1 files changed, 7 insertions, 4 deletions

diff --git a/include/asm-x86/pgtable-3level.h b/include/asm-x86/pgtable-3level.h
index ed4c6f0e57ec..ad71960bca3a 100644
--- a/include/asm-x86/pgtable-3level.h
+++ b/include/asm-x86/pgtable-3level.h
@@ -93,17 +93,20 @@ static inline void native_pmd_clear(pmd_t *pmd)
 
 static inline void pud_clear(pud_t *pudp)
 {
+        unsigned long pgd;
+
         set_pud(pudp, __pud(0));
 
         /*
          * Pentium-II erratum A13: in PAE mode we explicitly have to flush
          * the TLB via cr3 if the top-level pgd is changed...
          *
-         * XXX I don't think we need to worry about this here, since
-         * when clearing the pud, the calling code needs to flush the
-         * tlb anyway.  But do it now for safety's sake. - jsgf
+         * Make sure the pud entry we're updating is within the
+         * current pgd to avoid unnecessary TLB flushes.
          */
-        write_cr3(read_cr3());
+        pgd = read_cr3();
+        if (__pa(pudp) >= pgd && __pa(pudp) < (pgd + sizeof(pgd_t)*PTRS_PER_PGD))
+                write_cr3(pgd);
 }
 
 #define pud_page(pud) \