mm: don't vmalloc a huge page_to_node array for do_pages_stat()

do_pages_stat() does not need any page_to_node entry for real.  Just pass
the pointers to the user-space page address array and to the user-space
status array, and have do_pages_stat() traverse the former and fill the
latter directly.

Signed-off-by: Brice Goglin <Brice.Goglin@inria.fr>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/migrate.c b/mm/migrate.c
index f233519..a4c2908 100644 (file)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -906,25 +906,33 @@ set_status:
 }
 
 /*
- * Determine the nodes of a list of pages. The addr in the pm array
- * must have been set to the virtual address of which we want to determine
- * the node number.
+ * Determine the nodes of an array of pages and store it in an array of status.
  */
-static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm)
+static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
+                        const void __user * __user *pages,
+                        int __user *status)
 {
+       unsigned long i;
+       int err;
+
        down_read(&mm->mmap_sem);
 
-       for ( ; pm->node != MAX_NUMNODES; pm++) {
+       for (i = 0; i < nr_pages; i++) {
+               const void __user *p;
+               unsigned long addr;
                struct vm_area_struct *vma;
                struct page *page;
-               int err;
 
                err = -EFAULT;
-               vma = find_vma(mm, pm->addr);
+               if (get_user(p, pages+i))
+                       goto out;
+               addr = (unsigned long) p;
+
+               vma = find_vma(mm, addr);
                if (!vma)
                        goto set_status;
 
-               page = follow_page(vma, pm->addr, 0);
+               page = follow_page(vma, addr, 0);
 
                err = PTR_ERR(page);
                if (IS_ERR(page))
@@ -937,11 +945,13 @@ static int do_pages_stat(struct mm_struct *mm, struct page_to_node *pm)
 
                err = page_to_nid(page);
 set_status:
-               pm->status = err;
+               put_user(err, status+i);
        }
+       err = 0;
 
+out:
        up_read(&mm->mmap_sem);
-       return 0;
+       return err;
 }
 
 /*
@@ -997,6 +1007,10 @@ asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages,
        if (err)
                goto out2;
 
+       if (!nodes) {
+               err = do_pages_stat(mm, nr_pages, pages, status);
+               goto out2;
+       }
 
        task_nodes = cpuset_mems_allowed(task);
 
@@ -1045,11 +1059,7 @@ asmlinkage long sys_move_pages(pid_t pid, unsigned long nr_pages,
        /* End marker */
        pm[nr_pages].node = MAX_NUMNODES;
 
-       if (nodes)
-               err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL);
-       else
-               err = do_pages_stat(mm, pm);
-
+       err = do_move_pages(mm, pm, flags & MPOL_MF_MOVE_ALL);
        if (err >= 0)
                /* Return status information */
                for (i = 0; i < nr_pages; i++)