Hi,

Lennart asked for madvise(WILLNEED) to work on anonymous pages, he plans
to use this to pre-fault pages. He currently uses: mlock/munlock for
this purpose.

[ compile tested only ]

Signed-off-by: Peter Zijlstra <[EMAIL PROTECTED]>
---
diff --git a/mm/madvise.c b/mm/madvise.c
index 93ee375..eff60ce 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -100,6 +100,24 @@ out:
        return error;
 }
 
+static long madvice_willneed_anon(struct vm_area_struct *vma,
+                                 struct vm_area_struct **prev,
+                                 unsigned long start, unsigned long end)
+{
+       int ret, len;
+
+       *prev = vma;
+       if (end > vma->vm_end)
+               end = vma->vm_end;
+
+       len = end - start;
+       ret = get_user_pages(current, current->mm, start, len,
+                       0, 0, NULL, NULL);
+       if (ret < 0)
+               return ret;
+       return ret == len ? 0 : -1;
+}
+
 /*
  * Schedule all required I/O operations.  Do not wait for completion.
  */
@@ -110,7 +128,7 @@ static long madvise_willneed(struct vm_area_struct * vma,
        struct file *file = vma->vm_file;
 
        if (!file)
-               return -EBADF;
+               return madvice_willneed_anon(vma, prev, start, end);
 
        if (file->f_mapping->a_ops->get_xip_page) {
                /* no bad return value, but ignore advice */


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