Add hooks to allow a paravirt implementation to track the lifetime of
an mm.

--- a/arch/i386/kernel/paravirt.c
+++ b/arch/i386/kernel/paravirt.c

@@ -706,6 +706,10 @@ struct paravirt_ops paravirt_ops = {
 	.irq_enable_sysexit = native_irq_enable_sysexit,
 	.iret = native_iret,
 
+	.dup_mmap = (void *)native_nop,
+	.exit_mmap = (void *)native_nop,
+	.activate_mm = (void *)native_nop,
+
 	.startup_ipi_hook = (void *)native_nop,
 };

===================================================================

--- a/include/asm-i386/mmu_context.h
+++ b/include/asm-i386/mmu_context.h

@@ -5,6 +5,7 @@
 #include <asm/atomic.h>
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
+#include <asm/paravirt.h>
 
 /*
  * Used for LDT copy/destruction.

@@ -65,7 +66,10 @@ static inline void switch_mm(struct mm_s
 #define deactivate_mm(tsk, mm)			\
 	asm("movl %0,%%gs": :"r" (0));
 
-#define activate_mm(prev, next) \
-	switch_mm((prev),(next),NULL)
+#define activate_mm(prev, next)				\
+	do {						\
+		arch_activate_mm(prev, next);		\
+		switch_mm((prev),(next),NULL);		\
+	} while(0);

 #endif /* CONFIG_PARAVIRT */
 #endif	/* __ASM_PARAVIRT_H */
===================================================================

--- a/include/linux/sched.h
+++ b/include/linux/sched.h

@@ -374,6 +374,12 @@ struct mm_struct {
 	rwlock_t		ioctx_list_lock;
 	struct kioctx		*ioctx_list;
 };
+
+#ifndef __HAVE_ARCH_MM_LIFETIME
+#define arch_activate_mm(prev, next)	do {} while(0)
+#define arch_dup_mmap(oldmm, mm)	do {} while(0)
+#define arch_exit_mmap(mm)		do {} while(0)
+#endif

 struct sighand_struct {
 	atomic_t		count;
===================================================================

--- a/kernel/fork.c
+++ b/kernel/fork.c

@@ -286,6 +286,7 @@ static inline int dup_mmap(struct mm_str
 		if (retval)
 			goto out;
 	}
+	arch_dup_mmap(oldmm, mm);
 	retval = 0;
 out:
 	up_write(&mm->mmap_sem);

===================================================================

--- a/mm/mmap.c
+++ b/mm/mmap.c

@@ -1976,6 +1976,8 @@ void exit_mmap(struct mm_struct *mm)
 	struct vm_area_struct *vma = mm->mmap;
 	unsigned long nr_accounted = 0;
 	unsigned long end;
+
+	arch_exit_mmap(mm);
 
 	lru_add_drain();
 	flush_cache_mm(mm);