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 > +} > + > +/* > + * 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/