Actually, the code snippet, without context is not an obvious attempt. It is a cleverly hidden attempt that COULD be a genuine error.
Sir, you have not looked into this one bit and are spewing hot air without any substance.
The ANDed limitation of uid being root makes zero sense. Why limit root in particular?
Not to mention that __WALL already has __WCLONE flag in it, what would possibly be the point of that? Aside from the obvious assignment as comparison, which of course seemingly could be a typo, the rest of it is something no sane kernel developer would have any reason what so ever to put in there.
That is why it is a backdoor insertion without any reasonable doubt. Not because of the mere = in place of ==, which I still typo regularly after 25 years of C. Thankfully these days compiler warnings and various static analyzers catch that nonsense.