Re: BUG: soft lockup - CPU#8 stuck for 22s!

[Mel Gorman <mgorman@suse.de>]

On Tue, Oct 22, 2013 at 01:29:22PM -0400, Don Morris wrote:
> Greetings, all.
> 
> Just wanted to drop this out there to see if it rang any bells.
> I've been getting a soft lockup (numad thread stuck on a cpu
> while attempting to attach a task to a cgroup) for a while now,
> but I thought it was only happening when I applied Mel Gorman's
> set of AutoNUMA patches.

This maybe?

---8<---
mm: memcontrol: Release css_set_lock when aborting an OOM scan

css_task_iter_start acquires the css_set_lock and it must be released with
a call to css_task_iter_end. Commmit 9cbb78bb (mm, memcg: introduce own
oom handler to iterate only over its own threads) introduced a loop that
was not guaranteed to call css_task_iter_end.

Cc: stable <stable@vger.kernel.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5ef8929..941f67d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1795,6 +1795,7 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
 				mem_cgroup_iter_break(memcg, iter);
 				if (chosen)
 					put_task_struct(chosen);
+				css_task_iter_end(&it);
 				return;
 			case OOM_SCAN_OK:
 				break;