From 2f8c295b41473b62dcca379f76fa6608cee9c5d2 Mon Sep 17 00:00:00 2001 From: Shakeel Butt Date: Thu, 16 Oct 2025 09:10:35 -0700 Subject: [PATCH] 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 Acked-by: Roman Gushchin Reviewed-by: Kuniyuki Iwashima Reviewed-by: Daniel Sedlak Cc: David S. Miller Cc: Eric Dumazet Cc: Jakub Kacinski Cc: Johannes Weiner Cc: Michal Hocko Cc: Muchun Song Cc: Neal Cardwell Cc: Paolo Abeni Cc: Simon Horman Cc: Tejun Heo Cc: Willem de Bruijn Signed-off-by: Andrew Morton --- Documentation/admin-guide/cgroup-v2.rst | 4 ++++ include/linux/memcontrol.h | 1 + include/net/sock.h | 6 +++++- kernel/cgroup/cgroup.c | 1 + mm/memcontrol.c | 3 +++ 5 files changed, 14 insertions(+), 1 deletion(-) diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst index 0e6c67ac585a..3345961c30ac 100644 --- a/Documentation/admin-guide/cgroup-v2.rst +++ b/Documentation/admin-guide/cgroup-v2.rst @@ -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 diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 5ca97fece690..d37e7c93bb8c 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -52,6 +52,7 @@ enum memcg_memory_event { MEMCG_SWAP_HIGH, MEMCG_SWAP_MAX, MEMCG_SWAP_FAIL, + MEMCG_SOCK_THROTTLED, MEMCG_NR_MEMORY_EVENTS, }; diff --git a/include/net/sock.h b/include/net/sock.h index 60bcb13f045c..ff7d49af1619 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -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; diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 6ae5f48cf64e..351e9af14ad7 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -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 diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 75d1715628f7..1a95049d8b88 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -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); @@ -4464,6 +4465,8 @@ 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) -- 2.51.0