Smartobject size to 100%

What do you mean by 100%.  and is the smart object a Placed image file. Place scale smart objects,  In fact place may scale a smart object twice.  Once because there are different print resolution  in the Place image File the  document it is placed into a document and second second scaling if the smart object layer does not fit on canvas and your Photoshop preferences is  set to resize during Place. 

Script can scale a smart  layer to fill some area and mask  it to the area aspect ratio and shape.  I do that all the time.  Scaling a  smart object layer object transform to 100% may not be the size you are expecting the object  to be because Place may have scaled the object because of different resolution are involve.  Smart object layer implementation is more complex then most users think.

New versions of Photoshop have reset place layers transform I do not know if that will reset the PPI scaling Place may as well at place resize and user transform. It may I did not test that though.

I just tested reset place layers transform will reset all transforming done to the smart object sizing  and warping but positioning is not changed  so if the  transforming also move the positioning that will not be reset.

A fuction call/function that you will find on this forum in multiple scripts, where varSomeFile may be a variable to a single file or multiple files:

placeFile(varSomeFile, 100);

function placeFile(file, scale) {
    var idPlc = charIDToTypeID("Plc ");
    var desc2 = new ActionDescriptor();
    var idnull = charIDToTypeID("null");
    desc2.putPath(idnull, new File(file));
    var idFTcs = charIDToTypeID("FTcs");
    var idQCSt = charIDToTypeID("QCSt");
    var idQcsa = charIDToTypeID("Qcsa");
    desc2.putEnumerated(idFTcs, idQCSt, idQcsa);
    var idOfst = charIDToTypeID("Ofst");
    var desc3 = new ActionDescriptor();
    var idHrzn = charIDToTypeID("Hrzn");
    var idPxl = charIDToTypeID("#Pxl");
    desc3.putUnitDouble(idHrzn, idPxl, 0.000000);
    var idVrtc = charIDToTypeID("Vrtc");
    var idPxl = charIDToTypeID("#Pxl");
    desc3.putUnitDouble(idVrtc, idPxl, 0.000000);
    var idOfst = charIDToTypeID("Ofst");
    desc2.putObject(idOfst, idOfst, desc3);
    var idWdth = charIDToTypeID("Wdth");
    var idPrc = charIDToTypeID("#Prc");
    desc2.putUnitDouble(idWdth, idPrc, scale);
    var idHght = charIDToTypeID("Hght");
    var idPrc = charIDToTypeID("#Prc");
    desc2.putUnitDouble(idHght, idPrc, scale);
    var idAntA = charIDToTypeID("AntA");
    desc2.putBoolean(idAntA, true);
    executeAction(idPlc, desc2, DialogModes.NO);
}

runMenuItem(stringIDToTypeID('placedLayerResetTransforms'))