Re: Linux 5.15

Geert Uytterhoeven
2021-11-01T08:13:44Z

Hi Günter.

On Mon, Nov 1, 2021 at 1:28 AM Guenter Roeck <linux@roeck-us.net> wrote:
> On Sun, Oct 31, 2021 at 02:09:07PM -0700, Linus Torvalds wrote:
> Building m68k:allmodconfig ... failed
> --------------
> Error log:
> In file included from include/linux/string.h:20,
> from include/linux/bitmap.h:10,
> from include/linux/cpumask.h:12,
> from include/linux/smp.h:13,
> from include/linux/lockdep.h:14,
> from include/linux/spinlock.h:63,
> from include/linux/mmzone.h:8,
> from include/linux/gfp.h:6,
> from include/linux/slab.h:15,
> from drivers/nvme/target/discovery.c:7:
> In function 'memcpy_and_pad',
> inlined from 'nvmet_execute_disc_identify' at drivers/nvme/target/discovery.c:268:2:
> arch/m68k/include/asm/string.h:72:25: error: '__builtin_memcpy' reading 8 bytes from a region of size 7
>
> Another instance of the same problem:
>
> In function 'memcpy_and_pad',
> inlined from 'nvmet_execute_identify_ctrl' at drivers/nvme/target/admin-cmd.c:372:2:
> arch/m68k/include/asm/string.h:72:25: error: '__builtin_memcpy' reading 8 bytes from a region of size 7
>
> This is seen with gcc 11.1 and 11.2. gcc 10.3 builds fine.
> The code in question is
>
> memcpy_and_pad(id->fr, sizeof(id->fr),
> UTS_RELEASE, strlen(UTS_RELEASE), ' ');
>
> and UTS_RELEASE is "5.15.0". I have no idea what might be wrong with the code.

Me neither. That warning (now error) has been seen with all point
releases (i.e. strlen(UTS_RELEASE) < 8) since v5.0.

> Does anyone have an idea ?

We had a discussion in
https://lore.kernel.org/all/CAMuHMdX365qmWiii=gQLADpW49EMkdDrVJDPWNBpAZuZM0WQFQ@mail.gmail.com
but without any definitive conclusion.

> Do I need to revert to gcc 10.3 for m68k ?

I'm not sure that might help, as the issue has been seen with
e.g. 8.1.0 and 8.2.0, too, with a slightly different message:
warning: ‘__builtin_memcpy’ forming offset 8 is out of the bounds [0,
7] [-Warray-bounds]

Any suggestions? Thanks!

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