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-rw-r--r--kernel/cpuset.c87
1 files changed, 70 insertions, 17 deletions
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 794af5024c2f..cc0395d7eba1 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -2040,6 +2040,73 @@ out:
return err;
}
+#if defined(CONFIG_HOTPLUG_CPU) || defined(CONFIG_MEMORY_HOTPLUG)
+/*
+ * If common_cpu_mem_hotplug_unplug(), below, unplugs any CPUs
+ * or memory nodes, we need to walk over the cpuset hierarchy,
+ * removing that CPU or node from all cpusets. If this removes the
+ * last CPU or node from a cpuset, then the guarantee_online_cpus()
+ * or guarantee_online_mems() code will use that emptied cpusets
+ * parent online CPUs or nodes. Cpusets that were already empty of
+ * CPUs or nodes are left empty.
+ *
+ * This routine is intentionally inefficient in a couple of regards.
+ * It will check all cpusets in a subtree even if the top cpuset of
+ * the subtree has no offline CPUs or nodes. It checks both CPUs and
+ * nodes, even though the caller could have been coded to know that
+ * only one of CPUs or nodes needed to be checked on a given call.
+ * This was done to minimize text size rather than cpu cycles.
+ *
+ * Call with both manage_mutex and callback_mutex held.
+ *
+ * Recursive, on depth of cpuset subtree.
+ */
+
+static void guarantee_online_cpus_mems_in_subtree(const struct cpuset *cur)
+{
+ struct cpuset *c;
+
+ /* Each of our child cpusets mems must be online */
+ list_for_each_entry(c, &cur->children, sibling) {
+ guarantee_online_cpus_mems_in_subtree(c);
+ if (!cpus_empty(c->cpus_allowed))
+ guarantee_online_cpus(c, &c->cpus_allowed);
+ if (!nodes_empty(c->mems_allowed))
+ guarantee_online_mems(c, &c->mems_allowed);
+ }
+}
+
+/*
+ * The cpus_allowed and mems_allowed nodemasks in the top_cpuset track
+ * cpu_online_map and node_online_map. Force the top cpuset to track
+ * whats online after any CPU or memory node hotplug or unplug event.
+ *
+ * To ensure that we don't remove a CPU or node from the top cpuset
+ * that is currently in use by a child cpuset (which would violate
+ * the rule that cpusets must be subsets of their parent), we first
+ * call the recursive routine guarantee_online_cpus_mems_in_subtree().
+ *
+ * Since there are two callers of this routine, one for CPU hotplug
+ * events and one for memory node hotplug events, we could have coded
+ * two separate routines here. We code it as a single common routine
+ * in order to minimize text size.
+ */
+
+static void common_cpu_mem_hotplug_unplug(void)
+{
+ mutex_lock(&manage_mutex);
+ mutex_lock(&callback_mutex);
+
+ guarantee_online_cpus_mems_in_subtree(&top_cpuset);
+ top_cpuset.cpus_allowed = cpu_online_map;
+ top_cpuset.mems_allowed = node_online_map;
+
+ mutex_unlock(&callback_mutex);
+ mutex_unlock(&manage_mutex);
+}
+#endif
+
+#ifdef CONFIG_HOTPLUG_CPU
/*
* The top_cpuset tracks what CPUs and Memory Nodes are online,
* period. This is necessary in order to make cpusets transparent
@@ -2050,38 +2117,24 @@ out:
* cpu_online_map on each CPU hotplug (cpuhp) event.
*/
-#ifdef CONFIG_HOTPLUG_CPU
static int cpuset_handle_cpuhp(struct notifier_block *nb,
unsigned long phase, void *cpu)
{
- mutex_lock(&manage_mutex);
- mutex_lock(&callback_mutex);
-
- top_cpuset.cpus_allowed = cpu_online_map;
-
- mutex_unlock(&callback_mutex);
- mutex_unlock(&manage_mutex);
-
+ common_cpu_mem_hotplug_unplug();
return 0;
}
#endif
+#ifdef CONFIG_MEMORY_HOTPLUG
/*
* Keep top_cpuset.mems_allowed tracking node_online_map.
* Call this routine anytime after you change node_online_map.
* See also the previous routine cpuset_handle_cpuhp().
*/
-#ifdef CONFIG_MEMORY_HOTPLUG
void cpuset_track_online_nodes()
{
- mutex_lock(&manage_mutex);
- mutex_lock(&callback_mutex);
-
- top_cpuset.mems_allowed = node_online_map;
-
- mutex_unlock(&callback_mutex);
- mutex_unlock(&manage_mutex);
+ common_cpu_mem_hotplug_unplug();
}
#endif