Re: kisskb: FAILED linux-next/m68k-allmodconfig/m68k-gcc8 Tue Jan 25, 18:24

[Geert Uytterhoeven]

Hi Arnd,

On Tue, Jan 25, 2022 at 1:49 PM Arnd Bergmann <arnd@xxxxxxxx> wrote:
> On Tue, Jan 25, 2022 at 9:47 AM Geert Uytterhoeven <geert@xxxxxxxxxxxxxx> wrote:
> > On Tue, Jan 25, 2022 at 8:31 AM <noreply@xxxxxxxxxxxxxx> wrote:
> > > FAILED linux-next/m68k-allmodconfig/m68k-gcc8 Tue Jan 25, 18:24
> > >
> > > http://kisskb.ellerman.id.au/kisskb/buildresult/14688953/
> > >
> > > Commit:   Add linux-next specific files for 20220125
> > >           d25ee88530253138d0b20d43511ca5acbda4e9f7
> > > Compiler: m68k-linux-gcc (GCC) 8.1.0 / GNU ld (GNU Binutils) 2.30
> > >
> > > Possible errors
> > > ---------------
> > >
> > > arch/m68k/include/asm/bitops.h:329:20: error: array subscript 2 is above array bounds of 'long unsigned int[1]' [-Werror=array-bounds]
> > > cc1: all warnings being treated as errors
> > > make[4]: *** [scripts/Makefile.build:289: drivers/net/ipa/ipa_mem.o] Error 1
> > > make[3]: *** [scripts/Makefile.build:572: drivers/net/ipa] Error 2
> > > make[2]: *** [scripts/Makefile.build:572: drivers/net] Error 2
> > > make[1]: *** [Makefile:1965: drivers] Error 2
> > > make: *** [Makefile:226: __sub-make] Error 2
> > >
> > > No warnings found in log.
> >
> > The code that causes this is drivers/net/ipa/ipa_mem.c:ipa_mem_valid():
> >
> >         DECLARE_BITMAP(regions, IPA_MEM_COUNT) = { };
> >         ...
> >         for_each_clear_bit(mem_id, regions, IPA_MEM_COUNT) {
> >                 if (ipa_mem_id_required(ipa, mem_id))
> >                         dev_err(dev, "required memory region %u missing\n",
> >                                 mem_id);
> >         }
> >
> > This only happens with gcc-8, not with gcc-9, so it might be a
> > compiler bug. I don't see anything wrong with c:ipa_mem_valid()
> > nor with m68k's find_first_zero_bit().
>
> I've seen problems with warnings like this when gcc only partially
> inlines one of the functions. Does it go away if you mark find_next_bit()
> and find_first_bit() as __always_inline?

Thanks for the suggestio, but it doesn't make a difference.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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