MS_INVALIDATE
str = msync_sync("garbage", MS_INVALIDATE);
msync(a2, AREA, MS_SYNC|MS_INVALIDATE);
if ((flags & ~(MS_ASYNC | MS_SYNC | MS_INVALIDATE)) != 0 ||
(flags & (MS_ASYNC | MS_SYNC | MS_INVALIDATE)) == 0 ||
if (flags & MS_INVALIDATE)