x86: tlb flush avoid superflous leave_mm()

x86: tlb flush avoid superflous leave_mm()

If just one page VA tlb is required to be flushed and current task is in
lazy TLB state, doing leave_mm() is superfluous because it flushes the
whole TLB.  This can reduce some TLB miss.

Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>