Fix lazy mode vmalloc synchronization for paravirt

Touching vmalloc memory in the middle of a lazy mode update can generate
a kernel PDE update, which must be flushed immediately.  The fix is to
leave lazy mode when doing a vmalloc sync.
Signed-off-by: NZachary Amsden <zach@vmware.com>
Acked-by: NJeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/i386/mm/fault.c

@@ -249,9 +249,10 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
 	pmd_k = pmd_offset(pud_k, address);
 	if (!pmd_present(*pmd_k))
 		return NULL;
-	if (!pmd_present(*pmd))
+	if (!pmd_present(*pmd)) {
 		set_pmd(pmd, *pmd_k);
-	else
+		arch_flush_lazy_mmu_mode();
+	} else
 		BUG_ON(pmd_page(*pmd) != pmd_page(*pmd_k));
 	return pmd_k;
 }