diff options
| -rw-r--r-- | kernel/cpuset.c | 87 |
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 |