The page table manipulation code seems to have grown a couple of
sites that are looking for empty PTEs. Just in case one of these
entries got a stray bit set, use pte_none() instead of checking
for a zero pte_val().
The use pte_same() makes me a bit nervous. If we were doing a
pte_same() check against two cleared entries and one of them had
a stray bit set, it might fail the pte_same() check. But, I
don't think we ever _do_ pte_same() for cleared entries. It is
almost entirely used for checking for races in fault-in paths.
---
b/arch/x86/mm/init_64.c | 12 ++++++------
b/arch/x86/mm/pageattr.c | 2 +-
b/arch/x86/mm/pgtable_32.c | 2 +-
3 files changed, 8 insertions(+), 8 deletions(-)
diff -puN arch/x86/mm/init_64.c~knl-strays-50-pte_val-cleanups
arch/x86/mm/init_64.c
--- a/arch/x86/mm/init_64.c~knl-strays-50-pte_val-cleanups 2016-07-01
10:42:07.781811987 -0700
+++ b/arch/x86/mm/init_64.c 2016-07-01 10:42:07.788812305 -0700
@@ -354,7 +354,7 @@ phys_pte_init(pte_t *pte_page, unsigned
* pagetable pages as RO. So assume someone who pre-setup
* these mappings are more intelligent.
*/
- if (pte_val(*pte)) {
+ if (!pte_none(*pte)) {
if (!after_bootmem)
pages++;
continue;
@@ -396,7 +396,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned
continue;
}
- if (pmd_val(*pmd)) {
+ if (!pmd_none(*pmd)) {
if (!pmd_large(*pmd)) {
spin_lock(&init_mm.page_table_lock);
pte = (pte_t *)pmd_page_vaddr(*pmd);
@@ -470,7 +470,7 @@ phys_pud_init(pud_t *pud_page, unsigned
continue;
}
- if (pud_val(*pud)) {
+ if (!pud_none(*pud)) {
if (!pud_large(*pud)) {
pmd = pmd_offset(pud, 0);
last_map_addr = phys_pmd_init(pmd, addr, end,
@@ -673,7 +673,7 @@ static void __meminit free_pte_table(pte
for (i = 0; i < PTRS_PER_PTE; i++) {
pte = pte_start + i;
- if (pte_val(*pte))
+ if (!pte_none(*pte))
return;
}
@@ -691,7 +691,7 @@ static void __meminit free_pmd_table(pmd
for (i = 0; i < PTRS_PER_PMD; i++) {
pmd = pmd_start + i;
- if (pmd_val(*pmd))
+ if (!pmd_none(*pmd))
return;
}
@@ -710,7 +710,7 @@ static bool __meminit free_pud_table(pud
for (i = 0; i < PTRS_PER_PUD; i++) {
pud = pud_start + i;
- if (pud_val(*pud))
+ if (!pud_none(*pud))
return false;
}
diff -puN arch/x86/mm/pageattr.c~knl-strays-50-pte_val-cleanups
arch/x86/mm/pageattr.c
--- a/arch/x86/mm/pageattr.c~knl-strays-50-pte_val-cleanups 2016-07-01
10:42:07.783812078 -0700
+++ b/arch/x86/mm/pageattr.c 2016-07-01 10:42:07.789812350 -0700
@@ -1185,7 +1185,7 @@ repeat:
return __cpa_process_fault(cpa, address, primary);
old_pte = *kpte;
- if (!pte_val(old_pte))
+ if (pte_none(old_pte))
return __cpa_process_fault(cpa, address, primary);
if (level == PG_LEVEL_4K) {
diff -puN arch/x86/mm/pgtable_32.c~knl-strays-50-pte_val-cleanups
arch/x86/mm/pgtable_32.c
--- a/arch/x86/mm/pgtable_32.c~knl-strays-50-pte_val-cleanups 2016-07-01
10:42:07.785812169 -0700
+++ b/arch/x86/mm/pgtable_32.c 2016-07-01 10:42:07.789812350 -0700
@@ -47,7 +47,7 @@ void set_pte_vaddr(unsigned long vaddr,
return;
}
pte = pte_offset_kernel(pmd, vaddr);
- if (pte_val(pteval))
+ if (!pte_none(pteval))
set_pte_at(&init_mm, vaddr, pte, pteval);
else
pte_clear(&init_mm, vaddr, pte);
_
