Cleanup munmap a lot. Fix Intel P4 TLB corruptions on SMP.

Special thanks to Intel for support and traces.

include/asm-generic/tlb.h

@@ -44,18 +44,12 @@ extern mmu_gather_t	mmu_gathers[NR_CPUS];
 static inline mmu_gather_t *tlb_gather_mmu(struct mm_struct *mm)
 {
 	mmu_gather_t *tlb = &mmu_gathers[smp_processor_id()];
-	unsigned long nr;
 
 	tlb->mm = mm;
 	tlb->freed = 0;
 
-	/* Use fast mode if this MM only exists on this CPU */
-	nr = ~0UL;
-#ifdef CONFIG_SMP
-	if (mm->cpu_vm_mask != (1<<smp_processor_id()))
-		nr = 0UL;
-#endif
-	tlb->nr = nr;
+	/* Use fast mode if only one CPU is online */
+	tlb->nr = smp_num_cpus > 1 ? 0UL : ~0UL;
 	return tlb;
 }