[PATCH] splice: add direct fd <-> fd splicing support

[linux-2.6-omap-h63xx.git] / kernel / cpuset.c

diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 2523a4b6a8c646040804f89f319cb7d88186df50..72248d1b9e3f7a18198796ad1134c9abb2fd4b4e 100644 (file)
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -833,6 +833,55 @@ static int update_cpumask(struct cpuset *cs, char *buf)
        return 0;
 }
 
+/*
+ * cpuset_migrate_mm
+ *
+ *    Migrate memory region from one set of nodes to another.
+ *
+ *    Temporarilly set tasks mems_allowed to target nodes of migration,
+ *    so that the migration code can allocate pages on these nodes.
+ *
+ *    Call holding manage_mutex, so our current->cpuset won't change
+ *    during this call, as manage_mutex holds off any attach_task()
+ *    calls.  Therefore we don't need to take task_lock around the
+ *    call to guarantee_online_mems(), as we know no one is changing
+ *    our tasks cpuset.
+ *
+ *    Hold callback_mutex around the two modifications of our tasks
+ *    mems_allowed to synchronize with cpuset_mems_allowed().
+ *
+ *    While the mm_struct we are migrating is typically from some
+ *    other task, the task_struct mems_allowed that we are hacking
+ *    is for our current task, which must allocate new pages for that
+ *    migrating memory region.
+ *
+ *    We call cpuset_update_task_memory_state() before hacking
+ *    our tasks mems_allowed, so that we are assured of being in
+ *    sync with our tasks cpuset, and in particular, callbacks to
+ *    cpuset_update_task_memory_state() from nested page allocations
+ *    won't see any mismatch of our cpuset and task mems_generation
+ *    values, so won't overwrite our hacked tasks mems_allowed
+ *    nodemask.
+ */
+
+static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
+                                                       const nodemask_t *to)
+{
+       struct task_struct *tsk = current;
+
+       cpuset_update_task_memory_state();
+
+       mutex_lock(&callback_mutex);
+       tsk->mems_allowed = *to;
+       mutex_unlock(&callback_mutex);
+
+       do_migrate_pages(mm, from, to, MPOL_MF_MOVE_ALL);
+
+       mutex_lock(&callback_mutex);
+       guarantee_online_mems(tsk->cpuset, &tsk->mems_allowed);
+       mutex_unlock(&callback_mutex);
+}
+
 /*
  * Handle user request to change the 'mems' memory placement
  * of a cpuset.  Needs to validate the request, update the
@@ -945,10 +994,8 @@ static int update_nodemask(struct cpuset *cs, char *buf)
                struct mm_struct *mm = mmarray[i];
 
                mpol_rebind_mm(mm, &cs->mems_allowed);
-               if (migrate) {
-                       do_migrate_pages(mm, &oldmem, &cs->mems_allowed,
-                                                       MPOL_MF_MOVE_ALL);
-               }
+               if (migrate)
+                       cpuset_migrate_mm(mm, &oldmem, &cs->mems_allowed);
                mmput(mm);
        }
 
@@ -1183,11 +1230,11 @@ static int attach_task(struct cpuset *cs, char *pidbuf, char **ppathbuf)
        mm = get_task_mm(tsk);
        if (mm) {
                mpol_rebind_mm(mm, &to);
+               if (is_memory_migrate(cs))
+                       cpuset_migrate_mm(mm, &from, &to);
                mmput(mm);
        }
 
-       if (is_memory_migrate(cs))
-               do_migrate_pages(tsk->mm, &from, &to, MPOL_MF_MOVE_ALL);
        put_task_struct(tsk);
        synchronize_rcu();
        if (atomic_dec_and_test(&oldcs->count))