Follow up to “I booted Linux 293k times”

A bug that was randomly hanging nbdkit tests was fixed after an extensive and frustrating investigation. At first, developers suspected a QEMU bug, but it was eventually concluded that the problem was likely in the Linux guest kernel. However, tracking down the kernel bug required a slow process of bisecting the kernel with a large number of commits. In the end, a hardware-speed dependent race condition was identified, and a fix was suggested by Thomas Gleixner. Although the patch that introduced the bug had already gone into several stable trees, the bug is now fixed.

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