On Fri, Jan 23, 2015 at 08:59:51AM -0800, Guenter Roeck wrote:
> On 01/23/2015 08:02 AM, Johannes Weiner wrote:
> >On Fri, Jan 23, 2015 at 09:17:44AM -0600, Christoph Lameter wrote:
> >>On Fri, 23 Jan 2015, Johannes Weiner wrote:
> >>
> >>>Is the assumption of this patch wrong? Does the specified node have
> >>>to be online for the fallback to work?
> >>
> >>Nodes that are offline have no control structures allocated and thus
> >>allocations will likely segfault when the address of the controls
> >>structure for the node is accessed.
> >>
> >>If we wanted to prevent that then every allocation would have to add a
> >>check to see if the nodes are online which would impact performance.
> >
> >Okay, that makes sense, thank you.
> >
> >Andrew, can you please drop this patch?
> >
> Problem is that there are three patches.
>
> 2537ffb mm: memcontrol: consolidate swap controller code
> 2f9b346 mm: memcontrol: consolidate memory controller initialization
> a40d0d2 mm: memcontrol: remove unnecessary soft limit tree node test
>
> Reverting (or dropping) a40d0d2 alone is not possible since it modifies
> mem_cgroup_soft_limit_tree_init which is removed by 2f9b346.
("mm: memcontrol: consolidate swap controller code") gave me no issues
when rebasing, but ("mm: memcontrol: consolidate memory controller
initialization") needs updating.
So how about this one to replace ("mm: memcontrol: remove unnecessary
soft limit tree node test"):
---
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: [patch] mm: memcontrol: simplify soft limit tree init code
- No need to test the node for N_MEMORY. node_online() is enough for
node fallback to work in slab, use NUMA_NO_NODE for everything else.
- Remove the BUG_ON() for allocation failure. A NULL pointer crash is
just as descriptive, and the absent return value check is obvious.
- Move local variables to the inner-most blocks.
- Point to the tree structure after its initialized, not before, it's
just more logical that way.
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
mm/memcontrol.c | 17 ++++++++---------
1 file changed, 8 insertions(+), 9 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index fb9788af4a3e..88c67303d141 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4537,24 +4537,23 @@ EXPORT_SYMBOL(parent_mem_cgroup);
static void __init mem_cgroup_soft_limit_tree_init(void)
{
- struct mem_cgroup_tree_per_node *rtpn;
- struct mem_cgroup_tree_per_zone *rtpz;
- int tmp, node, zone;
+ int node;
for_each_node(node) {
- tmp = node;
- if (!node_state(node, N_NORMAL_MEMORY))
- tmp = -1;
- rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL, tmp);
- BUG_ON(!rtpn);
+ struct mem_cgroup_tree_per_node *rtpn;
+ int zone;
- soft_limit_tree.rb_tree_per_node[node] = rtpn;
+ rtpn = kzalloc_node(sizeof(*rtpn), GFP_KERNEL,
+ node_online(node) ? node : NUMA_NO_NODE);
for (zone = 0; zone < MAX_NR_ZONES; zone++) {
+ struct mem_cgroup_tree_per_zone *rtpz;
+
rtpz = &rtpn->rb_tree_per_zone[zone];
rtpz->rb_root = RB_ROOT;
spin_lock_init(&rtpz->lock);
}
+ soft_limit_tree.rb_tree_per_node[node] = rtpn;
}
}
--
2.2.2
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