned as
* this context might not have been activated yet when this
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