LWN has a cool feature where any subscriber can make these "subscriber links" to share an article with a friend/coworker, a relevant mailing list, or sometimes even HN. See https://lwn.net/op/FAQ.lwn#slinks for details.

In this case, the link was posted by Jon Corbet, who is LWN's main editor and developer.

The submitter is the LWN editor and the author of the post.

They allow subscribers to share the links. But they do suggest you do this on limited scale and conscientiously.