Re: + mm-revert-thp-make-madv_hugepage-check-for-mm-def_flags.patch added to -mm tree

[Peter Zijlstra <peterz@infradead.org>]

On Wed, Feb 26, 2014 at 04:31:44PM +0100, Oleg Nesterov wrote:
> --- x/arch/s390/mm/pgtable.c
> +++ x/arch/s390/mm/pgtable.c
> @@ -1084,7 +1084,6 @@ static inline void thp_split_mm(struct m
>  		vma->vm_flags &= ~VM_HUGEPAGE;
>  		vma->vm_flags |= VM_NOHUGEPAGE;
>  	}
> -	mm->def_flags |= VM_NOHUGEPAGE;
>  }
>  #else
>  static inline void thp_split_mm(struct mm_struct *mm)
> --- x/mm/huge_memory.c
> +++ x/mm/huge_memory.c
> @@ -1968,8 +1968,6 @@ out:
>  int hugepage_madvise(struct vm_area_struct *vma,
>  		     unsigned long *vm_flags, int advice)
>  {
> -	struct mm_struct *mm = vma->vm_mm;
> -
>  	switch (advice) {
>  	case MADV_HUGEPAGE:
>  		/*
> @@ -1977,8 +1975,12 @@ int hugepage_madvise(struct vm_area_stru
>  		 */
>  		if (*vm_flags & (VM_HUGEPAGE | VM_NO_THP))
>  			return -EINVAL;
> -		if (mm->def_flags & VM_NOHUGEPAGE)
> +
> +#ifdef CONFIG_S390

Do we want a comment here, explaining why s390 is special again?

> +		if (mm_has_pgste(vma->vm_mm))
>  			return -EINVAL;
> +#endif
> +
>  		*vm_flags &= ~VM_NOHUGEPAGE;
>  		*vm_flags |= VM_HUGEPAGE;
>  		/*
>