The one in dget() is known not to trigger - it's been there for a long time.
My problem with new BUG_ON's is that they get added thinking "no way will
this trigger" and lo, they do trigger and lots of people get their testing
disrupted for a whole release.
Long-standing checks like the one in dget() should perhaps be removed now
that we know they don't trigger - move them under some CONFIG_DEBUG_foo
option.
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