[PATCH] cpuset: implement cpuset_mems_allowed

Provide a cpuset_mems_allowed() method, which the sys_migrate_pages() code
needed, to obtain the mems_allowed vector of a cpuset, and replaced the
workaround in sys_migrate_pages() to call this new method.

Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

include/linux/cpuset.h

@@ -18,7 +18,8 @@ extern int cpuset_init(void);
 extern void cpuset_init_smp(void);
 extern void cpuset_fork(struct task_struct *p);
 extern void cpuset_exit(struct task_struct *p);
-extern cpumask_t cpuset_cpus_allowed(const struct task_struct *p);
+extern cpumask_t cpuset_cpus_allowed(struct task_struct *p);
+extern nodemask_t cpuset_mems_allowed(struct task_struct *p);
 void cpuset_init_current_mems_allowed(void);
 void cpuset_update_task_memory_state(void);
 #define cpuset_nodes_subset_current_mems_allowed(nodes) \
@@ -50,6 +51,11 @@ static inline cpumask_t cpuset_cpus_allowed(struct task_struct *p)
 	return cpu_possible_map;
 }
 
+static inline nodemask_t cpuset_mems_allowed(struct task_struct *p)
+{
+	return node_possible_map;
+}
+
 static inline void cpuset_init_current_mems_allowed(void) {}
 static inline void cpuset_update_task_memory_state(void) {}
 #define cpuset_nodes_subset_current_mems_allowed(nodes) (1)

kernel/cpuset.c

@@ -1871,14 +1871,14 @@ void cpuset_exit(struct task_struct *tsk)
  * tasks cpuset.
  **/
 
-cpumask_t cpuset_cpus_allowed(const struct task_struct *tsk)
+cpumask_t cpuset_cpus_allowed(struct task_struct *tsk)
 {
 	cpumask_t mask;
 
 	down(&callback_sem);
-	task_lock((struct task_struct *)tsk);
+	task_lock(tsk);
 	guarantee_online_cpus(tsk->cpuset, &mask);
-	task_unlock((struct task_struct *)tsk);
+	task_unlock(tsk);
 	up(&callback_sem);
 
 	return mask;
@@ -1889,6 +1889,29 @@ void cpuset_init_current_mems_allowed(void)
 	current->mems_allowed = NODE_MASK_ALL;
 }
 
+/**
+ * cpuset_mems_allowed - return mems_allowed mask from a tasks cpuset.
+ * @tsk: pointer to task_struct from which to obtain cpuset->mems_allowed.
+ *
+ * Description: Returns the nodemask_t mems_allowed of the cpuset
+ * attached to the specified @tsk.  Guaranteed to return some non-empty
+ * subset of node_online_map, even if this means going outside the
+ * tasks cpuset.
+ **/
+
+nodemask_t cpuset_mems_allowed(struct task_struct *tsk)
+{
+	nodemask_t mask;
+
+	down(&callback_sem);
+	task_lock(tsk);
+	guarantee_online_mems(tsk->cpuset, &mask);
+	task_unlock(tsk);
+	up(&callback_sem);
+
+	return mask;
+}
+
 /**
  * cpuset_zonelist_valid_mems_allowed - check zonelist vs. curremt mems_allowed
  * @zl: the zonelist to be checked

mm/mempolicy.c

@@ -772,9 +772,6 @@ 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)