BUG_ON() has been discouraged for debugging kernel problems for a very long time. However, there are still several BUG_ON() usages in the Linux Kernel. A late commit to Kernel 4.8 is one such case, and is now causing a lot of headaches with the release that came out on October 2nd, 2016. This BUG_ON() is triggered when CONFIG_DEBUG_VM is enabled. Some distributions such as the standard Fedora Kernel config enable it by default. Linus Torvalds has discovered that once this BUG_ON() triggers, the machine will have problems handling kernel paging requests and report that a reboot is required to fix a recursive fault from which the machine will never recover! Here’s his direct quote The reason the machine *dies* from that thing is that we end up then immediately having a
BUG: unable to handle kernel paging request at ffffffffb70bdaa8
and then a
Fixing recursive fault but reboot is needed!
and the machine will never recover. Fixing this bug is number one priority for Linus […]