On Mon, Oct 9, 2023 at 11:30 AM Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: > > Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> writes: > > > On Mon, Oct 2, 2023 at 2:18 PM Joel Fernandes <joel@xxxxxxxxxxxxxxxxx> wrote: > > [..] > >> > > Such freezing is already being done if kernel supports KEXEC_JUMP and > >> > > kexec_image->preserve_context is true. However, doing it if either of these are > >> > > not true prevents crashes/races. > >> > > >> > The KEXEC_JUMP case is something else entirely. It is supposed to work > >> > like suspend to RAM. Maybe reboot should as well, but I am > >> > uncomfortable making a generic device fix kexec specific. > >> > >> I see your point of view. I think regular reboot should also be fixed > >> to avoid similar crash possibilities. I am happy to make a change for > >> that similar to this patch if we want to proceed that way. > >> > >> Thoughts? > > > > Just checking how we want to proceed, is the consensus that we should > > prevent kernel crashes without relying on userspace stopping all > > processes? Should we fix regular reboot syscall as well and not just > > kexec reboot? > > It just occurred to me there is something very fishy about all of this. > > What userspace do you have using kexec (not kexec on panic) that doesn't > preform the same userspace shutdown as a normal reboot? > > Quite frankly such a userspace is buggy, and arguably that is where you > should start fixing things. It is a simple unit test that tests kexec support by kexec-rebooting the kernel. I don't think SIGSTOP/SIGKILL'ing during kexec-reboot is ideal because in a real panic-on-kexec type crash, that may not happen and so does not emulate the real world that well. I think we want the kexec-reboot to do a *reboot* without crashing the kernel while doing so. Ricardo/Steve can chime on what they feel as well. > That way you can get the orderly shutdown > of userspace daemons/services along with an orderly shutdown of > everything the kernel is responsible for. Fixing in userspace is an option but people are not happy that the kernel can crash like that. > At the kernel level a kexec reboot and a normal reboot have been > deliberately kept as close as possible. Which is why I say we should > fix it in reboot. You mean fix it in userspace? thanks, - Joel _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
