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

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Jan 30, 2025 at 07:47:59AM +0100, Greg KH wrote:
> 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.

Ick, no, bumping CONFIG_FRAME_WARN=8192 doesn't fix this here either.
Any hints?

thanks,

greg k-h