Just a word of caution: I've tried replacing the mitigation patch (which I had been using for 18 months) with the author's minimal fix (the first out of the 6 patches, which is supposed to fix the issue) and I've immediately ran into a deadlock while building Poly/ML 5.9 (3 times, in fact), whereas previously I hadn't encountered this bug before, despite having built Poly/ML many times.

This was on a 32-core machine with lots of background compilation going on at the same time (i.e. with a high load).

It could be a coincidence or an unrelated bug, but it's also possible that the author's patch might not fix the issue completely.