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SubjectRe: [PATCH 1/1] pagemap clear_refs: modify to specify anon or mapped vma clearing
On Thu, Jul 23, 2009 at 08:57:22PM -0700, Moussa A. Ba wrote:
>
> Signed-off-by: Jared E. Hulbert <jaredeh@gmail.com>
> Signed-off-by: Moussa Ba <moussa.a.ba@gmail.com>
> --- a/fs/proc/task_mmu.c 2009-07-21 14:30:01.000000000 -0700
> +++ b/fs/proc/task_mmu.c 2009-07-21 14:32:56.000000000 -0700
> @@ -461,6 +461,33 @@
> cond_resched();
> return 0;
> }
> +static void walk_vma_area(struct mm_walk *this_walk, struct
> vm_area_struct *vma,
> + int type)
> +{
> + switch (type) {
> + /* Clear Anon VMAs only */
> + case 1:
> + if (!is_vm_hugetlb_page(vma) && !vma->vm_file)
> + walk_page_range(vma->vm_start,
> + vma->vm_end,
> + this_walk);
> + break;
> + /* Clear Mapped VMAs only */
> + case 2:
> + if (!is_vm_hugetlb_page(vma) && vma->vm_file)
> + walk_page_range(vma->vm_start,
> + vma->vm_end,
> + this_walk);
> + break;
> + /* Clear All VMAs */
> + default:
> + if (!is_vm_hugetlb_page(vma))
> + walk_page_range(vma->vm_start,
> + vma->vm_end,
> + this_walk);
> + break;
> + }
> +}
>


First, can you make these plain numbers as macros or enum types?

Second, I believe the above code can be simiplified, how about below?

{
if (!is_vm_hugetlb_page(vma)) {
if (type == 1 && vma->vm_file)
return;
if (type == 2 && !vma->vm_file)
return;
walk_page_range(vma->vm_start, vma->end, this_walk);
}
}



> static ssize_t clear_refs_write(struct file *file, const char __user *
> buf,
> size_t count, loff_t * ppos)
> @@ -469,13 +496,15 @@
> char buffer[PROC_NUMBUF], *end;
> struct mm_struct *mm;
> struct vm_area_struct *vma;
> + int type;
>
> memset(buffer, 0, sizeof(buffer));
> if (count > sizeof(buffer) - 1)
> count = sizeof(buffer) - 1;
> if (copy_from_user(buffer, buf, count))
> return -EFAULT;
> - if (!simple_strtol(buffer, &end, 0))
> + type = simple_strtol(buffer, &end, 0);
> + if (!type)
> return -EINVAL;
> if (*end == '\n')
> end++;
> @@ -491,9 +520,7 @@
> down_read(&mm->mmap_sem);
> for (vma = mm->mmap; vma; vma = vma->vm_next) {
> clear_refs_walk.private = vma;
> - if (!is_vm_hugetlb_page(vma))
> - walk_page_range(vma->vm_start, vma->vm_end,
> - &clear_refs_walk);
> + walk_vma_area(&clear_refs_walk, vma, type);
> }
> flush_tlb_mm(mm);
> up_read(&mm->mmap_sem);
> --
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