Re: linux-next: manual merge of the akpm tree with Linus' tree

Stephen Rothwell
2012-03-08T07:41:17Z

[-- Attachment #1: Type: text/plain, Size: 2073 bytes --]

Hi Andrew,

On Wed, 7 Mar 2012 23:32:20 -0800 Andrew Morton <akpm@linux-foundation.org> wrote:
>
> Actually they're different. I reworked the earlier patch as below.

OK. But some comments.

> diff -puN arch/x86/mm/hugetlbpage.c~hugetlb-drop-prev_vma-in-hugetlb_get_unmapped_area_topdown arch/x86/mm/hugetlbpage.c
> --- a/arch/x86/mm/hugetlbpage.c~hugetlb-drop-prev_vma-in-hugetlb_get_unmapped_area_topdown
> +++ a/arch/x86/mm/hugetlbpage.c
> @@ -308,7 +308,7 @@ static unsigned long hugetlb_get_unmappe
> {
> struct hstate *h = hstate_file(file);
> struct mm_struct *mm = current->mm;
> - struct vm_area_struct *vma, *prev_vma;
> + struct vm_area_struct *vma;

You still remove prev_vma ...

> unsigned long base = mm->mmap_base, addr = addr0;
> unsigned long largest_hole = mm->cached_hole_size;
> int first_time = 1;
> @@ -334,25 +334,16 @@ try_again:
> * i.e. return with success:
> */
> vma = find_vma(mm, addr);
> - if (!vma)
> - return addr;
> -
> - /*
> - * new region fits between prev_vma->vm_end and
> - * vma->vm_start, use it:
> - */
> - prev_vma = vma->vm_prev;
> - if (addr + len <= vma->vm_start &&
> - (!prev_vma || (addr >= prev_vma->vm_end))) {
> + if (vma)
> + prev_vma = vma->vm_prev;

But then assign to it ...

> + if (!vma || addr + len <= vma->vm_start) {
> /* remember the address as a hint for next time */
> mm->cached_hole_size = largest_hole;
> return (mm->free_area_cache = addr);
> - } else {
> + } else if (mm->free_area_cache == vma->vm_end) {
> /* pull free_area_cache down to the first hole */
> - if (mm->free_area_cache == vma->vm_end) {
> - mm->free_area_cache = vma->vm_start;
> - mm->cached_hole_size = largest_hole;
> - }
> + mm->free_area_cache = vma->vm_start;
> + mm->cached_hole_size = largest_hole;
> }
>
> /* remember the largest hole we saw so far */

But it never gets used.

--
Cheers,
Stephen Rothwell sfr@canb.auug.org.au

[-- Attachment #2: Type: application/pgp-signature, Size: 836 bytes --]