Extra padding/margin added to DatePicker on Android 7.1.1

Add Style with AlertDialog.Builder like as follow.

AlertDialog.Builder builder = new AlertDialog.Builder(UserAttributesActivity.this, android.R.style.Theme_DeviceDefault_Light_Dialog_NoActionBar);

@Ankita is right, but if you are using AppCompat things are a bit more involved:

Define a new style and extend AppCompat's Light.Dialog style

<style name="DatePickerDialogStyle" parent="@style/Theme.AppCompat.Light.Dialog">
    ...
</style>

Then add attributes to mimic the NoActionBar part:

<style name="DatePickerDialogStyle" parent="@style/Theme.AppCompat.Light.Dialog">
    <item name="windowActionBar">false</item>
    <item name="windowNoTitle">true</item>
</style>

Lastly, now that you are no longer getting app compat colors from your AppTheme, copy them over to your new theme:

<style name="AppTheme" parent="Theme.AppCompat.Light">
    <item name="colorPrimary">@color/primary</item>
    <item name="colorPrimaryDark">@color/primary_dark</item>
    <item name="colorAccent">@color/accent</item>
</style>

<style name="DatePickerDialogStyle" parent="@style/Theme.AppCompat.Light.Dialog">
    <item name="windowActionBar">false</item>
    <item name="windowNoTitle">true</item>
    <item name="colorPrimary">@color/primary<item>
    <item name="colorPrimaryDark">@color/primary_darkitem>
    <item name="colorAccent">@color/accent</item>
</style>

Then apply this new theme:

AlertDialog.Builder builder 
    = new AlertDialog.Builder(UserAttributesActivity.this,
    DatePickerDialogStyle);