On Mon, 28 Oct 2019 at 14:23, Mouse <mo...@rodents-montreal.org> wrote: > > > To provide a bit more context: this code path with the potential > > division by zero has been in the tree for over a decade; [...] > > I once found I had a disk that was just broken enough to appear as a > disk, butit reported itself as having zero something (zero > sectors/track? zero tracks/cylinder? whatever) which provoked a > divide-by-zero. I of course patched this in my tree. (This was in > 2012, but it was under 1.4T, so I don't think I bothered reporting it > anywhere. I don't recall trying the same disk on something more > recent, though I also don't recall why not. I don't find comparable > commits in my other trees, so if I did try it, it presumably didn't > crash the relevant kernel(s).) > > So, while I agree that there are vanishingly small numbers of "real" > devices showing such behaviour, I also think it a bug for attaching a > disk to crash the kernel, even if the disk is broken. I see changes of > this sort as defense against broken disks if nothing else.
I agree. The kernel should not crash on such disks anymore — it is my understanding that this (or similar) crash is fixed by my patch that's been committed a month ago.. If you still have any such disks, and doing the multiply-or-divide trick would support them fully, then I'm all for making such a change. However, if such disks don't exist, I don't think it's fair to add untested code which might provoke other panics or data loss in some other paths. C.
