[PATCH] powerpc: is_hugepage_only_range() must account for both 4kB and 64kB slices

[Benjamin Herrenschmidt]

On Wed, 2009-01-14 at 13:09 -0600, Dave Kleikamp wrote:
> powerpc: is_hugepage_only_range() must account for both 4kB and 64kB slices
> 
> The subpage_prot syscall fails on second and subsequent calls for a given
> region, because is_hugepage_only_range() is mis-identifying the 4 kB
> slices when the process has a 64 kB page size.
> 
> Signed-off-by: Dave Kleikamp <shaggy at linux.vnet.ibm.com>
> Cc: Paul Mackerras <paulus at samba.org>
> Cc: Benjamin Herrenschmidt <benh at kernel.crashing.org>

Looks good. I'll put that in for .29

Cheers,
Ben.

> diff --git a/arch/powerpc/mm/slice.c b/arch/powerpc/mm/slice.c
> index db44e02..ba51948 100644
> --- a/arch/powerpc/mm/slice.c
> +++ b/arch/powerpc/mm/slice.c
> @@ -710,9 +710,18 @@ int is_hugepage_only_range(struct mm_struct *mm, unsigned long addr,
>  			   unsigned long len)
>  {
>  	struct slice_mask mask, available;
> +	unsigned int psize = mm->context.user_psize;
>  
>  	mask = slice_range_to_mask(addr, len);
> -	available = slice_mask_for_size(mm, mm->context.user_psize);
> +	available = slice_mask_for_size(mm, psize);
> +#ifdef CONFIG_PPC_64K_PAGES
> +	/* We need to account for 4k slices too */
> +	if (psize == MMU_PAGE_64K) {
> +		struct slice_mask compat_mask;
> +		compat_mask = slice_mask_for_size(mm, MMU_PAGE_4K);
> +		or_mask(available, compat_mask);
> +	}
> +#endif
>  
>  #if 0 /* too verbose */
>  	slice_dbg("is_hugepage_only_range(mm=%p, addr=%lx, len=%lx)\n",
>