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ipmr: account multicast table and route memory

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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 0079ad8e8d
("ipmr: remove hard code cache_resolve_queue_len limit").

Fixes: f0ad0860d0 ("ipv4: ipmr: support multiple tables")
Fixes: d1db275dd3 ("ipv6: ip6mr: support multiple tables")
Cc: stable@vger.kernel.org
Reported-by: Vega <vega@nebusec.ai>
Signed-off-by: Zihan Xi <zihanx@nebusec.ai>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/050b58f7fc6b45da0fb12768ebb62d18fa46133d.1788784801.git.zihanx@nebusec.ai
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Zihan Xi 2026-09-08 11:58:39 +00:00 committed by Jakub Kicinski
parent 6ca81bbc31
commit b7ee18725f
3 changed files with 4 additions and 3 deletions
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3
net/ipv4/ipmr.c
View File

@ -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)

2
net/ipv4/ipmr_base.c
View File

@ -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;

2
net/ipv6/ip6mr.c
View File

@ -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;