linux-kernel - Re: [PATCH v6 10/18] sh/tlb: Convert SH to generic mmu

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Date:   Wed, 4 Dec 2019 13:32:58 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Will Deacon <will.deacon@....com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Linux-Arch <linux-arch@...r.kernel.org>,
        Linux MM <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Russell King <linux@...linux.org.uk>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Rik van Riel <riel@...riel.com>,
        Yoshinori Sato <ysato@...rs.sourceforge.jp>,
        Rich Felker <dalias@...c.org>,
        Linux-sh list <linux-sh@...r.kernel.org>,
        Guenter Roeck <linux@...ck-us.net>
Subject: Re: [PATCH v6 10/18] sh/tlb: Convert SH to generic mmu_gather

Hoi Peter,

On Wed, Dec 4, 2019 at 11:48 AM Peter Zijlstra <peterz@...radead.org> 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@...radead.org> wrote:
> > > Generic mmu_gather provides everything SH needs (range tracking and
> > > cache coherency).
> > >
> > > Cc: Will Deacon <will.deacon@....com>
> > > Cc: "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
> > > Cc: Andrew Morton <akpm@...ux-foundation.org>
> > > Cc: Nick Piggin <npiggin@...il.com>
> > > Cc: Yoshinori Sato <ysato@...rs.sourceforge.jp>
> > > Cc: Rich Felker <dalias@...c.org>
> > > Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
> >
> > 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.

> > 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 ‘struct page *’ but argument is of type ‘pmd_t * {aka struct
<anonymous> *}’

> +       tlb_remove_page((tlb), (pmdp));                 \

likewise

>  } while (0);
>  #endif

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds