Re: [PATCH] memcg: do not expose uninitialized mem_cgroup_per_nodeto world

[Andrew Morton]

The original patch:

--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4707,7 +4707,6 @@ static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
 	if (!pn)
 		return 1;
 
-	mem->info.nodeinfo[node] = pn;
 	for (zone = 0; zone < MAX_NR_ZONES; zone++) {
 		mz = &pn->zoneinfo[zone];
 		for_each_lru(l)
@@ -4716,6 +4715,7 @@ static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
 		mz->on_tree = false;
 		mz->mem = mem;
 	}
+	mem->info.nodeinfo[node] = pn;
 	return 0;
 }

looks like a really good idea.  But it needs a new changelog and I'd be
a bit reluctant to merge it as it appears that the aptch removes our
only known way of reproducing a bug.

So for now I think I'll queue the patch up unchangelogged so the issue
doesn't get forgotten about.

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