Re: [PATCH] netfilter: per netns nf_conntrack_cachep

Patrick McHardy
2010-02-04T13:37:30Z

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Jon Masters wrote:
> On Thu, 2010-02-04 at 14:04 +0100, Patrick McHardy wrote:
>> In any case, we need a fix for this suitable for 2.6.33. If
>> you don't like using the pointer, please send a patch to add
>> an id to the network namespaces.
>
> Right. I think the quick solution is fine for 2.6.33. So that makes the
> hashtable non-resize patch, the crash fix, and the cachep bits. I will
> try to get involved and help you out with the per-ns hashtable clean
> rather than just being a whiner :)

This is the patch I'm going to commit unless unless there are further
objections. Its Eric's patch with a change on top to allocate a unique
name for the slab.

> Thanks a bunch! Fedora kernels have already been built with this fix,
> since it will allow us to close a fair number of "KVM goes boom" bugs.

Thanks as well for your help.

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diff --git a/include/net/netns/conntrack.h b/include/net/netns/conntrack.h
index ba1ba0c..aed23b6 100644
--- a/include/net/netns/conntrack.h
+++ b/include/net/netns/conntrack.h
@@ -11,6 +11,7 @@ struct nf_conntrack_ecache;
struct netns_ct {
atomic_t count;
unsigned int expect_count;
+ struct kmem_cache *nf_conntrack_cachep;
struct hlist_nulls_head *hash;
struct hlist_head *expect_hash;
struct hlist_nulls_head unconfirmed;
@@ -28,5 +29,6 @@ struct netns_ct {
#endif
int hash_vmalloc;
int expect_vmalloc;
+ char *slabname;
};
#endif
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index 37e2b88..7ac027a 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -63,8 +63,6 @@ EXPORT_SYMBOL_GPL(nf_conntrack_max);
struct nf_conn nf_conntrack_untracked __read_mostly;
EXPORT_SYMBOL_GPL(nf_conntrack_untracked);

-static struct kmem_cache *nf_conntrack_cachep __read_mostly;
-
static int nf_conntrack_hash_rnd_initted;
static unsigned int nf_conntrack_hash_rnd;

@@ -572,7 +570,7 @@ struct nf_conn *nf_conntrack_alloc(struct net *net,
* Do not use kmem_cache_zalloc(), as this cache uses
* SLAB_DESTROY_BY_RCU.
*/
- ct = kmem_cache_alloc(nf_conntrack_cachep, gfp);
+ ct = kmem_cache_alloc(net->ct.nf_conntrack_cachep, gfp);
if (ct == NULL) {
pr_debug("nf_conntrack_alloc: Can't alloc conntrack.\n");
atomic_dec(&net->ct.count);
@@ -611,7 +609,7 @@ void nf_conntrack_free(struct nf_conn *ct)
nf_ct_ext_destroy(ct);
atomic_dec(&net->ct.count);
nf_ct_ext_free(ct);
- kmem_cache_free(nf_conntrack_cachep, ct);
+ kmem_cache_free(net->ct.nf_conntrack_cachep, ct);
}
EXPORT_SYMBOL_GPL(nf_conntrack_free);

@@ -1119,7 +1117,6 @@ static void nf_conntrack_cleanup_init_net(void)

nf_conntrack_helper_fini();
nf_conntrack_proto_fini();
- kmem_cache_destroy(nf_conntrack_cachep);
}

static void nf_conntrack_cleanup_net(struct net *net)
@@ -1137,6 +1134,8 @@ static void nf_conntrack_cleanup_net(struct net *net)
nf_conntrack_ecache_fini(net);
nf_conntrack_acct_fini(net);
nf_conntrack_expect_fini(net);
+ kmem_cache_destroy(net->ct.nf_conntrack_cachep);
+ kfree(net->ct.slabname);
free_percpu(net->ct.stat);
}

@@ -1272,15 +1271,6 @@ static int nf_conntrack_init_init_net(void)
NF_CONNTRACK_VERSION, nf_conntrack_htable_size,
nf_conntrack_max);

- nf_conntrack_cachep = kmem_cache_create("nf_conntrack",
- sizeof(struct nf_conn),
- 0, SLAB_DESTROY_BY_RCU, NULL);
- if (!nf_conntrack_cachep) {
- printk(KERN_ERR "Unable to create nf_conn slab cache\n");
- ret = -ENOMEM;
- goto err_cache;
- }
-
ret = nf_conntrack_proto_init();
if (ret < 0)
goto err_proto;
@@ -1302,8 +1292,6 @@ static int nf_conntrack_init_init_net(void)
err_helper:
nf_conntrack_proto_fini();
err_proto:
- kmem_cache_destroy(nf_conntrack_cachep);
-err_cache:
return ret;
}

@@ -1325,6 +1313,19 @@ static int nf_conntrack_init_net(struct net *net)
ret = -ENOMEM;
goto err_stat;
}
+
+ net->ct.slabname = kasprintf(GFP_KERNEL, "nf_conntrack_%p", net);
+ if (!net->ct.slabname)
+ goto err_slabname;
+
+ net->ct.nf_conntrack_cachep = kmem_cache_create(net->ct.slabname,
+ sizeof(struct nf_conn), 0,
+ SLAB_DESTROY_BY_RCU, NULL);
+ if (!net->ct.nf_conntrack_cachep) {
+ printk(KERN_ERR "Unable to create nf_conn slab cache\n");
+ ret = -ENOMEM;
+ goto err_cache;
+ }
net->ct.hash = nf_ct_alloc_hashtable(&nf_conntrack_htable_size,
&net->ct.hash_vmalloc, 1);
if (!net->ct.hash) {
@@ -1352,6 +1353,10 @@ err_expect:
nf_ct_free_hashtable(net->ct.hash, net->ct.hash_vmalloc,
nf_conntrack_htable_size);
err_hash:
+ kmem_cache_destroy(net->ct.nf_conntrack_cachep);
+err_cache:
+ kfree(net->ct.slabname);
+err_slabname:
free_percpu(net->ct.stat);
err_stat:
return ret;