diff options
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 192 |
1 files changed, 185 insertions, 7 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 53b8201b31eb..669d16ac56dc 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -310,14 +310,31 @@ struct mem_cgroup { /* thresholds for mem+swap usage. RCU-protected */ struct mem_cgroup_thresholds memsw_thresholds; - /* For oom notifier event fd */ - struct list_head oom_notify; + union { + /* For oom notifier event fd */ + struct list_head oom_notify; + /* + * we can only trigger an oom event if the memcg is alive. + * so we will reuse this field to hook the memcg in the list + * of dead memcgs. + */ + struct list_head dead; + }; - /* - * Should we move charges of a task when a task is moved into this - * mem_cgroup ? And what type of charges should we move ? - */ - unsigned long move_charge_at_immigrate; + union { + /* + * Should we move charges of a task when a task is moved into + * this mem_cgroup ? And what type of charges should we move ? + */ + unsigned long move_charge_at_immigrate; + + /* + * We are no longer concerned about moving charges after memcg + * is dead. So we will fill this up with its name, to aid + * debugging. + */ + char *memcg_name; + }; /* * set > 0 if pages under this cgroup are moving to other cgroup. */ @@ -369,6 +386,55 @@ static size_t memcg_size(void) nr_node_ids * sizeof(struct mem_cgroup_per_node); } +#ifdef CONFIG_MEMCG_DEBUG_ASYNC_DESTROY +static LIST_HEAD(dangling_memcgs); +static DEFINE_MUTEX(dangling_memcgs_mutex); + +static inline void memcg_dangling_free(struct mem_cgroup *memcg) +{ + mutex_lock(&dangling_memcgs_mutex); + list_del(&memcg->dead); + mutex_unlock(&dangling_memcgs_mutex); + free_pages((unsigned long)memcg->memcg_name, 0); +} + +static inline void memcg_dangling_add(struct mem_cgroup *memcg) +{ + /* + * cgroup.c will do page-sized allocations most of the time, + * so we'll just follow the pattern. Also, __get_free_pages + * is a better interface than kmalloc for us here, because + * we'd like this memory to be always billed to the root cgroup, + * not to the process removing the memcg. While kmalloc would + * require us to wrap it into memcg_stop/resume_kmem_account, + * with __get_free_pages we just don't pass the memcg flag. + */ + memcg->memcg_name = (char *)__get_free_pages(GFP_KERNEL, 0); + + /* + * we will, in general, just ignore failures. No need to go crazy, + * being this just a debugging interface. It is nice to copy a memcg + * name over, but if we (unlikely) can't, just the address will do + */ + if (!memcg->memcg_name) + goto add_list; + + if (cgroup_path(memcg->css.cgroup, memcg->memcg_name, PAGE_SIZE) < 0) { + free_pages((unsigned long)memcg->memcg_name, 0); + memcg->memcg_name = NULL; + } + +add_list: + INIT_LIST_HEAD(&memcg->dead); + mutex_lock(&dangling_memcgs_mutex); + list_add(&memcg->dead, &dangling_memcgs); + mutex_unlock(&dangling_memcgs_mutex); +} +#else +static inline void memcg_dangling_free(struct mem_cgroup *memcg) {} +static inline void memcg_dangling_add(struct mem_cgroup *memcg) {} +#endif + /* internal only representation about the status of kmem accounting. */ enum { KMEM_ACCOUNTED_ACTIVE = 0, /* accounted by this cgroup itself */ @@ -4970,6 +5036,107 @@ static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft, return simple_read_from_buffer(buf, nbytes, ppos, str, len); } +#ifdef CONFIG_MEMCG_DEBUG_ASYNC_DESTROY +static void +mem_cgroup_dangling_swap(struct mem_cgroup *memcg, struct seq_file *m) +{ +#ifdef CONFIG_MEMCG_SWAP + u64 kmem; + u64 memsw; + + /* + * kmem will also propagate here, so we are only interested in the + * difference. See comment in mem_cgroup_reparent_charges for details. + * + * We could save this value for later consumption by kmem reports, but + * there is not a lot of problem if the figures differ slightly. + */ + kmem = res_counter_read_u64(&memcg->kmem, RES_USAGE); + memsw = res_counter_read_u64(&memcg->memsw, RES_USAGE) - kmem; + seq_printf(m, "\t%llu swap bytes\n", memsw); +#endif +} + + +static void +mem_cgroup_dangling_tcp(struct mem_cgroup *memcg, struct seq_file *m) +{ +#if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM) + struct tcp_memcontrol *tcp = &memcg->tcp_mem; + s64 tcp_socks; + u64 tcp_bytes; + + tcp_socks = percpu_counter_sum_positive(&tcp->tcp_sockets_allocated); + tcp_bytes = res_counter_read_u64(&tcp->tcp_memory_allocated, RES_USAGE); + seq_printf(m, "\t%llu tcp bytes", tcp_bytes); + /* + * if tcp_bytes == 0, tcp_socks != 0 is a bug. One more reason to print + * it! + */ + if (tcp_bytes || tcp_socks) + seq_printf(m, ", in %lld sockets", tcp_socks); + seq_printf(m, "\n"); + +#endif +} + +static void +mem_cgroup_dangling_kmem(struct mem_cgroup *memcg, struct seq_file *m) +{ +#ifdef CONFIG_MEMCG_KMEM + u64 kmem; + struct memcg_cache_params *params; + + kmem = res_counter_read_u64(&memcg->kmem, RES_USAGE); + seq_printf(m, "\t%llu kmem bytes", kmem); + + /* list below may not be initialized, so not even try */ + if (!kmem) + return; + + seq_printf(m, " in caches"); + mutex_lock(&memcg->slab_caches_mutex); + list_for_each_entry(params, &memcg->memcg_slab_caches, list) { + struct kmem_cache *s = memcg_params_to_cache(params); + + seq_printf(m, " %s", s->name); + } + mutex_unlock(&memcg->slab_caches_mutex); + seq_printf(m, "\n"); +#endif +} + +/* + * After a memcg is destroyed, it may still be kept around in memory. + * Currently, the two main reasons for it are swap entries, and kernel memory. + * Because they will be freed assynchronously, they will pin the memcg structure + * and its resources until the last reference goes away. + * + * This root-only file will show information about which users + */ +static int mem_cgroup_dangling_read(struct cgroup *cont, struct cftype *cft, + struct seq_file *m) +{ + struct mem_cgroup *memcg; + + mutex_lock(&dangling_memcgs_mutex); + + list_for_each_entry(memcg, &dangling_memcgs, dead) { + if (memcg->memcg_name) + seq_printf(m, "%s:\n", memcg->memcg_name); + else + seq_printf(m, "%p (name lost):\n", memcg); + + mem_cgroup_dangling_swap(memcg, m); + mem_cgroup_dangling_tcp(memcg, m); + mem_cgroup_dangling_kmem(memcg, m); + } + + mutex_unlock(&dangling_memcgs_mutex); + return 0; +} +#endif + static int memcg_update_kmem_limit(struct cgroup *cont, u64 val) { int ret = -EINVAL; @@ -5871,6 +6038,14 @@ static struct cftype mem_cgroup_files[] = { }, #endif #endif + +#ifdef CONFIG_MEMCG_DEBUG_ASYNC_DESTROY + { + .name = "dangling_memcgs", + .read_seq_string = mem_cgroup_dangling_read, + .flags = CFTYPE_ONLY_ON_ROOT, + }, +#endif { }, /* terminate */ }; @@ -6020,6 +6195,8 @@ static void free_work(struct work_struct *work) struct mem_cgroup *memcg; memcg = container_of(work, struct mem_cgroup, work_freeing); + + memcg_dangling_free(memcg); __mem_cgroup_free(memcg); } @@ -6194,6 +6371,7 @@ static void mem_cgroup_css_free(struct cgroup *cont) kmem_cgroup_destroy(memcg); + memcg_dangling_add(memcg); mem_cgroup_put(memcg); } |