Re: [PATCH] drm/amd/display: Increase sanitizer frame larger than limit when compile testing with clang

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Jan 06, 2025 at 12:29:32PM -0500, Alex Deucher wrote:
> Applied.  Thanks!

Thanks, but I am still getting this error on Linus's current tree right
now, with this commit applied:

  CC [M]  drivers/gpu/drm/amd/amdgpu/../display/dc/dml2/display_mode_core.o
drivers/gpu/drm/amd/amdgpu/../display/dc/dml2/display_mode_core.c:6713:12: error: stack frame size (2056) exceeds limit (2048) in 'dml_core_mode_support' [-Werror,-Wframe-larger-than]
 6713 | dml_bool_t dml_core_mode_support(struct display_mode_lib_st *mode_lib)
      |            ^
1 error generated.


I think the issue is:

> > --- a/drivers/gpu/drm/amd/display/dc/dml2/Makefile
> > +++ b/drivers/gpu/drm/amd/display/dc/dml2/Makefile
> > @@ -29,7 +29,11 @@ dml2_rcflags := $(CC_FLAGS_NO_FPU)
> >
> >  ifneq ($(CONFIG_FRAME_WARN),0)
> >  ifeq ($(filter y,$(CONFIG_KASAN)$(CONFIG_KCSAN)),y)

I do not have CONFIG_KASAN or CONFIG_KCSAN enabled, but I do have:

> > +ifeq ($(CONFIG_CC_IS_CLANG)$(CONFIG_COMPILE_TEST),yy)

These two options enabled, and for some reason:
	CONFIG_FRAME_WARN=2048
as well.

Ah, 2048 is the default value, that's how.

So this warning triggers even without KASAN or KCSAN being enabled, is
that to be expected?  Is the stack really being used that much here?

I'll go bump FRAME_WARN up to get some local testing working again, but
odds are others are going to hit this if I am in my "normal" build
tests.

thanks,

greg k-h