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From:   Arjun Roy <arjunroy@google.com>
Date:   Thu, 27 Feb 2020 09:13:38 -0800
Message-ID: <CAOFY-A0=AYDSdGq5tf7s6_kRjnDGLfLjCV9p+LdKbLwyw0J9nA@mail.gmail.com>
Subject: Re: linux-next: build failure after merge of the akpm tree
To:     Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     Stephen Rothwell <sfr@canb.auug.org.au>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux Next Mailing List <linux-next@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        David Miller <davem@davemloft.net>
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On Thu, Feb 27, 2020 at 1:03 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Stephen et al,
>
> On Thu, Feb 27, 2020 at 5:12 AM Stephen Rothwell <sfr@canb.auug.org.au> wrote:
> > After merging the akpm tree, today's linux-next build (sparc defconfig)
> > failed like this:
> >
> > In file included from include/linux/list.h:9:0,
> >                  from include/linux/smp.h:12,
> >                  from include/linux/kernel_stat.h:5,
> >                  from mm/memory.c:42:
> > mm/memory.c: In function 'insert_pages':
> > mm/memory.c:1523:41: error: implicit declaration of function 'pte_index'; did you mean 'page_index'? [-Werror=implicit-function-declaration]
> >    remaining_pages_total, PTRS_PER_PTE - pte_index(addr));
> >                                          ^
> > include/linux/kernel.h:842:40: note: in definition of macro '__typecheck'
> >    (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
> >                                         ^
> > include/linux/kernel.h:866:24: note: in expansion of macro '__safe_cmp'
> >   __builtin_choose_expr(__safe_cmp(x, y), \
> >                         ^~~~~~~~~~
> > include/linux/kernel.h:934:27: note: in expansion of macro '__careful_cmp'
> >  #define min_t(type, x, y) __careful_cmp((type)(x), (type)(y), <)
> >                            ^~~~~~~~~~~~~
> > mm/memory.c:1522:26: note: in expansion of macro 'min_t'
> >   pages_to_write_in_pmd = min_t(unsigned long,
> >                           ^~~~~
>
> Same issue on m68k, as per a report from kisskb.
>
> > Caused by patch
> >
> >   "mm/memory.c: add vm_insert_pages()"
> >
> > sparc32 does not implement pte_index at all :-(
>
> Seems like about only half of the architectures do.
>

:/ I begin to suspect the only sane way to make this work is to have a
per-arch header defined method, returning a bool saying whether
pte_index() is meaningful or not on that arch, and early on in
vm_insert_pages() if that bool returns true, to just call
vm_insert_page() in a loop.

-Arjun

> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-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