From 2510c5664eabb0a53cfccb571ed137e47d87f9df Mon Sep 17 00:00:00 2001
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Date: Thu, 1 Dec 2011 14:28:04 -0700
Subject: [PATCH 1/2] UBUNTU: SAUCE: netns: Add quota for number of NET_NS instances.
CONFIG_NET_NS support in 2.6.32 has a problem that leads to OOM killer when
clone(CLONE_NEWNET) is called instantly.
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/720095
But disabling CONFIG_NET_NS broke lxc containers.
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/790863
This patch introduces /proc/sys/net/core/netns_max interface that limits
max number of network namespace instances.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>
---
include/net/sock.h | 4 ++++
net/core/net_namespace.c | 13 +++++++++++++
net/core/sysctl_net_core.c | 10 ++++++++++
3 files changed, 27 insertions(+), 0 deletions(-)
@@ -1620,4 +1620,8 @@ extern int sysctl_optmem_max;
extern __u32 sysctl_wmem_default;
extern __u32 sysctl_rmem_default;
+#ifdef CONFIG_NET_NS
+extern int max_netns_count;
+#endif
+
#endif /* _SOCK_H */
@@ -81,12 +81,22 @@ static struct net_generic *net_alloc_generic(void)
#ifdef CONFIG_NET_NS
static struct kmem_cache *net_cachep;
static struct workqueue_struct *netns_wq;
+static atomic_t used_netns_count = ATOMIC_INIT(0);
+unsigned int max_netns_count = 1024;
static struct net *net_alloc(void)
{
struct net *net = NULL;
struct net_generic *ng;
+ atomic_inc(&used_netns_count);
+ if (atomic_read(&used_netns_count) >= max_netns_count) {
+ printk_once(KERN_WARNING
+ "net_alloc: Exceeded maximum (%d) net namespace allocations.\n",
+ max_netns_count);
+ goto out;
+ }
+
ng = net_alloc_generic();
if (!ng)
goto out;
@@ -96,7 +106,9 @@ static struct net *net_alloc(void)
goto out_free;
rcu_assign_pointer(net->gen, ng);
+ return net;
out:
+ atomic_dec(&used_netns_count);
return net;
out_free:
@@ -115,6 +127,7 @@ static void net_free(struct net *net)
#endif
kfree(net->gen);
kmem_cache_free(net_cachep, net);
+ atomic_dec(&used_netns_count);
}
static struct net *net_create(void)
@@ -89,6 +89,16 @@ static struct ctl_table net_core_table[] = {
.mode = 0644,
.proc_handler = proc_dointvec
},
+#ifdef CONFIG_NET_NS
+ {
+ .ctl_name = CTL_UNNUMBERED,
+ .procname = "netns_max",
+ .data = &max_netns_count,
+ .maxlen = sizeof(int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
+#endif
#endif /* CONFIG_NET */
{
.ctl_name = NET_CORE_BUDGET,
--
1.7.0.4