Messages in this thread | | | From | Atish Patra <> | Date | Fri, 26 May 2023 11:48:27 -0700 | Subject | Re: Bug report: kernel paniced when system hibernates |
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On Fri, May 26, 2023 at 8:22 AM Alexandre Ghiti <alexghiti@rivosinc.com> wrote: > > On Fri, May 26, 2023 at 5:17 PM Anup Patel <anup@brainfault.org> wrote: > > > > On Fri, May 26, 2023 at 8:42 PM Alexandre Ghiti <alex@ghiti.fr> wrote: > > > > > > > > > On 26/05/2023 16:59, Conor Dooley wrote: > > > > On Fri, May 26, 2023 at 03:14:33PM +0200, Alexandre Ghiti wrote: > > > >> Hi everyone, > > > >> > > > >> On Thu, May 25, 2023 at 11:24 PM Conor Dooley <conor@kernel.org> wrote: > > > >>> On Thu, May 25, 2023 at 01:06:04PM -0700, Atish Patra wrote: > > > >>>> On Thu, May 25, 2023 at 11:39 AM Conor Dooley <conor@kernel.org> wrote: > > > >>>>> On Thu, May 25, 2023 at 11:37:40AM -0700, Atish Patra wrote: > > > >>>>> > > > >>>>>> Any testing of hibernation still needs to revert the patch until we > > > >>>>>> have the proper fix. > > > >>>>> "the patch" is what exactly? I assume you don't mean depending on > > > >>>>> NONPORTABLE, since that is a Kconfig option. > > > >>>> Nope. Sorry I meant the commit > > > >>>> > > > >>>> 3335068 ("riscv: Use PUD/P4D/PGD pages for the linear mapping") > > > >>> Ah, if your SBI implementation is one of the affected ones, yeah. > > > >>> If not, you can just set NONPORTABLE :) > > > >> @Björn Töpel emitted the idea of excluding from the hibernation all > > > >> the memory nodes in the "/reserved-memory" node > > > >> (https://elixir.bootlin.com/linux/v6.4-rc1/source/Documentation/devicetree/bindings/reserved-memory/reserved-memory.yaml): > > > >> I have to admit that I don't see why it is not done by default by the > > > >> kernel. > > > > My understanding was that it was perfectly fine to use reserved memory > > > > nodes to fence off some memory to use in device drivers etc, which then > > > > may need to be saved/restored. > > > > > > > > > Agreed, but I would say that it's up to the driver then to take care of > > > that, see https://docs.kernel.org/driver-api/pm/notifiers.html > > > > I agree, it should be drivers responsibility to save/restore the dedicated > > reserved memory used by itself. > > > > Although, I think we should at least save/restore reserved memory > > regions having "reusable" property set. >
That would be certainly ideal. However, that piece of code has been present for ages (last commit was in 2008!). There may be a bunch of drivers written with this builtin assumption.
> Good point! I'll propose an RFC and gather feedback from the people in > charge of the hibernation process.
Hopefully, it's not too bad.
> > > > > Regards, > > Anup > > > > > > > > > > > >> Unless there is stuff in this node that needs to be "hibernated", I > > > >> think that would be a very good solution since we would not rely on > > > >> the name of the "internal" nodes of "/reserved-memory" (i.e. > > > >> "mmode_resv"). > > > >> > > > >> I'm digging into why it is not done by default, just wanted to have > > > >> your feedback before the week-end :)
-- Regards, Atish
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