Re: [memcg BUG] NULL pointer dereference wheng rmdir

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Mon, 19 Jan 2009 17:15:05 +0800
Li Zefan <lizf@cn.fujitsu.com> wrote:

> note: rmdir[11520] exited with preempt_count 1
> ===========================================================================
> 
> 
> And I've confirmed it's because (zone == NULL) in mem_cgroup_force_empty_list():
> 
> 
Hmm, curious.  it will be

==
	for_each_node_state(nid, N_POSSIBLE)
		for (zid = 0; zid < MAX_NR_ZONES; zid++)
			zone = &NODE_DATA(nid)->node_zones[zid];

==

And, from this message,

Unable to handle kernel NULL pointer dereference (address 0000000000002680)

NODE_DATA(nid) seems to be NULL.

Hmm...could you try this ? Thank you for nice test, very helpful.
-Kame
==
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

N_POSSIBLE doesn't means there is memory...and force_empty can
visit invalud node which have no pgdat.

To visit all valid nodes, N_HIGH_MEMRY should be used.

Reporetd-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>

---
 mm/memcontrol.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: mmotm-2.6.29-Jan16/mm/memcontrol.c
===================================================================
--- mmotm-2.6.29-Jan16.orig/mm/memcontrol.c
+++ mmotm-2.6.29-Jan16/mm/memcontrol.c
@@ -1724,7 +1724,7 @@ move_account:
 		/* This is for making all *used* pages to be on LRU. */
 		lru_add_drain_all();
 		ret = 0;
-		for_each_node_state(node, N_POSSIBLE) {
+		for_each_node_state(node, N_HIGH_MEMORY) {
 			for (zid = 0; !ret && zid < MAX_NR_ZONES; zid++) {
 				enum lru_list l;
 				for_each_lru(l) {

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>