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-rw-r--r--include/net/sock.h22
-rw-r--r--mm/memcontrol.c31
-rw-r--r--net/ipv4/tcp_memcontrol.c34
3 files changed, 78 insertions, 9 deletions
diff --git a/include/net/sock.h b/include/net/sock.h
index d89f0582b6b6..4a4521699563 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -46,6 +46,7 @@
#include <linux/list_nulls.h>
#include <linux/timer.h>
#include <linux/cache.h>
+#include <linux/bitops.h>
#include <linux/lockdep.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h> /* struct sk_buff */
@@ -921,12 +922,23 @@ struct proto {
#endif
};
+/*
+ * Bits in struct cg_proto.flags
+ */
+enum cg_proto_flags {
+ /* Currently active and new sockets should be assigned to cgroups */
+ MEMCG_SOCK_ACTIVE,
+ /* It was ever activated; we must disarm static keys on destruction */
+ MEMCG_SOCK_ACTIVATED,
+};
+
struct cg_proto {
void (*enter_memory_pressure)(struct sock *sk);
struct res_counter *memory_allocated; /* Current allocated memory. */
struct percpu_counter *sockets_allocated; /* Current number of sockets. */
int *memory_pressure;
long *sysctl_mem;
+ unsigned long flags;
/*
* memcg field is used to find which memcg we belong directly
* Each memcg struct can hold more than one cg_proto, so container_of
@@ -942,6 +954,16 @@ struct cg_proto {
extern int proto_register(struct proto *prot, int alloc_slab);
extern void proto_unregister(struct proto *prot);
+static inline bool memcg_proto_active(struct cg_proto *cg_proto)
+{
+ return test_bit(MEMCG_SOCK_ACTIVE, &cg_proto->flags);
+}
+
+static inline bool memcg_proto_activated(struct cg_proto *cg_proto)
+{
+ return test_bit(MEMCG_SOCK_ACTIVATED, &cg_proto->flags);
+}
+
#ifdef SOCK_REFCNT_DEBUG
static inline void sk_refcnt_debug_inc(struct sock *sk)
{
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6fbf50977f77..ac35bccadb7b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -417,6 +417,7 @@ void sock_update_memcg(struct sock *sk)
{
if (mem_cgroup_sockets_enabled) {
struct mem_cgroup *memcg;
+ struct cg_proto *cg_proto;
BUG_ON(!sk->sk_prot->proto_cgroup);
@@ -436,9 +437,10 @@ void sock_update_memcg(struct sock *sk)
rcu_read_lock();
memcg = mem_cgroup_from_task(current);
- if (!mem_cgroup_is_root(memcg)) {
+ cg_proto = sk->sk_prot->proto_cgroup(memcg);
+ if (!mem_cgroup_is_root(memcg) && memcg_proto_active(cg_proto)) {
mem_cgroup_get(memcg);
- sk->sk_cgrp = sk->sk_prot->proto_cgroup(memcg);
+ sk->sk_cgrp = cg_proto;
}
rcu_read_unlock();
}
@@ -467,6 +469,19 @@ EXPORT_SYMBOL(tcp_proto_cgroup);
#endif /* CONFIG_INET */
#endif /* CONFIG_CGROUP_MEM_RES_CTLR_KMEM */
+#if defined(CONFIG_INET) && defined(CONFIG_CGROUP_MEM_RES_CTLR_KMEM)
+static void disarm_sock_keys(struct mem_cgroup *memcg)
+{
+ if (!memcg_proto_activated(&memcg->tcp_mem.cg_proto))
+ return;
+ static_key_slow_dec(&memcg_socket_limit_enabled);
+}
+#else
+static void disarm_sock_keys(struct mem_cgroup *memcg)
+{
+}
+#endif
+
static void drain_all_stock_async(struct mem_cgroup *memcg);
static struct mem_cgroup_per_zone *
@@ -4712,6 +4727,18 @@ static void free_work(struct work_struct *work)
int size = sizeof(struct mem_cgroup);
memcg = container_of(work, struct mem_cgroup, work_freeing);
+ /*
+ * We need to make sure that (at least for now), the jump label
+ * destruction code runs outside of the cgroup lock. This is because
+ * get_online_cpus(), which is called from the static_branch update,
+ * can't be called inside the cgroup_lock. cpusets are the ones
+ * enforcing this dependency, so if they ever change, we might as well.
+ *
+ * schedule_work() will guarantee this happens. Be careful if you need
+ * to move this code around, and make sure it is outside
+ * the cgroup_lock.
+ */
+ disarm_sock_keys(memcg);
if (size < PAGE_SIZE)
kfree(memcg);
else
diff --git a/net/ipv4/tcp_memcontrol.c b/net/ipv4/tcp_memcontrol.c
index 151703791bb0..b6f3583ddfe8 100644
--- a/net/ipv4/tcp_memcontrol.c
+++ b/net/ipv4/tcp_memcontrol.c
@@ -74,9 +74,6 @@ void tcp_destroy_cgroup(struct mem_cgroup *memcg)
percpu_counter_destroy(&tcp->tcp_sockets_allocated);
val = res_counter_read_u64(&tcp->tcp_memory_allocated, RES_LIMIT);
-
- if (val != RESOURCE_MAX)
- static_key_slow_dec(&memcg_socket_limit_enabled);
}
EXPORT_SYMBOL(tcp_destroy_cgroup);
@@ -107,10 +104,33 @@ static int tcp_update_limit(struct mem_cgroup *memcg, u64 val)
tcp->tcp_prot_mem[i] = min_t(long, val >> PAGE_SHIFT,
net->ipv4.sysctl_tcp_mem[i]);
- if (val == RESOURCE_MAX && old_lim != RESOURCE_MAX)
- static_key_slow_dec(&memcg_socket_limit_enabled);
- else if (old_lim == RESOURCE_MAX && val != RESOURCE_MAX)
- static_key_slow_inc(&memcg_socket_limit_enabled);
+ if (val == RESOURCE_MAX)
+ clear_bit(MEMCG_SOCK_ACTIVE, &cg_proto->flags);
+ else if (val != RESOURCE_MAX) {
+ /*
+ * The active bit needs to be written after the static_key
+ * update. This is what guarantees that the socket activation
+ * function is the last one to run. See sock_update_memcg() for
+ * details, and note that we don't mark any socket as belonging
+ * to this memcg until that flag is up.
+ *
+ * We need to do this, because static_keys will span multiple
+ * sites, but we can't control their order. If we mark a socket
+ * as accounted, but the accounting functions are not patched in
+ * yet, we'll lose accounting.
+ *
+ * We never race with the readers in sock_update_memcg(),
+ * because when this value change, the code to process it is not
+ * patched in yet.
+ *
+ * The activated bit is used to guarantee that no two writers
+ * will do the update in the same memcg. Without that, we can't
+ * properly shutdown the static key.
+ */
+ if (!test_and_set_bit(MEMCG_SOCK_ACTIVATED, &cg_proto->flags))
+ static_key_slow_inc(&memcg_socket_limit_enabled);
+ set_bit(MEMCG_SOCK_ACTIVE, &cg_proto->flags);
+ }
return 0;
}