Subject: Re: [mainline][Oops][bisected 2ba3e6 ] 5.7.0 boot fails with kernel panic on powerpc

From: Abdul Haleem <[email-masked]>
Date: Thu, 04 Jun 2020 11:27:58 +0530

On Wed, 2020-06-03 at 15:32 +0200, Joerg Roedel wrote:
> On Wed, Jun 03, 2020 at 04:20:57PM +0530, Abdul Haleem wrote:
> > @Joerg, Could you please have a look?
> 
> Can you please try the attached patch?

Thanks Joerg, The given patch fixes the boot problem.

Please add Reported-by in fix commit.

Reported-by: Abdul Haleem <[email-masked]>

> 
> diff --git a/include/asm-generic/5level-fixup.h b/include/asm-generic/5level-fixup.h
> index 58046ddc08d0..afbab31fbd7e 100644
> --- a/include/asm-generic/5level-fixup.h
> +++ b/include/asm-generic/5level-fixup.h
> @@ -17,6 +17,11 @@
>  	((unlikely(pgd_none(*(p4d))) && __pud_alloc(mm, p4d, address)) ? \
>  		NULL : pud_offset(p4d, address))
> 
> +#define pud_alloc_track(mm, p4d, address, mask)					\
> +	((unlikely(pgd_none(*(p4d))) &&						\
> +	  (__pud_alloc(mm, p4d, address) || ({*(mask)|=PGTBL_P4D_MODIFIED;0;})))?	\
> +	  NULL : pud_offset(p4d, address))
> +
>  #define p4d_alloc(mm, pgd, address)		(pgd)
>  #define p4d_alloc_track(mm, pgd, address, mask)	(pgd)
>  #define p4d_offset(pgd, start)			(pgd)
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 7e07f4f490cb..d46bf03b804f 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2088,35 +2088,35 @@ static inline pud_t *pud_alloc(struct mm_struct *mm, p4d_t *p4d,
>  		NULL : pud_offset(p4d, address);
>  }
> 
> -static inline p4d_t *p4d_alloc_track(struct mm_struct *mm, pgd_t *pgd,
> +static inline pud_t *pud_alloc_track(struct mm_struct *mm, p4d_t *p4d,
>  				     unsigned long address,
>  				     pgtbl_mod_mask *mod_mask)
> -
>  {
> -	if (unlikely(pgd_none(*pgd))) {
> -		if (__p4d_alloc(mm, pgd, address))
> +	if (unlikely(p4d_none(*p4d))) {
> +		if (__pud_alloc(mm, p4d, address))
>  			return NULL;
> -		*mod_mask |= PGTBL_PGD_MODIFIED;
> +		*mod_mask |= PGTBL_P4D_MODIFIED;
>  	}
> 
> -	return p4d_offset(pgd, address);
> +	return pud_offset(p4d, address);
>  }
> 
> -#endif /* !__ARCH_HAS_5LEVEL_HACK */
> -
> -static inline pud_t *pud_alloc_track(struct mm_struct *mm, p4d_t *p4d,
> +static inline p4d_t *p4d_alloc_track(struct mm_struct *mm, pgd_t *pgd,
>  				     unsigned long address,
>  				     pgtbl_mod_mask *mod_mask)
> +
>  {
> -	if (unlikely(p4d_none(*p4d))) {
> -		if (__pud_alloc(mm, p4d, address))
> +	if (unlikely(pgd_none(*pgd))) {
> +		if (__p4d_alloc(mm, pgd, address))
>  			return NULL;
> -		*mod_mask |= PGTBL_P4D_MODIFIED;
> +		*mod_mask |= PGTBL_PGD_MODIFIED;
>  	}
> 
> -	return pud_offset(p4d, address);
> +	return p4d_offset(pgd, address);
>  }
> 
> +#endif /* !__ARCH_HAS_5LEVEL_HACK */
> +
>  static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
>  {
>  	return (unlikely(pud_none(*pud)) && __pmd_alloc(mm, pud, address))?

-- 
Regard's

Abdul Haleem
IBM Linux Technology Centre