Commit d929525c authored Oct 16, 2025 by Shakeel Butt Committed by Andrew Morton Nov 16, 2025

memcg: net: track network throttling due to memcg memory pressure

The kernel can throttle network sockets if the memory cgroup associated
with the corresponding socket is under memory pressure.  The throttling
actions include clamping the transmit window, failing to expand receive or
send buffers, aggressively prune out-of-order receive queue, FIN deferred
to a retransmitted packet and more.  Let's add memcg metric to track such
throttling actions.

At the moment memcg memory pressure is defined through vmpressure and in
future it may be defined using PSI or we may add more flexible way for the
users to define memory pressure, maybe through ebpf.  However the
potential throttling actions will remain the same, so this newly
introduced metric will continue to track throttling actions irrespective
of how memcg memory pressure is defined.

Link: https://lkml.kernel.org/r/20251016161035.86161-1-shakeel.butt@linux.dev


Signed-off-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Daniel Sedlak <daniel.sedlak@cdn77.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Jakub Kacinski <kuba@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Paolo Abeni <pabeni@redhat.com>
Cc: Simon Horman <horms@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Willem de Bruijn <willemb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent a059ad48

Documentation/admin-guide/cgroup-v2.rst

+4 −0

Original line number	Diff line number	Diff line
		@@ -1515,6 +1515,10 @@ The following nested keys are defined.
		oom_group_kill
		The number of times a group OOM has occurred.

		sock_throttled
		The number of times network sockets associated with
		this cgroup are throttled.

		memory.events.local
		Similar to memory.events but the fields in the file are local
		to the cgroup i.e. not hierarchical. The file modified event

include/linux/memcontrol.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -52,6 +52,7 @@ enum memcg_memory_event {
		MEMCG_SWAP_HIGH,
		MEMCG_SWAP_MAX,
		MEMCG_SWAP_FAIL,
		MEMCG_SOCK_THROTTLED,
		MEMCG_NR_MEMORY_EVENTS,
		};

include/net/sock.h

+5 −1

Original line number	Diff line number	Diff line
		@@ -2635,8 +2635,12 @@ static inline bool mem_cgroup_sk_under_memory_pressure(const struct sock *sk)
		#endif /* CONFIG_MEMCG_V1 */

		do {
		if (time_before64(get_jiffies_64(), mem_cgroup_get_socket_pressure(memcg)))
		if (time_before64(get_jiffies_64(),
		mem_cgroup_get_socket_pressure(memcg))) {
		memcg_memory_event(mem_cgroup_from_sk(sk),
		MEMCG_SOCK_THROTTLED);
		return true;
		}
		} while ((memcg = parent_mem_cgroup(memcg)));

		return false;

kernel/cgroup/cgroup.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -4704,6 +4704,7 @@ void cgroup_file_notify(struct cgroup_file *cfile)
		}
		spin_unlock_irqrestore(&cgroup_file_kn_lock, flags);
		}
		EXPORT_SYMBOL_GPL(cgroup_file_notify);

		/**
		* cgroup_file_show - show or hide a hidden cgroup file

mm/memcontrol.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -81,6 +81,7 @@ struct cgroup_subsys memory_cgrp_subsys __read_mostly;
		EXPORT_SYMBOL(memory_cgrp_subsys);

		struct mem_cgroup *root_mem_cgroup __read_mostly;
		EXPORT_SYMBOL(root_mem_cgroup);

		/* Active memory cgroup to use from an interrupt context */
		DEFINE_PER_CPU(struct mem_cgroup *, int_active_memcg);
		@@ -4463,6 +4464,8 @@ static void __memory_events_show(struct seq_file m, atomic_long_t events)
		atomic_long_read(&events[MEMCG_OOM_KILL]));
		seq_printf(m, "oom_group_kill %lu\n",
		atomic_long_read(&events[MEMCG_OOM_GROUP_KILL]));
		seq_printf(m, "sock_throttled %lu\n",
		atomic_long_read(&events[MEMCG_SOCK_THROTTLED]));
		}

		static int memory_events_show(struct seq_file m, void v)