Re: [PATCH v6 10/18] sh/tlb: Convert SH to generic mmu_gather

[Guenter Roeck]

On 12/4/19 4:32 AM, Geert Uytterhoeven wrote:
> Hoi Peter,
>
> On Wed, Dec 4, 2019 at 11:48 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> > On Tue, Dec 03, 2019 at 12:19:00PM +0100, Geert Uytterhoeven wrote:
> > > On Tue, Feb 19, 2019 at 11:35 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> > > > Generic mmu_gather provides everything SH needs (range tracking and
> > > > cache coherency).
> > > >
> > > > Cc: Will Deacon <will.deacon@xxxxxxx>
> > > > Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> > > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> > > > Cc: Nick Piggin <npiggin@xxxxxxxxx>
> > > > Cc: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
> > > > Cc: Rich Felker <dalias@xxxxxxxx>
> > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
> > >
> > > I got remote access to an SH7722-based Migo-R again, which spews a long
> > > sequence of BUGs during userspace startup.  I've bisected this to commit
> > > c5b27a889da92f4a ("sh/tlb: Convert SH to generic mmu_gather").
> >
> > Whoopsy.. also, is this really the first time anybody booted an SH
> > kernel in over a year ?!?
>
> Nah, but the v5.4-rc3 I booted recently on qemu -M r2d had
> CONFIG_PGTABLE_LEVELS=2, so it didn't show the problem.

Guess that explains why I do not see the problem with my qemu boots.
I use rts7751r2dplus_defconfig. Is it possible to reproduce the problem
with qemu ? I don't think so, but maybe I am missing something.

Guenter

> > > Do you have a clue?
> >
> > Does the below help?
>
> Unfortunately not.
>
> > diff --git a/arch/sh/include/asm/pgalloc.h b/arch/sh/include/asm/pgalloc.h
> > index 22d968bfe9bb..73a2c00de6c5 100644
> > --- a/arch/sh/include/asm/pgalloc.h
> > +++ b/arch/sh/include/asm/pgalloc.h
> > @@ -36,9 +36,8 @@ do {                                                  \
> >   #if CONFIG_PGTABLE_LEVELS > 2
> >   #define __pmd_free_tlb(tlb, pmdp, addr)                        \
> >   do {                                                   \
> > -       struct page *page = virt_to_page(pmdp);         \
> > -       pgtable_pmd_page_dtor(page);                    \
> > -       tlb_remove_page((tlb), page);                   \
> > +       pgtable_pmd_page_dtor(pmdp);                    \
>
> expected âstruct page *â but argument is of type âpmd_t * {aka struct
> <anonymous> *}â
>
> > +       tlb_remove_page((tlb), (pmdp));                 \
>
> likewise
>
> >   } while (0);
> >   #endif
>
> Gr{oetje,eeting}s,
>
>                          Geert