Badari, I think you used SLUB. If so, page_cgroup's notifier callback was not

called and newly allocated page's page_cgroup wasn't allocated.

This is a fix. (notifier saw STOP_HERE flag added by slub's notifier.)
I'm now testing modified kernel, which does alloc/free page_cgroup by notifier.

(Usually, all page_cgroups are from bootmem and not freed.

 so, modified a bit for test)
And I cannot reproduce panic. I think you do "real" memory hotplug other than

online/offline and saw panic caused by this. 
Is this slub's behavior intentional ? page_cgroup's notifier has lower priority

than slub, now.
Thanks,

-Kame

==

notifier callback's notifier_from_errno() just works well in error

route. (It adds mask for "stop here")
Hanlder should return NOTIFY_OK in explict way.
Signed-off-by:KAMEZAWA Hiroyuki

---

 mm/page_cgroup.c |    5 ++++-

 mm/slub.c        |    6 ++++--

 2 files changed, 8 insertions(+), 3 deletions(-)
Index: mmotm-2.6.28-Nov10/mm/slub.c

===================================================================

--- mmotm-2.6.28-Nov10.orig/mm/slub.c

+++ mmotm-2.6.28-Nov10/mm/slub.c

@@ -3220,8 +3220,10 @@ static int slab_memory_callback(struct n

 	case MEM_CANCEL_OFFLINE:

 		break;

 	}

-

-	ret = notifier_from_errno(ret);

+	if (ret)

+		ret = notifier_from_errno(ret);

+	else

+		ret = NOTIFY_OK;

 	return ret;

 }
Index: mmotm-2.6.28-Nov10/mm/page_cgroup.c

===================================================================

--- mmotm-2.6.28-Nov10.orig/mm/page_cgroup.c

+++ mmotm-2.6.28-Nov10/mm/page_cgroup.c

@@ -216,7 +216,10 @@ static int page_cgroup_callback(struct n

 		break;

 	}
-	ret = notifier_from_errno(ret);

+	if (ret)

+		ret = notifier_from_errno(ret);

+	else

+		ret = NOTIFY_OK;
 	return ret;

 }
--

unsubscribe notice
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in

the body of a message to majordomo@vger.kernel.org

More majordomo info at  http://vger.kernel.org/majordomo-info.html

Please read the FAQ at  http://www.tux.org/lkml/