Re: [RFC] kthread_create_on_node is failing to honor the node choice

[Nathan Zimmer]

On Thu, Jul 09, 2015 at 03:12:59PM -0700, Andrew Morton wrote:
> On Thu, 25 Jun 2015 16:44:13 -0500 Nathan Zimmer <nzimmer@xxxxxxx> wrote:
> 
> > In kthread_create_on_node we set_cpus_allowed to cpu_all_mask
> > regardless of what the node is requested.
> > This seems incorrect.
> 
> The `node' arg to kthread_create_on_node() refers to which node the
> task_struct and thread_info are allocated from.  It doesn't refer to
> the CPUs upon which the thread is executed.  See
> kthread_create_info.node and that gruesome task_struct.pref_node_fork
> thing.
> 
> The kthread_create_on_node() kerneldoc explains this, in a confused
> way.  It needs a s/-1/NUMA_NO_NODE/.


I suspect we should also update the kthread_create macro to use NUMA_NO_NODE also.


diff --git a/include/linux/kthread.h b/include/linux/kthread.h
index 13d5520..3e6773e 100644
--- a/include/linux/kthread.h
+++ b/include/linux/kthread.h
@@ -11,7 +11,7 @@ struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
 					   const char namefmt[], ...);
 
 #define kthread_create(threadfn, data, namefmt, arg...) \
-	kthread_create_on_node(threadfn, data, -1, namefmt, ##arg)
+	kthread_create_on_node(threadfn, data, NUMA_NO_NODE, namefmt, ##arg)
 
 
 struct task_struct *kthread_create_on_cpu(int (*threadfn)(void *data),
--
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