(2014/12/17 10:36), Lai Jiangshan wrote:
On 12/17/2014 12:45 AM, Kamezawa Hiroyuki wrote:
With node online/offline, cpu<->node relationship is established.
Workqueue uses a info which was established at boot time but
it may be changed by node hotpluging.
Once pool->node points to a stale node, following allocation failure
happens.
==
SLUB: Unable to allocate memory on node 2 (gfp=0x80d0)
cache: kmalloc-192, object size: 192, buffer size: 192, default
order:
1, min order: 0
node 0: slabs: 6172, objs: 259224, free: 245741
node 1: slabs: 3261, objs: 136962, free: 127656
==
This patch updates per cpu workqueue pool's node affinity and
updates wq_numa_possible_cpumask at node online/offline event.
This update of mask is very important because it affects cpumasks
and preferred node detection.
Unbound workqueue's per node pool are updated by
by wq_update_unbound_numa() at CPU_DOWN_PREPARE of the last cpu, by existing
code.
What important here is to avoid wrong node detection when a cpu get onlined.
And it's handled by wq_numa_possible_cpumask update introduced by this patch.
Changelog v3->v4:
- added workqueue_node_unregister
- clear wq_numa_possible_cpumask at node offline.
- merged a patch which handles per cpu pools.
- clear per-cpu-pool's pool->node at node offlining.
- set per-cpu-pool's pool->node at node onlining.
- dropped modification to get_unbound_pool()
- dropped per-cpu-pool handling at cpu online/offline.
Reported-by: Yasuaki Ishimatsu <isimatu.yasu...@jp.fujitsu.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hir...@jp.fujitsu.com>
---
include/linux/memory_hotplug.h | 3 +++
kernel/workqueue.c | 58 +++++++++++++++++++++++++++++++++++++++++-
mm/memory_hotplug.c | 6 ++++-
3 files changed, 65 insertions(+), 2 deletions(-)
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 8f1a419..7b4a292 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -270,4 +270,7 @@ extern void sparse_remove_one_section(struct zone *zone,
struct mem_section *ms)
extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
unsigned long pnum);
+/* update for workqueues */
+void workqueue_node_register(int node);
+void workqueue_node_unregister(int node);
#endif /* __LINUX_MEMORY_HOTPLUG_H */
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 6202b08..f6ad05a 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -266,7 +266,7 @@ struct workqueue_struct {
static struct kmem_cache *pwq_cache;
static cpumask_var_t *wq_numa_possible_cpumask;
- /* possible CPUs of each node */
+ /* PL: possible CPUs of each node */
static bool wq_disable_numa;
module_param_named(disable_numa, wq_disable_numa, bool, 0444);
@@ -4563,6 +4563,62 @@ static void restore_unbound_workers_cpumask(struct
worker_pool *pool, int cpu)
WARN_ON_ONCE(set_cpus_allowed_ptr(worker->task,
pool->attrs->cpumask) < 0);
}
+#ifdef CONFIG_MEMORY_HOTPLUG
+
+static void workqueue_update_cpu_numa_affinity(int cpu, int node)
+{
+ struct worker_pool *pool;
+
+ if (node != cpu_to_node(cpu))
+ return;
+ cpumask_set_cpu(cpu, wq_numa_possible_cpumask[node]);
+ for_each_cpu_worker_pool(pool, cpu)
+ pool->node = node;
Again, You need to check and update all the wq->numa_pwq_tbl[oldnode],
but in this patchset, the required information is lost and we can't find out
oldnode.
cpus of oldnode, 16-31(online),48,56,64,72(offline,randomly assigned to the
oldnode by numa_init_array())
and then cpu#48 is allocated for newnode and online
Now, the wq->numa_pwq_tbl[oldnode]'s cpumask still have cpu#48, and it may be
scheduled to cpu#48.
See the information of my patch 4/5
That will not cause page allocation failure, right ? If so, it's out of scope
of this patch 1/2.
I think it's handled in patch 2/2, isn't it ?
Thanks,
-Kame
+}
+
+/*
+ * When a cpu is physically added, cpu<->node relationship is established
+ * based on firmware info. We can catch the whole view when a new NODE_DATA()
+ * coming up (a node is added).
+ * If we don't update the info, pool->node will points to a not-online node
+ * and the kernel will have allocation failure.
+ *
+ * Update wp_numa_possible_mask at online and clear it at offline.
+ */
+void workqueue_node_register(int node)
+{
+ int cpu;
+
+ mutex_lock(&wq_pool_mutex);
+ for_each_possible_cpu(cpu)
+ workqueue_update_cpu_numa_affinity(cpu, node);
+ /* unbound workqueue will be updated when the 1st cpu comes up.*/
+ mutex_unlock(&wq_pool_mutex);
+}
+
+void workqueue_node_unregister(int node)
+{
+ struct worker_pool *pool;
+ int cpu;
+
+ mutex_lock(&wq_pool_mutex);
+ cpumask_clear(wq_numa_possible_cpumask[node]);
+ for_each_possible_cpu(cpu) {
+ if (node == cpu_to_node(cpu))
+ for_each_cpu_worker_pool(pool, cpu)
+ pool->node = NUMA_NO_NODE;
+ }
+ /*
+ * unbound workqueue's per-node pwqs are already refleshed
+ * by wq_update_unbound_numa() at CPU_DOWN_PREPARE of the last cpu
+ * on this node, because all cpus of this node went down.
+ * (see wq_calc_node_cpumask()). per-node unbound pwqs has been replaced
+ * with wq->dfl_pwq, already.
+ */
+ mutex_unlock(&wq_pool_mutex);
+}
+
+#endif
/*
* Workqueues should be brought up before normal priority CPU notifiers.
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9fab107..a0cb5c1 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1122,6 +1122,9 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64
start)
*/
reset_node_present_pages(pgdat);
+ /* Update workqueue's numa affinity info. */
+ workqueue_node_register(nid);
+
return pgdat;
}
@@ -1958,7 +1961,8 @@ void try_offline_node(int nid)
if (check_and_unmap_cpu_on_node(pgdat))
return;
-
+ /* update workqueue's numa affinity info. */
+ workqueue_node_unregister(nid);
/*
* all memory/cpu of this node are removed, we can offline this
* node now.
--
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