FAILED: patch "[PATCH] ipmr: account multicast table and route memory" failed to apply to 6.12-stable tree

The patch below does not apply to the 6.12-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-6.12.y
git checkout FETCH_HEAD
git cherry-pick -x b7ee18725f2292ab554aa96a101ae42d45f008bd
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026091603-unstuffed-goes-e540@gregkh' --subject-prefix 'PATCH 6.12.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From b7ee18725f2292ab554aa96a101ae42d45f008bd Mon Sep 17 00:00:00 2001
From: Zihan Xi <[email protected]>
Date: Tue, 8 Sep 2026 11:58:39 +0000
Subject: [PATCH] ipmr: account multicast table and route memory

A netadmin in a user+net namespace can create many IPv4 and IPv6 multicast routing tables with MRT_TABLE and MRT6_TABLE. Each unseen id allocates an mr_table via the shared mr_table_alloc(), links it into the per-net list, and leaves it until netns teardown. Those objects were not charged to memcg, so the host unreclaimable slab grows with the table count.

Account mr_table allocations with GFP_KERNEL_ACCOUNT and mark the IPv4/IPv6 MFC caches SLAB_ACCOUNT. This matches the established handling of IP addresses, routes and alternate interface names.

Unresolved MFC entries are still allocated from softIRQ with GFP_ATOMIC and are not charged. They expire after 10 seconds and are bounded by the socket receive queue; see commit 0079ad8e8dc3 ("ipmr: remove hard code cache_resolve_queue_len limit").

index e5f2b1c6150d..b9c544d48c45 100644
@@ -3376,7 +3376,8 @@ int __init ip_mr_init(void)
 {
 	int err;
 
-	mrt_cachep = KMEM_CACHE(mfc_cache, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
+	mrt_cachep = KMEM_CACHE(mfc_cache,
+				SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT);
 
 	err = register_pernet_subsys(&ipmr_net_ops);
 	if (err)

index 867b24beded1..a0ec6d19a237 100644
@@ -52,7 +52,7 @@ mr_table_alloc(struct net *net, u32 id,
 	struct mr_table *mrt;
 	int err;
 
-	mrt = kzalloc_obj(*mrt);
+	mrt = kzalloc_obj(*mrt, GFP_KERNEL_ACCOUNT);
 	if (!mrt)
 		return ERR_PTR(-ENOMEM);
 	mrt->id = id;

index 3f2ed9b77deb..9d8116b5edb1 100644
@@ -1427,7 +1427,7 @@ int __init ip6_mr_init(void)
 {
 	int err;
 
-	mrt_cachep = KMEM_CACHE(mfc6_cache, SLAB_HWCACHE_ALIGN);
+	mrt_cachep = KMEM_CACHE(mfc6_cache, SLAB_HWCACHE_ALIGN | SLAB_ACCOUNT);
 	if (!mrt_cachep)
 		return -ENOMEM;
 

From: Zihan Xi <[email protected]>

[ Upstream commit b7ee18725f2292ab554aa96a101ae42d45f008bd ]

A netadmin in a user+net namespace can create many IPv4 and IPv6 multicast routing tables with MRT_TABLE and MRT6_TABLE. Each unseen id allocates an mr_table via the shared mr_table_alloc(), links it into the per-net list, and leaves it until netns teardown. Those objects were not charged to memcg, so the host unreclaimable slab grows with the table count.

Account mr_table allocations with GFP_KERNEL_ACCOUNT and mark the IPv4/IPv6 MFC caches SLAB_ACCOUNT. This matches the established handling of IP addresses, routes and alternate interface names.

Unresolved MFC entries are still allocated from softIRQ with GFP_ATOMIC and are not charged. They expire after 10 seconds and are bounded by the socket receive queue; see commit 0079ad8e8dc3 ("ipmr: remove hard code cache_resolve_queue_len limit").

---
 net/ipv4/ipmr.c      | 3 ++-
 net/ipv4/ipmr_base.c | 2 +-
 net/ipv6/ip6mr.c     | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

index f0294b1148246..3b31189fea883 100644
@@ -3159,7 +3159,8 @@ int __init ip_mr_init(void)
 {
 	int err;
 
-	mrt_cachep = KMEM_CACHE(mfc_cache, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
+	mrt_cachep = KMEM_CACHE(mfc_cache,
+				SLAB_HWCACHE_ALIGN | SLAB_PANIC | SLAB_ACCOUNT);
 
 	err = register_pernet_subsys(&ipmr_net_ops);
 	if (err)

index 28d77d454d442..66fe1a253b9ff 100644
@@ -38,7 +38,7 @@ mr_table_alloc(struct net *net, u32 id,
 	struct mr_table *mrt;
 	int err;
 
-	mrt = kzalloc(sizeof(*mrt), GFP_KERNEL);
+	mrt = kzalloc(sizeof(*mrt), GFP_KERNEL_ACCOUNT);
 	if (!mrt)
 		return ERR_PTR(-ENOMEM);
 	mrt->id = id;

index 68bc518500f94..9bcd64e99f159 100644
@@ -1387,7 +1387,7 @@ int __init ip6_mr_init(void)
 {
 	int err;
 
-	mrt_cachep = KMEM_CACHE(mfc6_cache, SLAB_HWCACHE_ALIGN);
+	mrt_cachep = KMEM_CACHE(mfc6_cache, SLAB_HWCACHE_ALIGN | SLAB_ACCOUNT);
 	if (!mrt_cachep)
 		return -ENOMEM;
 

2.53.0