Messages in this thread Patch in this message | | | Date | Mon, 15 Dec 2014 20:22:17 +0900 | From | Kamezawa Hiroyuki <> | Subject | [PATCH 4/4] workqueue: Handle cpu-node affinity change at CPU_ONLINE. |
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This is a corner case fix. In general, cpu-to-node relationship is fixed when cpu/memory are visible to kernel based on firmware information. But in some case, cpu-to-node relationship is updated at CPU_ONLINE.
In arch/x86/mm/numa.c::numa_init_array(), a cpu will be tied to a random numa node if the node firmware tells is memry-less node. Such cpu's cpu affinity can be changed in cpu_up().
For example, step 1. boot with mem= boot option, hide memory. step 2. online hidden memory with using memory hot-add. step 3. offline cpus. step 4. online cpus.
In step 4, cpu's numa node affinity can be modified if memory-less node turns out to be an usual node by step 2.
This patch handles the event in CPU_ONLINE callback of workqueue.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> --- kernel/workqueue.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 5499b76..cc0e1d4 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -4583,6 +4583,20 @@ void workqueue_node_register(int node) } mutex_unlock(&wq_pool_mutex); } +/* + * When a cpu boot up with a memory less node, the cpu is be tied + * a random node (see arch/x86/mm/numa.c::numa_init_array()). + * The relationship is fixed when a proper memory node comes up and + * it's visible after CPU_ONLINE. check and reflesh it. + */ +void check_reflesh_node_cpumask(int cpu) +{ + int node = cpu_to_node(cpu); + + if (likely(cpumask_test_cpu(cpu, wq_numa_possible_cpumask[node]))) + return; + reflesh_wq_possible_mask(cpu, node); +} #endif @@ -4617,6 +4631,7 @@ static int workqueue_cpu_up_callback(struct notifier_block *nfb, */ for_each_cpu_worker_pool(pool, cpu) pool->node = cpu_to_node(cpu); + check_reflesh_node_cpumask(cpu); for_each_pool(pool, pi) { mutex_lock(&pool->attach_mutex); -- 1.8.3.1
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