Hi Andrew,
On Fri, Mar 2, 2012 at 4:51 AM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote:
> On Thu, 1 Mar 2012 17:32:54 +0800
> Bob Liu <lliubbo@xxxxxxxxx> wrote:
>
>> +static int ksm_check_mm(struct mm_struct *mm, struct vm_area_struct *vma,
>> + unsigned long addr)
>> +{
>> + if (ksm_test_exit(mm))
>> + return 0;
>> + vma = find_vma(mm, addr);
>> + if (!vma || vma->vm_start > addr)
>> + return 0;
>> + if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma)
>> + return 0;
>> + return 1;
>> +}
>
> Can we please think of a suitable name for this check, other than
> "check"? IOW, give the function a meaningful name which describes what
> it is checking?
>
> And it's not checking the mm, is it? It is checking the address: to
> see whether it lies within a mergeable anon vma.
>
> So maybe
>
> --- a/mm/ksm.c~ksm-cleanup-introduce-ksm_check_mm-fix
> +++ a/mm/ksm.c
> @@ -375,17 +375,17 @@ static int break_ksm(struct vm_area_stru
> return (ret & VM_FAULT_OOM) ? -ENOMEM : 0;
> }
>
> -static int ksm_check_mm(struct mm_struct *mm, struct vm_area_struct *vma,
> - unsigned long addr)
> +static bool in_mergeable_anon_vma(struct mm_struct *mm,
> + struct vm_area_struct *vma, unsigned long addr)
> {
> if (ksm_test_exit(mm))
> - return 0;
> + return false;
> vma = find_vma(mm, addr);
> if (!vma || vma->vm_start > addr)
> - return 0;
> + return false;
> if (!(vma->vm_flags & VM_MERGEABLE) || !vma->anon_vma)
> - return 0;
> - return 1;
> + return false;
> + return true;
> }
>
> static void break_cow(struct rmap_item *rmap_item)
> @@ -401,7 +401,7 @@ static void break_cow(struct rmap_item *
> put_anon_vma(rmap_item->anon_vma);
>
> down_read(&mm->mmap_sem);
> - if (ksm_check_mm(mm, vma, addr))
> + if (in_mergeable_anon_vma(mm, vma, addr))
> break_ksm(vma, addr);
> up_read(&mm->mmap_sem);
> }
> @@ -428,7 +428,7 @@ static struct page *get_mergeable_page(s
> struct page *page;
>
> down_read(&mm->mmap_sem);
> - if (!ksm_check_mm(mm, vma, addr))
> + if (!in_mergeable_anon_vma(mm, vma, addr))
> goto out;
>
> page = follow_page(vma, addr, FOLL_GET);
> _
>
Yeah, It looks much better than mine, Thanks!
--
Regards,
--Bob
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