On Thu, 8 Mar 2012 18:41:05 +1100 Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> wrote:
> Hi Andrew,
>
> On Wed, 7 Mar 2012 23:32:20 -0800 Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> 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.
Doh. The author reviewed that for me too!
I'll drop it - please rework, retest and resend?
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