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

Xiao Guangrong
2012-03-08T07:51:12Z

On 03/08/2012 03:50 PM, Andrew Morton wrote:

> On Thu, 8 Mar 2012 18:41:05 +1100 Stephen Rothwell <sfr@canb.auug.org.au> wrote:
>
>> 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.
>
> Doh. The author reviewed that for me too!
>
> I'll drop it - please rework, retest and resend?

I am sorry, i will repost it!