Despite the snowstorms knocking the power out in Portland, where Linus Torvalds’ house is located, Torvalds and contributors managed to release the version RC 5.12 on time. However, Torvalds announced in the mailing list that the first release candidate of Linux kernel 5.12 includes a bug that can affect a computer’s filesystem.
Torvalds announced that in his public git, the “v5.12-rc1” tag has been renamed to “v5.12-rc1-dontuse”. The release includes a “nasty bug” and swap files stopped working and the offset of the start of the swap file was lost. Swapping still happened, but it happened to the wrong part of the filesystem. Linus Torvalds, Developer, Linux kernel, said,
“Yes, this is very unfortunate, but it really wasn’t a very obvious bug, and it didn’t even show up in normal testing, exactly because swapfiles just aren’t normal. So I’m not blaming the developers in question, and it also wasn’t due to the odd timing of the merge window, it was just simply an unusually nasty bug that did get caught and is fixed in the current tree.
Now, there’s a couple of additional reasons for me writing this note other than just “don’t run 5.12-rc1 if you use a swapfile”. Because it’s more than just “ok, we all know the merge window is when all the new scary code gets merged, and rc1 can be a bit scary and not work for everybody”. Yes, rc1 tends to be buggier than later rc’s, we are all used to that, but honestly, most of the time the bugs are much smaller annoyances than this time.”