1 files changed, 93 insertions, 1 deletions

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 9cc6d962831d..20d5ad39fa41 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -615,11 +615,41 @@ long do_get_mempolicy(int *policy, nodemask_t *nmask,
 }
 
 /*
+ * For now migrate_pages simply swaps out the pages from nodes that are in
+ * the source set but not in the target set. In the future, we would
+ * want a function that moves pages between the two nodesets in such
+ * a way as to preserve the physical layout as much as possible.
+ *
+ * Returns the number of page that could not be moved.
+ */
+int do_migrate_pages(struct mm_struct *mm,
+        const nodemask_t *from_nodes, const nodemask_t *to_nodes, int flags)
+{
+        LIST_HEAD(pagelist);
+        int count = 0;
+        nodemask_t nodes;
+
+        nodes_andnot(nodes, *from_nodes, *to_nodes);
+        nodes_complement(nodes, nodes);
+
+        down_read(&mm->mmap_sem);
+        check_range(mm, mm->mmap->vm_start, TASK_SIZE, &nodes,
+                        flags | MPOL_MF_DISCONTIG_OK, &pagelist);
+        if (!list_empty(&pagelist)) {
+                migrate_pages(&pagelist, NULL);
+                if (!list_empty(&pagelist))
+                        count = putback_lru_pages(&pagelist);
+        }
+        up_read(&mm->mmap_sem);
+        return count;
+}
+
+/*
  * User space interface with variable sized bitmaps for nodelists.
  */
 
 /* Copy a node mask from user space. */
-static int get_nodes(nodemask_t *nodes, unsigned long __user *nmask,
+static int get_nodes(nodemask_t *nodes, const unsigned long __user *nmask,
                      unsigned long maxnode)
 {
         unsigned long k;
@@ -708,6 +738,68 @@ asmlinkage long sys_set_mempolicy(int mode, unsigned long __user *nmask,
         return do_set_mempolicy(mode, &nodes);
 }
 
+/* Macro needed until Paul implements this function in kernel/cpusets.c */
+#define cpuset_mems_allowed(task) node_online_map
+
+asmlinkage long sys_migrate_pages(pid_t pid, unsigned long maxnode,
+                const unsigned long __user *old_nodes,
+                const unsigned long __user *new_nodes)
+{
+        struct mm_struct *mm;
+        struct task_struct *task;
+        nodemask_t old;
+        nodemask_t new;
+        nodemask_t task_nodes;
+        int err;
+
+        err = get_nodes(&old, old_nodes, maxnode);
+        if (err)
+                return err;
+
+        err = get_nodes(&new, new_nodes, maxnode);
+        if (err)
+                return err;
+
+        /* Find the mm_struct */
+        read_lock(&tasklist_lock);
+        task = pid ? find_task_by_pid(pid) : current;
+        if (!task) {
+                read_unlock(&tasklist_lock);
+                return -ESRCH;
+        }
+        mm = get_task_mm(task);
+        read_unlock(&tasklist_lock);
+
+        if (!mm)
+                return -EINVAL;
+
+        /*
+         * Check if this process has the right to modify the specified
+         * process. The right exists if the process has administrative
+         * capabilities, superuser priviledges or the same
+         * userid as the target process.
+         */
+        if ((current->euid != task->suid) && (current->euid != task->uid) &&
+            (current->uid != task->suid) && (current->uid != task->uid) &&
+            !capable(CAP_SYS_ADMIN)) {
+                err = -EPERM;
+                goto out;
+        }
+
+        task_nodes = cpuset_mems_allowed(task);
+        /* Is the user allowed to access the target nodes? */
+        if (!nodes_subset(new, task_nodes) && !capable(CAP_SYS_ADMIN)) {
+                err = -EPERM;
+                goto out;
+        }
+
+        err = do_migrate_pages(mm, &old, &new, MPOL_MF_MOVE);
+out:
+        mmput(mm);
+        return err;
+}
+
+
 /* Retrieve NUMA policy */
 asmlinkage long sys_get_mempolicy(int __user *policy,
                                 unsigned long __user *nmask,