ScrollState.kt

//Saving scroll state
val position = linearLayoutManager.findFirstVisibleItemPosition()
val offset = linearLayoutManager.getChildAt(0).let {
    if (it == null) 0 else it.top - linearLayoutManager.paddingTop
}
postFeedViewModel.scrollState = ScrollState.of(position, offset)

//Restoring scroll state
val scrollState = postFeedViewModel.scrollState
linearLayoutManager.scrollToPositionWithOffset(scrollState.position, scrollState.offset)

//ViewModel
class PostFeedViewModel() : ViewModel {
    ...

    var scrollState: ScrollState
        get() = ScrollState.of(
                Preference.get(KEY_POST_SCROLL_POSITION, 0),
                Preference.get(KEY_POST_SCROLL_OFFSET, 0)
        )
        set(scrollState) {
            Preference.put(KEY_POST_SCROLL_POSITION, scrollState.position)
            Preference.put(KEY_POST_SCROLL_OFFSET, scrollState.offset)
        }
}