FAILED: patch "[PATCH] 8021q: delete cleared egress QoS mappings" failed to apply to 7.0-stable tree

PATCH New [email protected] 2 participants 3 messages May 4 – May 9

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[email protected]

author maintainer

2026-05-04 08:44 UTC #0 lore raw

The patch below does not apply to the 7.0-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-7.0.y
git checkout FETCH_HEAD
git cherry-pick -x 7dddc74af369478ba7f9bc136d0fc1dc4570cb66
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026050408-speak-purging-28a1@gregkh' --subject-prefix 'PATCH 7.0.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 7dddc74af369478ba7f9bc136d0fc1dc4570cb66 Mon Sep 17 00:00:00 2001
From: Longxuan Yu <[email protected]>
Date: Mon, 20 Apr 2026 11:18:46 +0800
Subject: [PATCH] 8021q: delete cleared egress QoS mappings

vlan_dev_set_egress_priority() currently keeps cleared egress priority mappings in the hash as tombstones. Repeated set/clear cycles with distinct skb priorities therefore accumulate mapping nodes until device teardown and leak memory.

Delete mappings when vlan_prio is cleared instead of keeping tombstones. Now that the egress mapping lists are RCU protected, the node can be unlinked safely and freed after a grace period.

Fixes 1da177e4c3f4 ("Linux-2.6.12-rc2")

Cc [email protected]

Reported-by Yifan Wu <[email protected]>

Reported-by Juefei Pu <[email protected]>

Reported-by Xin Liu <[email protected]>

Co-developed-by Yuan Tan <[email protected]>

Signed-off-by Yuan Tan <[email protected]>

Signed-off-by Longxuan Yu <[email protected]>

Signed-off-by Ren Wei <[email protected]>

Link https://patch.msgid.link/ecfa6f6ce2467a42647ff4c5221238ae85b79a59.1776647968.git.yuantan098@gmail.com open here

Signed-off-by Paolo Abeni <[email protected]>

net/8021q/vlan_dev.c +14 -6

index a5340932b657..7aa3af8b10ea 100644
@@ -172,26 +172,34 @@ int vlan_dev_set_egress_priority(const struct net_device *dev,
 				 u32 skb_prio, u16 vlan_prio)
 {
 	struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
+	struct vlan_priority_tci_mapping __rcu **mpp;
 	struct vlan_priority_tci_mapping *mp;
 	struct vlan_priority_tci_mapping *np;
 	u32 bucket = skb_prio & 0xF;
 	u32 vlan_qos = (vlan_prio << VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK;
 
 	/* See if a priority mapping exists.. */
-	mp = rtnl_dereference(vlan->egress_priority_map[bucket]);
+	mpp = &vlan->egress_priority_map[bucket];
+	mp = rtnl_dereference(*mpp);
 	while (mp) {
 		if (mp->priority == skb_prio) {
-			if (mp->vlan_qos && !vlan_qos)
+			if (!vlan_qos) {
+				rcu_assign_pointer(*mpp, rtnl_dereference(mp->next));
 				vlan->nr_egress_mappings--;
-			else if (!mp->vlan_qos && vlan_qos)
-				vlan->nr_egress_mappings++;
-			WRITE_ONCE(mp->vlan_qos, vlan_qos);
+				kfree_rcu(mp, rcu);
+			} else {
+				WRITE_ONCE(mp->vlan_qos, vlan_qos);
+			}
 			return 0;
 		}
-		mp = rtnl_dereference(mp->next);
+		mpp = &mp->next;
+		mp = rtnl_dereference(*mpp);
 	}
 
 	/* Create a new mapping then. */
+	if (!vlan_qos)
+		return 0;
+
 	np = kmalloc_obj(struct vlan_priority_tci_mapping);
 	if (!np)
 		return -ENOBUFS;

net/8021q/vlan_netlink.c +0 -4

index a5b16833e2ce..368d53ca7d87 100644
@@ -263,10 +263,6 @@ static int vlan_fill_info(struct sk_buff *skb, const struct net_device *dev)
 			for (pm = rcu_dereference_rtnl(vlan->egress_priority_map[i]); pm;
 			     pm = rcu_dereference_rtnl(pm->next)) {
 				u16 vlan_qos = READ_ONCE(pm->vlan_qos);
-
-				if (!vlan_qos)
-					continue;
-
 				m.from = pm->priority;
 				m.to   = (vlan_qos >> 13) & 0x7;
 				if (nla_put(skb, IFLA_VLAN_QOS_MAPPING,

Sasha Levin

maintainer

2026-05-09 00:49 UTC #1 lore raw

PATCH 1/2 8021q: use RCU for egress QoS mappings

From: Longxuan Yu <[email protected]>

[ Upstream commit fc69decc811b155a0ed8eef17ee940f28c4f6dbc ]

The TX fast path and reporting paths walk egress QoS mappings without RTNL. Convert the mapping lists to RCU-protected pointers, use RCU reader annotations in readers, and defer freeing mapping nodes with an embedded rcu_head.

This prepares the egress QoS mapping code for safe removal of mapping nodes in a follow-up change while preserving the current behavior.

Co-developed-by Yuan Tan <[email protected]>

Signed-off-by Yuan Tan <[email protected]>

Signed-off-by Longxuan Yu <[email protected]>

Signed-off-by Ren Wei <[email protected]>

Link https://patch.msgid.link/9136768189f8c6d3f824f476c62d2fa1111688e8.1776647968.git.yuantan098@gmail.com open here

Signed-off-by Paolo Abeni <[email protected]>

Stable-dep-of: 7dddc74af369 ("8021q: delete cleared egress QoS mappings")

Signed-off-by Sasha Levin <[email protected]>

---
 include/linux/if_vlan.h  | 25 ++++++++++++++++---------
 net/8021q/vlan_dev.c     | 31 ++++++++++++++++---------------
 net/8021q/vlan_netlink.c | 10 ++++++----
 net/8021q/vlanproc.c     | 12 ++++++++----
 4 files changed, 46 insertions(+), 32 deletions(-)

include/linux/if_vlan.h +16 -9

index e6272f9c5e42c..20cc16ea4e5ab 100644
@@ -147,11 +147,13 @@ extern __be16 vlan_dev_vlan_proto(const struct net_device *dev);
  *	@priority: skb priority
  *	@vlan_qos: vlan priority: (skb->priority << 13) & 0xE000
  *	@next: pointer to next struct
+ *	@rcu: used for deferred freeing of mapping nodes
  */
 struct vlan_priority_tci_mapping {
 	u32					priority;
 	u16					vlan_qos;
-	struct vlan_priority_tci_mapping	*next;
+	struct vlan_priority_tci_mapping __rcu	*next;
+	struct rcu_head			rcu;
 };
 
 struct proc_dir_entry;

@@ -177,7 +179,7 @@ struct vlan_dev_priv {
 	unsigned int				nr_ingress_mappings;
 	u32					ingress_priority_map[8];
 	unsigned int				nr_egress_mappings;
-	struct vlan_priority_tci_mapping	*egress_priority_map[16];
+	struct vlan_priority_tci_mapping __rcu	*egress_priority_map[16];
 
 	__be16					vlan_proto;
 	u16					vlan_id;

@@ -209,19 +211,24 @@ static inline u16
 vlan_dev_get_egress_qos_mask(struct net_device *dev, u32 skprio)
 {
 	struct vlan_priority_tci_mapping *mp;
+	u16 vlan_qos = 0;
 
-	smp_rmb(); /* coupled with smp_wmb() in vlan_dev_set_egress_priority() */
+	rcu_read_lock();
 
-	mp = vlan_dev_priv(dev)->egress_priority_map[(skprio & 0xF)];
+	mp = rcu_dereference(vlan_dev_priv(dev)->egress_priority_map[skprio & 0xF]);
 	while (mp) {
 		if (mp->priority == skprio) {
-			return mp->vlan_qos; /* This should already be shifted
-					      * to mask correctly with the
-					      * VLAN's TCI */
+			vlan_qos = READ_ONCE(mp->vlan_qos);
+			break;
 		}
-		mp = mp->next;
+		mp = rcu_dereference(mp->next);
 	}
-	return 0;
+	rcu_read_unlock();
+
+	/* This should already be shifted to mask correctly with
+	 * the VLAN's TCI.
+	 */
+	return vlan_qos;
 }
 
 extern bool vlan_do_receive(struct sk_buff **skb);

net/8021q/vlan_dev.c +16 ~~-15~~

index c40f7d5c4fca5..a5340932b657a 100644
@@ -172,39 +172,34 @@ int vlan_dev_set_egress_priority(const struct net_device *dev,
 				 u32 skb_prio, u16 vlan_prio)
 {
 	struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
-	struct vlan_priority_tci_mapping *mp = NULL;
+	struct vlan_priority_tci_mapping *mp;
 	struct vlan_priority_tci_mapping *np;
+	u32 bucket = skb_prio & 0xF;
 	u32 vlan_qos = (vlan_prio << VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK;
 
 	/* See if a priority mapping exists.. */
-	mp = vlan->egress_priority_map[skb_prio & 0xF];
+	mp = rtnl_dereference(vlan->egress_priority_map[bucket]);
 	while (mp) {
 		if (mp->priority == skb_prio) {
 			if (mp->vlan_qos && !vlan_qos)
 				vlan->nr_egress_mappings--;
 			else if (!mp->vlan_qos && vlan_qos)
 				vlan->nr_egress_mappings++;
-			mp->vlan_qos = vlan_qos;
+			WRITE_ONCE(mp->vlan_qos, vlan_qos);
 			return 0;
 		}
-		mp = mp->next;
+		mp = rtnl_dereference(mp->next);
 	}
 
 	/* Create a new mapping then. */
-	mp = vlan->egress_priority_map[skb_prio & 0xF];
 	np = kmalloc_obj(struct vlan_priority_tci_mapping);
 	if (!np)
 		return -ENOBUFS;
 
-	np->next = mp;
 	np->priority = skb_prio;
 	np->vlan_qos = vlan_qos;
-	/* Before inserting this element in hash table, make sure all its fields
-	 * are committed to memory.
-	 * coupled with smp_rmb() in vlan_dev_get_egress_qos_mask()
-	 */
-	smp_wmb();
-	vlan->egress_priority_map[skb_prio & 0xF] = np;
+	RCU_INIT_POINTER(np->next, rtnl_dereference(vlan->egress_priority_map[bucket]));
+	rcu_assign_pointer(vlan->egress_priority_map[bucket], np);
 	if (vlan_qos)
 		vlan->nr_egress_mappings++;
 	return 0;

@@ -604,11 +599,17 @@ void vlan_dev_free_egress_priority(const struct net_device *dev)
 	int i;
 
 	for (i = 0; i < ARRAY_SIZE(vlan->egress_priority_map); i++) {
-		while ((pm = vlan->egress_priority_map[i]) != NULL) {
-			vlan->egress_priority_map[i] = pm->next;
-			kfree(pm);
+		pm = rtnl_dereference(vlan->egress_priority_map[i]);
+		RCU_INIT_POINTER(vlan->egress_priority_map[i], NULL);
+		while (pm) {
+			struct vlan_priority_tci_mapping *next;
+
+			next = rtnl_dereference(pm->next);
+			kfree_rcu(pm, rcu);
+			pm = next;
 		}
 	}
+	vlan->nr_egress_mappings = 0;
 }
 
 static void vlan_dev_uninit(struct net_device *dev)

net/8021q/vlan_netlink.c +6 -4

index a000b1ef05206..a5b16833e2cee 100644
@@ -260,13 +260,15 @@ static int vlan_fill_info(struct sk_buff *skb, const struct net_device *dev)
 			goto nla_put_failure;
 
 		for (i = 0; i < ARRAY_SIZE(vlan->egress_priority_map); i++) {
-			for (pm = vlan->egress_priority_map[i]; pm;
-			     pm = pm->next) {
-				if (!pm->vlan_qos)
+			for (pm = rcu_dereference_rtnl(vlan->egress_priority_map[i]); pm;
+			     pm = rcu_dereference_rtnl(pm->next)) {
+				u16 vlan_qos = READ_ONCE(pm->vlan_qos);
+
+				if (!vlan_qos)
 					continue;
 
 				m.from = pm->priority;
-				m.to   = (pm->vlan_qos >> 13) & 0x7;
+				m.to   = (vlan_qos >> 13) & 0x7;
 				if (nla_put(skb, IFLA_VLAN_QOS_MAPPING,
 					    sizeof(m), &m))
 					goto nla_put_failure;

net/8021q/vlanproc.c +8 -4

index fa67374bda494..0e424e0895b7e 100644
@@ -262,15 +262,19 @@ static int vlandev_seq_show(struct seq_file *seq, void *offset)
 		   vlan->ingress_priority_map[7]);
 
 	seq_printf(seq, " EGRESS priority mappings: ");
+	rcu_read_lock();
 	for (i = 0; i < 16; i++) {
-		const struct vlan_priority_tci_mapping *mp
-			= vlan->egress_priority_map[i];
+		const struct vlan_priority_tci_mapping *mp =
+			rcu_dereference(vlan->egress_priority_map[i]);
 		while (mp) {
+			u16 vlan_qos = READ_ONCE(mp->vlan_qos);
+
 			seq_printf(seq, "%u:%d ",
-				   mp->priority, ((mp->vlan_qos >> 13) & 0x7));
-			mp = mp->next;
+				   mp->priority, ((vlan_qos >> 13) & 0x7));
+			mp = rcu_dereference(mp->next);
 		}
 	}
+	rcu_read_unlock();
 	seq_puts(seq, "\n");
 
 	return 0;

Signature · 1 line

2.53.0

Sasha Levin

maintainer

2026-05-09 00:49 UTC #2 lore raw

PATCH 2/2 8021q: delete cleared egress QoS mappings

From: Longxuan Yu <[email protected]>

[ Upstream commit 7dddc74af369478ba7f9bc136d0fc1dc4570cb66 ]

Delete mappings when vlan_prio is cleared instead of keeping tombstones. Now that the egress mapping lists are RCU protected, the node can be unlinked safely and freed after a grace period.

Fixes 1da177e4c3f4 ("Linux-2.6.12-rc2")

Cc [email protected]

Reported-by Yifan Wu <[email protected]>

Reported-by Juefei Pu <[email protected]>

Reported-by Xin Liu <[email protected]>

Co-developed-by Yuan Tan <[email protected]>

Signed-off-by Yuan Tan <[email protected]>

Signed-off-by Longxuan Yu <[email protected]>

Signed-off-by Ren Wei <[email protected]>

Link https://patch.msgid.link/ecfa6f6ce2467a42647ff4c5221238ae85b79a59.1776647968.git.yuantan098@gmail.com open here

Signed-off-by Paolo Abeni <[email protected]>

Signed-off-by Sasha Levin <[email protected]>

---
 net/8021q/vlan_dev.c     | 20 ++++++++++++++------
 net/8021q/vlan_netlink.c |  4 ----
 2 files changed, 14 insertions(+), 10 deletions(-)

net/8021q/vlan_dev.c +14 -6

index a5340932b657a..7aa3af8b10ead 100644
@@ -172,26 +172,34 @@ int vlan_dev_set_egress_priority(const struct net_device *dev,
 				 u32 skb_prio, u16 vlan_prio)
 {
 	struct vlan_dev_priv *vlan = vlan_dev_priv(dev);
+	struct vlan_priority_tci_mapping __rcu **mpp;
 	struct vlan_priority_tci_mapping *mp;
 	struct vlan_priority_tci_mapping *np;
 	u32 bucket = skb_prio & 0xF;
 	u32 vlan_qos = (vlan_prio << VLAN_PRIO_SHIFT) & VLAN_PRIO_MASK;
 
 	/* See if a priority mapping exists.. */
-	mp = rtnl_dereference(vlan->egress_priority_map[bucket]);
+	mpp = &vlan->egress_priority_map[bucket];
+	mp = rtnl_dereference(*mpp);
 	while (mp) {
 		if (mp->priority == skb_prio) {
-			if (mp->vlan_qos && !vlan_qos)
+			if (!vlan_qos) {
+				rcu_assign_pointer(*mpp, rtnl_dereference(mp->next));
 				vlan->nr_egress_mappings--;
-			else if (!mp->vlan_qos && vlan_qos)
-				vlan->nr_egress_mappings++;
-			WRITE_ONCE(mp->vlan_qos, vlan_qos);
+				kfree_rcu(mp, rcu);
+			} else {
+				WRITE_ONCE(mp->vlan_qos, vlan_qos);
+			}
 			return 0;
 		}
-		mp = rtnl_dereference(mp->next);
+		mpp = &mp->next;
+		mp = rtnl_dereference(*mpp);
 	}
 
 	/* Create a new mapping then. */
+	if (!vlan_qos)
+		return 0;
+
 	np = kmalloc_obj(struct vlan_priority_tci_mapping);
 	if (!np)
 		return -ENOBUFS;

net/8021q/vlan_netlink.c +0 -4

index a5b16833e2cee..368d53ca7d870 100644
@@ -263,10 +263,6 @@ static int vlan_fill_info(struct sk_buff *skb, const struct net_device *dev)
 			for (pm = rcu_dereference_rtnl(vlan->egress_priority_map[i]); pm;
 			     pm = rcu_dereference_rtnl(pm->next)) {
 				u16 vlan_qos = READ_ONCE(pm->vlan_qos);
-
-				if (!vlan_qos)
-					continue;
-
 				m.from = pm->priority;
 				m.to   = (vlan_qos >> 13) & 0x7;
 				if (nla_put(skb, IFLA_VLAN_QOS_MAPPING,

Signature · 1 line

2.53.0