diff options
| -rw-r--r-- | include/net/sock.h | 22 | ||||
| -rw-r--r-- | mm/memcontrol.c | 31 | ||||
| -rw-r--r-- | net/ipv4/tcp_memcontrol.c | 34 |
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; } |