Thread (10 messages) 10 messages, 2 authors, 2025-06-11
STALE408d

[PATCH net 3/3] Revert "openvswitch: Merge three per-CPU structures into one"

From: Gal Pressman <hidden>
Date: 2025-06-10 06:27:08
Also in: linux-rt-devel
Subsystem: networking [general], openvswitch, the rest · Maintainers: "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Aaron Conole, Eelco Chaudron, Ilya Maximets, Linus Torvalds

This reverts commit 035fcdc4d240c873c89b76b752dd9921bc88c1ba.

The cited commit changed openvswitch to use static percpu allocations,
and exhausted the reserved chunk on module init.
Allocation of struct ovs_pcpu_storage (6488 bytes) fails on ARM:

percpu: allocation failed, size=6488 align=8 atomic=0, alloc from reserved chunk failed
CPU: 2 UID: 0 PID: 4571 Comm: modprobe Not tainted 6.15.0-for-upstream-bluefield-2025-05-28-15-45 #1 NONE
Hardware name: https://www.mellanox.com BlueField SoC/BlueField SoC, BIOS 4.9.0.13378 Oct 30 2024
Call trace:
 show_stack+0x20/0x38 (C)
 dump_stack_lvl+0x80/0xf8
 dump_stack+0x18/0x28
 pcpu_alloc_noprof+0x860/0xa48
 load_module+0xc68/0x23f0
 init_module_from_file+0x90/0xe0
 __arm64_sys_finit_module+0x21c/0x3d8
 invoke_syscall+0x50/0x120
 el0_svc_common.constprop.0+0x48/0xf0
 do_el0_svc+0x24/0x38
 el0_svc+0x34/0xf0
 el0t_64_sync_handler+0x10c/0x138
 el0t_64_sync+0x1ac/0x1b0
openvswitch: Could not allocate 6488 bytes percpu data

For large buffers, dynamic allocations are preferred, revert the patch.

Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Gal Pressman <redacted>
---
 net/openvswitch/actions.c  | 49 +++++++++++++++++++++++++-------------
 net/openvswitch/datapath.c |  9 ++++++-
 net/openvswitch/datapath.h |  3 +++
 3 files changed, 44 insertions(+), 17 deletions(-)
diff --git a/net/openvswitch/actions.c b/net/openvswitch/actions.c
index 7e4a8d41b9ed..2f22ca59586f 100644
--- a/net/openvswitch/actions.c
+++ b/net/openvswitch/actions.c
@@ -78,22 +78,17 @@ struct action_flow_keys {
 	struct sw_flow_key key[OVS_DEFERRED_ACTION_THRESHOLD];
 };
 
-struct ovs_pcpu_storage {
-	struct action_fifo action_fifos;
-	struct action_flow_keys flow_keys;
-	int exec_level;
-};
-
-static DEFINE_PER_CPU(struct ovs_pcpu_storage, ovs_pcpu_storage);
+static struct action_fifo __percpu *action_fifos;
+static struct action_flow_keys __percpu *flow_keys;
+static DEFINE_PER_CPU(int, exec_actions_level);
 
 /* Make a clone of the 'key', using the pre-allocated percpu 'flow_keys'
  * space. Return NULL if out of key spaces.
  */
 static struct sw_flow_key *clone_key(const struct sw_flow_key *key_)
 {
-	struct ovs_pcpu_storage *ovs_pcpu = this_cpu_ptr(&ovs_pcpu_storage);
-	struct action_flow_keys *keys = &ovs_pcpu->flow_keys;
-	int level = ovs_pcpu->exec_level;
+	struct action_flow_keys *keys = this_cpu_ptr(flow_keys);
+	int level = this_cpu_read(exec_actions_level);
 	struct sw_flow_key *key = NULL;
 
 	if (level <= OVS_DEFERRED_ACTION_THRESHOLD) {
@@ -137,9 +132,10 @@ static struct deferred_action *add_deferred_actions(struct sk_buff *skb,
 				    const struct nlattr *actions,
 				    const int actions_len)
 {
-	struct action_fifo *fifo = this_cpu_ptr(&ovs_pcpu_storage.action_fifos);
+	struct action_fifo *fifo;
 	struct deferred_action *da;
 
+	fifo = this_cpu_ptr(action_fifos);
 	da = action_fifo_put(fifo);
 	if (da) {
 		da->skb = skb;
@@ -1612,13 +1608,13 @@ static int clone_execute(struct datapath *dp, struct sk_buff *skb,
 
 		if (actions) { /* Sample action */
 			if (clone_flow_key)
-				__this_cpu_inc(ovs_pcpu_storage.exec_level);
+				__this_cpu_inc(exec_actions_level);
 
 			err = do_execute_actions(dp, skb, clone,
 						 actions, len);
 
 			if (clone_flow_key)
-				__this_cpu_dec(ovs_pcpu_storage.exec_level);
+				__this_cpu_dec(exec_actions_level);
 		} else { /* Recirc action */
 			clone->recirc_id = recirc_id;
 			ovs_dp_process_packet(skb, clone);
@@ -1654,7 +1650,7 @@ static int clone_execute(struct datapath *dp, struct sk_buff *skb,
 
 static void process_deferred_actions(struct datapath *dp)
 {
-	struct action_fifo *fifo = this_cpu_ptr(&ovs_pcpu_storage.action_fifos);
+	struct action_fifo *fifo = this_cpu_ptr(action_fifos);
 
 	/* Do not touch the FIFO in case there is no deferred actions. */
 	if (action_fifo_is_empty(fifo))
@@ -1685,7 +1681,7 @@ int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb,
 {
 	int err, level;
 
-	level = __this_cpu_inc_return(ovs_pcpu_storage.exec_level);
+	level = __this_cpu_inc_return(exec_actions_level);
 	if (unlikely(level > OVS_RECURSION_LIMIT)) {
 		net_crit_ratelimited("ovs: recursion limit reached on datapath %s, probable configuration error\n",
 				     ovs_dp_name(dp));
@@ -1702,6 +1698,27 @@ int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb,
 		process_deferred_actions(dp);
 
 out:
-	__this_cpu_dec(ovs_pcpu_storage.exec_level);
+	__this_cpu_dec(exec_actions_level);
 	return err;
 }
+
+int action_fifos_init(void)
+{
+	action_fifos = alloc_percpu(struct action_fifo);
+	if (!action_fifos)
+		return -ENOMEM;
+
+	flow_keys = alloc_percpu(struct action_flow_keys);
+	if (!flow_keys) {
+		free_percpu(action_fifos);
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+void action_fifos_exit(void)
+{
+	free_percpu(action_fifos);
+	free_percpu(flow_keys);
+}
diff --git a/net/openvswitch/datapath.c b/net/openvswitch/datapath.c
index aaa6277bb49c..5d548eda742d 100644
--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -2729,10 +2729,14 @@ static int __init dp_init(void)
 
 	pr_info("Open vSwitch switching datapath\n");
 
-	err = ovs_internal_dev_rtnl_link_register();
+	err = action_fifos_init();
 	if (err)
 		goto error;
 
+	err = ovs_internal_dev_rtnl_link_register();
+	if (err)
+		goto error_action_fifos_exit;
+
 	err = ovs_flow_init();
 	if (err)
 		goto error_unreg_rtnl_link;
@@ -2774,6 +2778,8 @@ static int __init dp_init(void)
 	ovs_flow_exit();
 error_unreg_rtnl_link:
 	ovs_internal_dev_rtnl_link_unregister();
+error_action_fifos_exit:
+	action_fifos_exit();
 error:
 	return err;
 }
@@ -2789,6 +2795,7 @@ static void dp_cleanup(void)
 	ovs_vport_exit();
 	ovs_flow_exit();
 	ovs_internal_dev_rtnl_link_unregister();
+	action_fifos_exit();
 }
 
 module_init(dp_init);
diff --git a/net/openvswitch/datapath.h b/net/openvswitch/datapath.h
index a12640792605..384ca77f4e79 100644
--- a/net/openvswitch/datapath.h
+++ b/net/openvswitch/datapath.h
@@ -281,6 +281,9 @@ int ovs_execute_actions(struct datapath *dp, struct sk_buff *skb,
 
 void ovs_dp_notify_wq(struct work_struct *work);
 
+int action_fifos_init(void);
+void action_fifos_exit(void);
+
 /* 'KEY' must not have any bits set outside of the 'MASK' */
 #define OVS_MASKED(OLD, KEY, MASK) ((KEY) | ((OLD) & ~(MASK)))
 #define OVS_SET_MASKED(OLD, KEY, MASK) ((OLD) = OVS_MASKED(OLD, KEY, MASK))
-- 
2.40.1
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