Change pte_clear_full to a more appropriately named pte_clear_not_present,
allowing optimizations when not-present mapping changes need not be
reflected in the hardware TLB for protected page table modes. There is
also another case that can use it in the fremap code.
Signed-off-by: Zachary Amsden <zach at vmware.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy at xensource.com>
---
include/asm-generic/pgtable.h | 4 ++--
mm/fremap.c | 2 +-
mm/memory.c | 2 +-
3 files changed, 4 insertions(+), 4 deletions(-)
===================================================================
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -110,8 +110,13 @@ do { \
})
#endif
-#ifndef __HAVE_ARCH_PTE_CLEAR_FULL
-#define pte_clear_full(__mm, __address, __ptep, __full) \
+/*
+ * Some architectures may be able to avoid expensive synchronization
+ * primitives when modifications are made to PTE's which are already
+ * not present, or in the process of an address space destruction.
+ */
+#ifndef __HAVE_ARCH_PTE_CLEAR_NOT_PRESENT_FULL
+#define pte_clear_not_present_full(__mm, __address, __ptep, __full) \
do { \
pte_clear((__mm), (__address), (__ptep)); \
} while (0)
===================================================================
--- a/mm/fremap.c
+++ b/mm/fremap.c
@@ -39,7 +39,7 @@ static int zap_pte(struct mm_struct *mm,
} else {
if (!pte_file(pte))
free_swap_and_cache(pte_to_swp_entry(pte));
- pte_clear(mm, addr, ptep);
+ pte_clear_not_present_full(mm, addr, ptep, 0);
}
return !!page;
}
===================================================================
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -689,7 +689,7 @@ static unsigned long zap_pte_range(struc
continue;
if (!pte_file(ptent))
free_swap_and_cache(pte_to_swp_entry(ptent));
- pte_clear_full(mm, addr, pte, tlb->fullmm);
+ pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
add_mm_rss(mm, file_rss, anon_rss);
