[BUG] allmodconfig build error in next-20240108

[Paul E. McKenney]

On Tue, Jan 09, 2024 at 09:57:57AM +1100, Stephen Rothwell wrote:
> Hi Paul,
> 
> On Mon, 8 Jan 2024 13:33:36 -0800 "Paul E. McKenney" <paulmck at kernel.org> wrote:
> >
> > Recent -next trees get the following build error for allmodconfig builds:
> > 
> > ------------------------------------------------------------------------
> > 
> > drivers/gpu/drm/xe/xe_gt_pagefault.c: In function ‘xe_guc_pagefault_handler’:
> > ./include/linux/fortify-string.h:57:33: error: writing 16 bytes into a region of  size 0 [-Werror=stringop-overflow=]
> >    57 | #define __underlying_memcpy     __builtin_memcpy
> >       |                                 ^
> > ./include/linux/fortify-string.h:644:9: note: in expansion of macro ‘__underlying_memcpy’
> >   644 |         __underlying_##op(p, q, __fortify_size); \
> >       |         ^~~~~~~~~~~~~
> > ./include/linux/fortify-string.h:689:26: note: in expansion of macro ‘__fortify_memcpy_chk’
> >   689 | #define memcpy(p, q, s)  __fortify_memcpy_chk(p, q, s, \
> >       |                          ^~~~~~~~~~~~~~~~~~~~
> > drivers/gpu/drm/xe/xe_gt_pagefault.c:340:17: note: in expansion of macro ‘memcpy’
> >   340 |                 memcpy(pf_queue->data + pf_queue->tail, msg, len * sizeof(u32));
> >       |                 ^~~~~~
> > In file included from drivers/gpu/drm/xe/xe_device_types.h:17,
> >                  from drivers/gpu/drm/xe/xe_vm_types.h:16,
> >                  from drivers/gpu/drm/xe/xe_bo.h:13,
> >                  from drivers/gpu/drm/xe/xe_gt_pagefault.c:16:
> > drivers/gpu/drm/xe/xe_gt_types.h:102:25: note: at offset [1144, 265324] into destination object ‘tile’ of size 8
> >   102 |         struct xe_tile *tile;
> >       |
> 
> Which architecture?  What compiler and version?  Anything special in your build
> setup?  I do x86_64 allmodconfig builds all day with gcc v13.2 and I don't see
> this failure.

Good point!

I am using gcc version 11.3.1 20230605 (Red Hat 11.4.1-2) on x86_64.
I see the same behavior on gcc version 8.5.0, which for all I know might
be too old.

							Thanx, Paul