3 files changed, 22 insertions, 7 deletions

diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index 8ac8e9fd5614..8e950cdff1a0 100644
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -1017,8 +1017,8 @@ int __devinit smp_prepare_cpu(int cpu)
         tsc_sync_disabled = 1;
 
         /* init low mem mapping */
-        memcpy(swapper_pg_dir, swapper_pg_dir + USER_PGD_PTRS,
-                        sizeof(swapper_pg_dir[0]) * KERNEL_PGD_PTRS);
+        clone_pgd_range(swapper_pg_dir, swapper_pg_dir + USER_PGD_PTRS,
+                        KERNEL_PGD_PTRS);
         flush_tlb_all();
         schedule_work(&task);
         wait_for_completion(&done);
diff --git a/arch/i386/mm/pgtable.c b/arch/i386/mm/pgtable.c
index bd2f7afc7a2a..dcdce2c6c532 100644
--- a/arch/i386/mm/pgtable.c
+++ b/arch/i386/mm/pgtable.c
@@ -207,19 +207,19 @@ void pgd_ctor(void *pgd, kmem_cache_t *cache, unsigned long unused)
 {
         unsigned long flags;
 
-        if (PTRS_PER_PMD == 1)
+        if (PTRS_PER_PMD == 1) {
+                memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
                 spin_lock_irqsave(&pgd_lock, flags);
+        }
 
-        memcpy((pgd_t *)pgd + USER_PTRS_PER_PGD,
+        clone_pgd_range((pgd_t *)pgd + USER_PTRS_PER_PGD,
                         swapper_pg_dir + USER_PTRS_PER_PGD,
-                        (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
-
+                        KERNEL_PGD_PTRS);
         if (PTRS_PER_PMD > 1)
                 return;
 
         pgd_list_add(pgd);
         spin_unlock_irqrestore(&pgd_lock, flags);
-        memset(pgd, 0, USER_PTRS_PER_PGD*sizeof(pgd_t));
 }
 
 /* never called when PTRS_PER_PMD > 1 */
diff --git a/include/asm-i386/pgtable.h b/include/asm-i386/pgtable.h
index d74185aee15b..47bc1ffa3d4c 100644
--- a/include/asm-i386/pgtable.h
+++ b/include/asm-i386/pgtable.h
@@ -278,6 +278,21 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr,
 }
 
 /*
+ * clone_pgd_range(pgd_t *dst, pgd_t *src, int count);
+ *
+ *  dst - pointer to pgd range anwhere on a pgd page
+ *  src - ""
+ *  count - the number of pgds to copy.
+ *
+ * dst and src can be on the same page, but the range must not overlap,
+ * and must not cross a page boundary.
+ */
+static inline void clone_pgd_range(pgd_t *dst, pgd_t *src, int count)
+{
+       memcpy(dst, src, count * sizeof(pgd_t));
+}
+
+/*
  * Macro to mark a page protection value as "uncacheable".  On processors which do not support
  * it, this is a no-op.
  */