It's precisely what thrice and hunghang have said: you have your playback options set to include clipping of both highlights and shadows.
Personally, I would leave them on, especially the highlights as the M9's sensor really does have a few "oh, bother" moments with regards to highlights.
Why do you have the camera set to pump out B+W JPGs, if I may ask? The camera comes with Adobe Lightroom, which will do a far better, more flexible job with RAW to BW conversions, than the M9 could ever do.
I'm not criticizing, I'm trying to understand your motivation and subsequent choice "flowchart" so that we may all help you.
To turn off the clipping options, press "MENU" and scroll down to the "Histogram" category.
Press set, then scroll down to "Clipping" where you can set the options for
"Off"
"Overexposure only"
"Over / underexposure"
Note how there's no "underexposure only" option ;-) The M9's sensor is a shadow-lifting beast, really.