powerpc: Fix hugetlb with CONFIG_PPC_MM_SLICES=y

Commit 41151e77a4 ("powerpc: Hugetlb for BookE") added some
#ifdef CONFIG_MM_SLICES conditionals to hugetlb_get_unmapped_area()
and vma_mmu_pagesize().  Unfortunately this is not the correct config
symbol; it should be CONFIG_PPC_MM_SLICES.  The result is that
attempting to use hugetlbfs on 64-bit Power server processors results
in an infinite stack recursion between get_unmapped_area() and
hugetlb_get_unmapped_area().

This fixes it by changing the #ifdef to use CONFIG_PPC_MM_SLICES
in those functions and also in book3e_hugetlb_preload().

Signed-off-by: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/mm/hugetlbpage-book3e.c |    2 +-
 arch/powerpc/mm/hugetlbpage.c        |    4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

On Sep 21, 2011, at 12:58 AM, Paul Mackerras wrote:

> Commit 41151e77a4 ("powerpc: Hugetlb for BookE") added some
> #ifdef CONFIG_MM_SLICES conditionals to hugetlb_get_unmapped_area()
> and vma_mmu_pagesize().  Unfortunately this is not the correct config
> symbol; it should be CONFIG_PPC_MM_SLICES.  The result is that
> attempting to use hugetlbfs on 64-bit Power server processors results
> in an infinite stack recursion between get_unmapped_area() and
> hugetlb_get_unmapped_area().
> 
> This fixes it by changing the #ifdef to use CONFIG_PPC_MM_SLICES
> in those functions and also in book3e_hugetlb_preload().
> 
> Signed-off-by: Paul Mackerras <paulus@samba.org>

Paul, Ben,

ACK since it looks like Ben has picked this up already..... but FYI I have a different version of this fix in my tree.  The get_unmapped_area() shouldn't be there  *at all*  - we can just use the generic code if we don't have slices.  So instead the whole hugetlb_get_unmapped_area function should be wrapped in PPC_MM_SLICES.  This is crufty debug stuff that I missed yanking out when I pushed the patch, my apologies.

I'll just submit a followup patch to fix this.

Cheers,
B

> ---
> arch/powerpc/mm/hugetlbpage-book3e.c |    2 +-
> arch/powerpc/mm/hugetlbpage.c        |    4 ++--
> 2 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/mm/hugetlbpage-book3e.c b/arch/powerpc/mm/hugetlbpage-book3e.c
> index 1295b7c..343ad0b 100644
> --- a/arch/powerpc/mm/hugetlbpage-book3e.c
> +++ b/arch/powerpc/mm/hugetlbpage-book3e.c
> @@ -52,7 +52,7 @@ void book3e_hugetlb_preload(struct mm_struct *mm, unsigned long ea, pte_t pte)
> 	if (unlikely(is_kernel_addr(ea)))
> 		return;
> 
> -#ifdef CONFIG_MM_SLICES
> +#ifdef CONFIG_PPC_MM_SLICES
> 	psize = mmu_get_tsize(get_slice_psize(mm, ea));
> 	tsize = mmu_get_psize(psize);
> 	shift = mmu_psize_defs[psize].shift;
> diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
> index 3a5f59d..48b65be 100644
> --- a/arch/powerpc/mm/hugetlbpage.c
> +++ b/arch/powerpc/mm/hugetlbpage.c
> @@ -690,7 +690,7 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
> 					unsigned long len, unsigned long pgoff,
> 					unsigned long flags)
> {
> -#ifdef CONFIG_MM_SLICES
> +#ifdef CONFIG_PPC_MM_SLICES
> 	struct hstate *hstate = hstate_file(file);
> 	int mmu_psize = shift_to_mmu_psize(huge_page_shift(hstate));
> 
> @@ -702,7 +702,7 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
> 
> unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
> {
> -#ifdef CONFIG_MM_SLICES
> +#ifdef CONFIG_PPC_MM_SLICES
> 	unsigned int psize = get_slice_psize(vma->vm_mm, vma->vm_start);
> 
> 	return 1UL << mmu_psize_to_shift(psize);
> -- 
> 1.7.5.4