[PATCH] openvswitch: make for_each_node loops work with sparse numa systems

[PATCH] openvswitch: make for_each_node loops work with sparse numa systems

[Chris J Arges]

Some architectures like POWER can have a NUMA node_possible_map that
contains sparse entries. This causes memory corruption with openvswitch
since it allocates flow_cache with a multiple of num_possible_nodes() and
assumes the node variable returned by for_each_node will index into
flow->stats[node].

For example, if node_possible_map is 0x30003, this patch will map node to
node_cnt as follows:
    0,1,16,17 => 0,1,2,3

The crash was noticed after 3af229f2 was applied as it changed the
node_possible_map to match node_online_map on boot.
Fixes: 3af229f2071f5b5cb31664be6109561fbe19c861

Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
---
 net/openvswitch/flow.c       | 10 ++++++----
 net/openvswitch/flow_table.c | 18 +++++++++++-------
 2 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index bc7b0ab..425d45d 100644
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -134,14 +134,14 @@ void ovs_flow_stats_get(const struct sw_flow *flow,
 			struct ovs_flow_stats *ovs_stats,
 			unsigned long *used, __be16 *tcp_flags)
 {
-	int node;
+	int node, node_cnt = 0;
 
 	*used = 0;
 	*tcp_flags = 0;
 	memset(ovs_stats, 0, sizeof(*ovs_stats));
 
 	for_each_node(node) {
-		struct flow_stats *stats = rcu_dereference_ovsl(flow->stats[node]);
+		struct flow_stats *stats = rcu_dereference_ovsl(flow->stats[node_cnt]);
 
 		if (stats) {
 			/* Local CPU may write on non-local stats, so we must
@@ -155,16 +155,17 @@ void ovs_flow_stats_get(const struct sw_flow *flow,
 			ovs_stats->n_bytes += stats->byte_count;
 			spin_unlock_bh(&stats->lock);
 		}
+		node_cnt++;
 	}
 }
 
 /* Called with ovs_mutex. */
 void ovs_flow_stats_clear(struct sw_flow *flow)
 {
-	int node;
+	int node, node_cnt = 0;
 
 	for_each_node(node) {
-		struct flow_stats *stats = ovsl_dereference(flow->stats[node]);
+		struct flow_stats *stats = ovsl_dereference(flow->stats[node_cnt]);
 
 		if (stats) {
 			spin_lock_bh(&stats->lock);
@@ -174,6 +175,7 @@ void ovs_flow_stats_clear(struct sw_flow *flow)
 			stats->tcp_flags = 0;
 			spin_unlock_bh(&stats->lock);
 		}
+		node_cnt++;
 	}
 }
 
diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
index 4613df8..5d10c54 100644
--- a/net/openvswitch/flow_table.c
+++ b/net/openvswitch/flow_table.c
@@ -77,7 +77,7 @@ struct sw_flow *ovs_flow_alloc(void)
 {
 	struct sw_flow *flow;
 	struct flow_stats *stats;
-	int node;
+	int node, node_cnt = 0;
 
 	flow = kmem_cache_alloc(flow_cache, GFP_KERNEL);
 	if (!flow)
@@ -99,9 +99,11 @@ struct sw_flow *ovs_flow_alloc(void)
 
 	RCU_INIT_POINTER(flow->stats[0], stats);
 
-	for_each_node(node)
+	for_each_node(node) {
 		if (node != 0)
-			RCU_INIT_POINTER(flow->stats[node], NULL);
+			RCU_INIT_POINTER(flow->stats[node_cnt], NULL);
+		node_cnt++;
+	}
 
 	return flow;
 err:
@@ -139,15 +141,17 @@ static struct flex_array *alloc_buckets(unsigned int n_buckets)
 
 static void flow_free(struct sw_flow *flow)
 {
-	int node;
+	int node, node_cnt = 0;
 
 	if (ovs_identifier_is_key(&flow->id))
 		kfree(flow->id.unmasked_key);
 	kfree((struct sw_flow_actions __force *)flow->sf_acts);
-	for_each_node(node)
-		if (flow->stats[node])
+	for_each_node(node) {
+		if (flow->stats[node_cnt])
 			kmem_cache_free(flow_stats_cache,
-					(struct flow_stats __force *)flow->stats[node]);
+					(struct flow_stats __force *)flow->stats[node_cnt]);
+		node_cnt++;
+	}
 	kmem_cache_free(flow_cache, flow);
 }
 
-- 
1.9.1

Re: [PATCH] openvswitch: make for_each_node loops work with sparse numa systems

[Nishanth Aravamudan]

On 21.07.2015 [10:32:34 -0500], Chris J Arges wrote:
> Some architectures like POWER can have a NUMA node_possible_map that
> contains sparse entries. This causes memory corruption with openvswitch
> since it allocates flow_cache with a multiple of num_possible_nodes() and

Couldn't this also be fixed by just allocationg with a multiple of
nr_node_ids (which seems to have been the original intent all along)?
You could then make your stats array be sparse or not.

> assumes the node variable returned by for_each_node will index into
> flow->stats[node].
> 
> For example, if node_possible_map is 0x30003, this patch will map node to
> node_cnt as follows:
>     0,1,16,17 => 0,1,2,3
> 
> The crash was noticed after 3af229f2 was applied as it changed the
> node_possible_map to match node_online_map on boot.
> Fixes: 3af229f2071f5b5cb31664be6109561fbe19c861

My concern with this version of the fix is that you're relying on,
implicitly, the order of for_each_node's iteration corresponding to the
entries in stats 1:1. But what about node hotplug? It seems better to
have the enumeration of the stats array match the topology accurately,
rather, or to maintain some sort of internal map in the OVS code between
the NUMA node and the entry in the stats array?

I'm willing to be convinced otherwise, though :)

-Nish

> Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
> ---
>  net/openvswitch/flow.c       | 10 ++++++----
>  net/openvswitch/flow_table.c | 18 +++++++++++-------
>  2 files changed, 17 insertions(+), 11 deletions(-)
> 
> diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
> index bc7b0ab..425d45d 100644
> --- a/net/openvswitch/flow.c
> +++ b/net/openvswitch/flow.c
> @@ -134,14 +134,14 @@ void ovs_flow_stats_get(const struct sw_flow *flow,
>  			struct ovs_flow_stats *ovs_stats,
>  			unsigned long *used, __be16 *tcp_flags)
>  {
> -	int node;
> +	int node, node_cnt = 0;
> 
>  	*used = 0;
>  	*tcp_flags = 0;
>  	memset(ovs_stats, 0, sizeof(*ovs_stats));
> 
>  	for_each_node(node) {
> -		struct flow_stats *stats = rcu_dereference_ovsl(flow->stats[node]);
> +		struct flow_stats *stats = rcu_dereference_ovsl(flow->stats[node_cnt]);
> 
>  		if (stats) {
>  			/* Local CPU may write on non-local stats, so we must
> @@ -155,16 +155,17 @@ void ovs_flow_stats_get(const struct sw_flow *flow,
>  			ovs_stats->n_bytes += stats->byte_count;
>  			spin_unlock_bh(&stats->lock);
>  		}
> +		node_cnt++;
>  	}
>  }
> 
>  /* Called with ovs_mutex. */
>  void ovs_flow_stats_clear(struct sw_flow *flow)
>  {
> -	int node;
> +	int node, node_cnt = 0;
> 
>  	for_each_node(node) {
> -		struct flow_stats *stats = ovsl_dereference(flow->stats[node]);
> +		struct flow_stats *stats = ovsl_dereference(flow->stats[node_cnt]);
> 
>  		if (stats) {
>  			spin_lock_bh(&stats->lock);
> @@ -174,6 +175,7 @@ void ovs_flow_stats_clear(struct sw_flow *flow)
>  			stats->tcp_flags = 0;
>  			spin_unlock_bh(&stats->lock);
>  		}
> +		node_cnt++;
>  	}
>  }
> 
> diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
> index 4613df8..5d10c54 100644
> --- a/net/openvswitch/flow_table.c
> +++ b/net/openvswitch/flow_table.c
> @@ -77,7 +77,7 @@ struct sw_flow *ovs_flow_alloc(void)
>  {
>  	struct sw_flow *flow;
>  	struct flow_stats *stats;
> -	int node;
> +	int node, node_cnt = 0;
> 
>  	flow = kmem_cache_alloc(flow_cache, GFP_KERNEL);
>  	if (!flow)
> @@ -99,9 +99,11 @@ struct sw_flow *ovs_flow_alloc(void)
> 
>  	RCU_INIT_POINTER(flow->stats[0], stats);
> 
> -	for_each_node(node)
> +	for_each_node(node) {
>  		if (node != 0)
> -			RCU_INIT_POINTER(flow->stats[node], NULL);
> +			RCU_INIT_POINTER(flow->stats[node_cnt], NULL);
> +		node_cnt++;
> +	}
> 
>  	return flow;
>  err:
> @@ -139,15 +141,17 @@ static struct flex_array *alloc_buckets(unsigned int n_buckets)
> 
>  static void flow_free(struct sw_flow *flow)
>  {
> -	int node;
> +	int node, node_cnt = 0;
> 
>  	if (ovs_identifier_is_key(&flow->id))
>  		kfree(flow->id.unmasked_key);
>  	kfree((struct sw_flow_actions __force *)flow->sf_acts);
> -	for_each_node(node)
> -		if (flow->stats[node])
> +	for_each_node(node) {
> +		if (flow->stats[node_cnt])
>  			kmem_cache_free(flow_stats_cache,
> -					(struct flow_stats __force *)flow->stats[node]);
> +					(struct flow_stats __force *)flow->stats[node_cnt]);
> +		node_cnt++;
> +	}
>  	kmem_cache_free(flow_cache, flow);
>  }
> 
> -- 
> 1.9.1
> 

Re: [PATCH] openvswitch: make for_each_node loops work with sparse numa systems

[Chris J Arges]

On Tue, Jul 21, 2015 at 09:24:18AM -0700, Nishanth Aravamudan wrote:
> On 21.07.2015 [10:32:34 -0500], Chris J Arges wrote:
> > Some architectures like POWER can have a NUMA node_possible_map that
> > contains sparse entries. This causes memory corruption with openvswitch
> > since it allocates flow_cache with a multiple of num_possible_nodes() and
> 
> Couldn't this also be fixed by just allocationg with a multiple of
> nr_node_ids (which seems to have been the original intent all along)?
> You could then make your stats array be sparse or not.
> 

Yea originally this is what I did, but I thought it would be wasting memory.

> > assumes the node variable returned by for_each_node will index into
> > flow->stats[node].
> > 
> > For example, if node_possible_map is 0x30003, this patch will map node to
> > node_cnt as follows:
> >     0,1,16,17 => 0,1,2,3
> > 
> > The crash was noticed after 3af229f2 was applied as it changed the
> > node_possible_map to match node_online_map on boot.
> > Fixes: 3af229f2071f5b5cb31664be6109561fbe19c861
> 
> My concern with this version of the fix is that you're relying on,
> implicitly, the order of for_each_node's iteration corresponding to the
> entries in stats 1:1. But what about node hotplug? It seems better to
> have the enumeration of the stats array match the topology accurately,
> rather, or to maintain some sort of internal map in the OVS code between
> the NUMA node and the entry in the stats array?
> 
> I'm willing to be convinced otherwise, though :)
> 
> -Nish
>

Nish,

The method I described should work for hotplug since it's using possible map
which AFAIK is static rather than the online map. 

Regardless, the more simple solution to solve this issue would be to just
allocate nr_node_ids number of entries and use up extra memory.

I'll send a v2 after testing it.

--chris

> > Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
> > ---
> >  net/openvswitch/flow.c       | 10 ++++++----
> >  net/openvswitch/flow_table.c | 18 +++++++++++-------
> >  2 files changed, 17 insertions(+), 11 deletions(-)
> > 
> > diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
> > index bc7b0ab..425d45d 100644
> > --- a/net/openvswitch/flow.c
> > +++ b/net/openvswitch/flow.c
> > @@ -134,14 +134,14 @@ void ovs_flow_stats_get(const struct sw_flow *flow,
> >  			struct ovs_flow_stats *ovs_stats,
> >  			unsigned long *used, __be16 *tcp_flags)
> >  {
> > -	int node;
> > +	int node, node_cnt = 0;
> > 
> >  	*used = 0;
> >  	*tcp_flags = 0;
> >  	memset(ovs_stats, 0, sizeof(*ovs_stats));
> > 
> >  	for_each_node(node) {
> > -		struct flow_stats *stats = rcu_dereference_ovsl(flow->stats[node]);
> > +		struct flow_stats *stats = rcu_dereference_ovsl(flow->stats[node_cnt]);
> > 
> >  		if (stats) {
> >  			/* Local CPU may write on non-local stats, so we must
> > @@ -155,16 +155,17 @@ void ovs_flow_stats_get(const struct sw_flow *flow,
> >  			ovs_stats->n_bytes += stats->byte_count;
> >  			spin_unlock_bh(&stats->lock);
> >  		}
> > +		node_cnt++;
> >  	}
> >  }
> > 
> >  /* Called with ovs_mutex. */
> >  void ovs_flow_stats_clear(struct sw_flow *flow)
> >  {
> > -	int node;
> > +	int node, node_cnt = 0;
> > 
> >  	for_each_node(node) {
> > -		struct flow_stats *stats = ovsl_dereference(flow->stats[node]);
> > +		struct flow_stats *stats = ovsl_dereference(flow->stats[node_cnt]);
> > 
> >  		if (stats) {
> >  			spin_lock_bh(&stats->lock);
> > @@ -174,6 +175,7 @@ void ovs_flow_stats_clear(struct sw_flow *flow)
> >  			stats->tcp_flags = 0;
> >  			spin_unlock_bh(&stats->lock);
> >  		}
> > +		node_cnt++;
> >  	}
> >  }
> > 
> > diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
> > index 4613df8..5d10c54 100644
> > --- a/net/openvswitch/flow_table.c
> > +++ b/net/openvswitch/flow_table.c
> > @@ -77,7 +77,7 @@ struct sw_flow *ovs_flow_alloc(void)
> >  {
> >  	struct sw_flow *flow;
> >  	struct flow_stats *stats;
> > -	int node;
> > +	int node, node_cnt = 0;
> > 
> >  	flow = kmem_cache_alloc(flow_cache, GFP_KERNEL);
> >  	if (!flow)
> > @@ -99,9 +99,11 @@ struct sw_flow *ovs_flow_alloc(void)
> > 
> >  	RCU_INIT_POINTER(flow->stats[0], stats);
> > 
> > -	for_each_node(node)
> > +	for_each_node(node) {
> >  		if (node != 0)
> > -			RCU_INIT_POINTER(flow->stats[node], NULL);
> > +			RCU_INIT_POINTER(flow->stats[node_cnt], NULL);
> > +		node_cnt++;
> > +	}
> > 
> >  	return flow;
> >  err:
> > @@ -139,15 +141,17 @@ static struct flex_array *alloc_buckets(unsigned int n_buckets)
> > 
> >  static void flow_free(struct sw_flow *flow)
> >  {
> > -	int node;
> > +	int node, node_cnt = 0;
> > 
> >  	if (ovs_identifier_is_key(&flow->id))
> >  		kfree(flow->id.unmasked_key);
> >  	kfree((struct sw_flow_actions __force *)flow->sf_acts);
> > -	for_each_node(node)
> > -		if (flow->stats[node])
> > +	for_each_node(node) {
> > +		if (flow->stats[node_cnt])
> >  			kmem_cache_free(flow_stats_cache,
> > -					(struct flow_stats __force *)flow->stats[node]);
> > +					(struct flow_stats __force *)flow->stats[node_cnt]);
> > +		node_cnt++;
> > +	}
> >  	kmem_cache_free(flow_cache, flow);
> >  }
> > 
> > -- 
> > 1.9.1
> > 
> 

[PATCH v2] openvswitch: allocate nr_node_ids flow_stats instead of num_possible_nodes

[Chris J Arges]

Some architectures like POWER can have a NUMA node_possible_map that
contains sparse entries. This causes memory corruption with openvswitch
since it allocates flow_cache with a multiple of num_possible_nodes() and
assumes the node variable returned by for_each_node will index into
flow->stats[node].

Use nr_node_ids to allocate a maximal sparse array instead of
num_possible_nodes().

The crash was noticed after 3af229f2 was applied as it changed the
node_possible_map to match node_online_map on boot.
Fixes: 3af229f2071f5b5cb31664be6109561fbe19c861

Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
---
 net/openvswitch/flow_table.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
index 4613df8..6552394 100644
--- a/net/openvswitch/flow_table.c
+++ b/net/openvswitch/flow_table.c
@@ -752,7 +752,7 @@ int ovs_flow_init(void)
 	BUILD_BUG_ON(sizeof(struct sw_flow_key) % sizeof(long));
 
 	flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow)
-				       + (num_possible_nodes()
+				       + (nr_node_ids
 					  * sizeof(struct flow_stats *)),
 				       0, 0, NULL);
 	if (flow_cache == NULL)
-- 
1.9.1

Re: [PATCH v2] openvswitch: allocate nr_node_ids flow_stats instead of num_possible_nodes

[Pravin Shelar]

On Tue, Jul 21, 2015 at 10:36 AM, Chris J Arges
<chris.j.arges@canonical.com> wrote:
> Some architectures like POWER can have a NUMA node_possible_map that
> contains sparse entries. This causes memory corruption with openvswitch
> since it allocates flow_cache with a multiple of num_possible_nodes() and
> assumes the node variable returned by for_each_node will index into
> flow->stats[node].
>
> Use nr_node_ids to allocate a maximal sparse array instead of
> num_possible_nodes().
>
> The crash was noticed after 3af229f2 was applied as it changed the
> node_possible_map to match node_online_map on boot.
> Fixes: 3af229f2071f5b5cb31664be6109561fbe19c861
>
> Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>

Acked-by: Pravin B Shelar <pshelar@nicira.com>

Thanks.

Re: [PATCH v2] openvswitch: allocate nr_node_ids flow_stats instead of num_possible_nodes

[Nishanth Aravamudan]

On 21.07.2015 [12:36:33 -0500], Chris J Arges wrote:
> Some architectures like POWER can have a NUMA node_possible_map that
> contains sparse entries. This causes memory corruption with openvswitch
> since it allocates flow_cache with a multiple of num_possible_nodes() and
> assumes the node variable returned by for_each_node will index into
> flow->stats[node].
> 
> Use nr_node_ids to allocate a maximal sparse array instead of
> num_possible_nodes().
> 
> The crash was noticed after 3af229f2 was applied as it changed the
> node_possible_map to match node_online_map on boot.
> Fixes: 3af229f2071f5b5cb31664be6109561fbe19c861
> 
> Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>
Acked-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
> ---
>  net/openvswitch/flow_table.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/net/openvswitch/flow_table.c b/net/openvswitch/flow_table.c
> index 4613df8..6552394 100644
> --- a/net/openvswitch/flow_table.c
> +++ b/net/openvswitch/flow_table.c
> @@ -752,7 +752,7 @@ int ovs_flow_init(void)
>  	BUILD_BUG_ON(sizeof(struct sw_flow_key) % sizeof(long));
> 
>  	flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow)
> -				       + (num_possible_nodes()
> +				       + (nr_node_ids
>  					  * sizeof(struct flow_stats *)),
>  				       0, 0, NULL);
>  	if (flow_cache == NULL)
> -- 
> 1.9.1
> 

Re: [PATCH] openvswitch: make for_each_node loops work with sparse numa systems

[Nishanth Aravamudan]

On 21.07.2015 [11:30:58 -0500], Chris J Arges wrote:
> On Tue, Jul 21, 2015 at 09:24:18AM -0700, Nishanth Aravamudan wrote:
> > On 21.07.2015 [10:32:34 -0500], Chris J Arges wrote:
> > > Some architectures like POWER can have a NUMA node_possible_map that
> > > contains sparse entries. This causes memory corruption with openvswitch
> > > since it allocates flow_cache with a multiple of num_possible_nodes() and
> > 
> > Couldn't this also be fixed by just allocationg with a multiple of
> > nr_node_ids (which seems to have been the original intent all along)?
> > You could then make your stats array be sparse or not.
> > 
> 
> Yea originally this is what I did, but I thought it would be wasting memory.
> 
> > > assumes the node variable returned by for_each_node will index into
> > > flow->stats[node].
> > > 
> > > For example, if node_possible_map is 0x30003, this patch will map node to
> > > node_cnt as follows:
> > >     0,1,16,17 => 0,1,2,3
> > > 
> > > The crash was noticed after 3af229f2 was applied as it changed the
> > > node_possible_map to match node_online_map on boot.
> > > Fixes: 3af229f2071f5b5cb31664be6109561fbe19c861
> > 
> > My concern with this version of the fix is that you're relying on,
> > implicitly, the order of for_each_node's iteration corresponding to the
> > entries in stats 1:1. But what about node hotplug? It seems better to
> > have the enumeration of the stats array match the topology accurately,
> > rather, or to maintain some sort of internal map in the OVS code between
> > the NUMA node and the entry in the stats array?
> > 
> > I'm willing to be convinced otherwise, though :)
> > 
> > -Nish
> >
> 
> Nish,
> 
> The method I described should work for hotplug since it's using possible map
> which AFAIK is static rather than the online map. 

Oh you're right, I'm sorry!

Re: [PATCH v2] openvswitch: allocate nr_node_ids flow_stats instead of num_possible_nodes

[David Miller]

From: Chris J Arges <chris.j.arges@canonical.com>
Date: Tue, 21 Jul 2015 12:36:33 -0500

> Some architectures like POWER can have a NUMA node_possible_map that
> contains sparse entries. This causes memory corruption with openvswitch
> since it allocates flow_cache with a multiple of num_possible_nodes() and
> assumes the node variable returned by for_each_node will index into
> flow->stats[node].
> 
> Use nr_node_ids to allocate a maximal sparse array instead of
> num_possible_nodes().
> 
> The crash was noticed after 3af229f2 was applied as it changed the
> node_possible_map to match node_online_map on boot.
> Fixes: 3af229f2071f5b5cb31664be6109561fbe19c861
> 
> Signed-off-by: Chris J Arges <chris.j.arges@canonical.com>

Applied, thanks.