am335x: 5.18.x: system stalling

[Yegor Yefremov]

Hi Arnd,

On Thu, May 26, 2022 at 4:16 PM Arnd Bergmann <arnd at arndb.de> wrote:
>
> On Thu, May 26, 2022 at 2:37 PM Yegor Yefremov
> <yegorslists at googlemail.com> wrote:
> > On Thu, May 26, 2022 at 10:19 AM Ard Biesheuvel <ardb at kernel.org> wrote:
> > >
> > > On Thu, 26 May 2022 at 08:20, Tony Lindgren <tony at atomide.com> wrote:
> > > >
> > > > * Yegor Yefremov <yegorslists at googlemail.com> [220526 05:45]:
> > > > > On Tue, May 24, 2022 at 4:19 PM Tony Lindgren <tony at atomide.com> wrote:
> > > > > > Maybe also try with CONFIG_MUSB_PIO_ONLY=y to see if it makes things
> > > > > > better or worse :)
> > > > >
> > > > > PIO is always the last resort :-) And now it proves it again. With
> > > > > PIO_ONLY the system doesn't stall.
> > > >
> > > > OK great :) So it has something to do with drivers/dma/ti/cppi41.c, or
> > > > with drivers/usb/musb/cppi_dma.c or whatever the dma for am335x here
> > > > is. Or maybe there's something using stack for buffers being passed to
> > > > dma again that breaks with vmap stack.
> > > >
> > >
> > > In order to confirm this theory, could you please try rebuilding your
> > > kernel with CONFIG_VMAP_STACK disabled, and leave everything else as
> > > before?
> >
> > I have disabled the CONFIG_VMAP_STACK option:
> >
> > # zcat /proc/config.gz | grep VMAP_STACK
> > CONFIG_HAVE_ARCH_VMAP_STACK=y
> > # CONFIG_VMAP_STACK is not set
> >
> > The system stalls.
>
> Ok, I guess that means we can stop looking for invalid DMA buffers
> on stacks. Out of the original commits you listed as possible causes,
> we can also rule out 23d9a9280efe ("ARM: 9177/1: disable vmap'ed
> stacks on suspend-capable SMP configs") and cafc0eab1689
> ("ARM: v7m: enable support for IRQ stacks"). It could still be
> 9c46929e7989 ("ARM: implement THREAD_INFO_IN_TASK for
> uniprocessor systems") and 5fe41793bc78 ("ARM: 9176/1: avoid
> literal references in inline assembly") or possibly the merge.
>
> Can you post the whole .config file somewhere for reference?
> In particular, do you have CONFIG_SMP, CONFIG_LD_IS_LLD
> or CURRENT_POINTER_IN_TPIDRURO set?

This is my config [1] and this is the system in question [2].

[1] https://github.com/visionsystemsgmbh/onrisc_br_bsp/blob/master/board/vscom/baltos/linux-experimental-config
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm/boot/dts/am335x-baltos-ir5221.dts?h=v5.18

Regards,
Yegor