Subject: Re: [PATCH v1 03/27] powerpc/mm: don't BUG() in slice_mask_for_size()

From: "Aneesh Kumar K.V" <[email-masked]>
Date: Thu, 11 Apr 2019 11:11:39 +0530

Christophe Leroy <[email-masked]> writes:

> When no mask is found for the page size, WARN() and return NULL
> instead of BUG()ing.
>
> Signed-off-by: Christophe Leroy <[email-masked]>
> ---
>  arch/powerpc/mm/slice.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
> index aec91dbcdc0b..011d470ea340 100644
> --- a/arch/powerpc/mm/slice.c
> +++ b/arch/powerpc/mm/slice.c
> @@ -165,7 +165,8 @@ static struct slice_mask *slice_mask_for_size(struct mm_struct *mm, int psize)
>  	if (psize == MMU_PAGE_16G)
>  		return &mm->context.mask_16g;
>  #endif
> -	BUG();
> +	WARN_ON(true);
> +	return NULL;
>  }

Same here. There are not catching runtime errors. We should never find
that true. This is to catch mistakes during development changes. Switch
to VM_BUG_ON?

>  #elif defined(CONFIG_PPC_8xx)
>  static struct slice_mask *slice_mask_for_size(struct mm_struct *mm, int psize)
> @@ -178,7 +179,8 @@ static struct slice_mask *slice_mask_for_size(struct mm_struct *mm, int psize)
>  	if (psize == MMU_PAGE_8M)
>  		return &mm->context.mask_8m;
>  #endif
> -	BUG();
> +	WARN_ON(true);
> +	return NULL;
>  }
>  #else
>  #error "Must define the slice masks for page sizes supported by the platform"
> -- 
> 2.13.3