diff options
| -rw-r--r-- | mm/memcontrol.c | 151 |
1 files changed, 66 insertions, 85 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a4172a861b30..c6ece0a57595 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -158,6 +158,18 @@ struct mem_cgroup_threshold_ary { /* Array of thresholds */ struct mem_cgroup_threshold entries[0]; }; + +struct mem_cgroup_thresholds { + /* Primary thresholds array */ + struct mem_cgroup_threshold_ary *primary; + /* + * Spare threshold array. + * This is needed to make mem_cgroup_unregister_event() "never fail". + * It must be able to store at least primary->size - 1 entries. + */ + struct mem_cgroup_threshold_ary *spare; +}; + /* for OOM */ struct mem_cgroup_eventfd_list { struct list_head list; @@ -224,20 +236,10 @@ struct mem_cgroup { struct mutex thresholds_lock; /* thresholds for memory usage. RCU-protected */ - struct mem_cgroup_threshold_ary *thresholds; - - /* - * Preallocated buffer to be used in mem_cgroup_unregister_event() - * to make it "never fail". - * It must be able to store at least thresholds->size - 1 entries. - */ - struct mem_cgroup_threshold_ary *__thresholds; + struct mem_cgroup_thresholds thresholds; /* thresholds for mem+swap usage. RCU-protected */ - struct mem_cgroup_threshold_ary *memsw_thresholds; - - /* the same as __thresholds, but for memsw_thresholds */ - struct mem_cgroup_threshold_ary *__memsw_thresholds; + struct mem_cgroup_thresholds memsw_thresholds; /* For oom notifier event fd */ struct list_head oom_notify; @@ -3467,9 +3469,9 @@ static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap) rcu_read_lock(); if (!swap) - t = rcu_dereference(memcg->thresholds); + t = rcu_dereference(memcg->thresholds.primary); else - t = rcu_dereference(memcg->memsw_thresholds); + t = rcu_dereference(memcg->memsw_thresholds.primary); if (!t) goto unlock; @@ -3543,91 +3545,78 @@ static int mem_cgroup_usage_register_event(struct cgroup *cgrp, struct cftype *cft, struct eventfd_ctx *eventfd, const char *args) { struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp); - struct mem_cgroup_threshold_ary *thresholds, *thresholds_new; + struct mem_cgroup_thresholds *thresholds; + struct mem_cgroup_threshold_ary *new; int type = MEMFILE_TYPE(cft->private); u64 threshold, usage; - int size; - int i, ret; + int i, size, ret; ret = res_counter_memparse_write_strategy(args, &threshold); if (ret) return ret; mutex_lock(&memcg->thresholds_lock); + if (type == _MEM) - thresholds = memcg->thresholds; + thresholds = &memcg->thresholds; else if (type == _MEMSWAP) - thresholds = memcg->memsw_thresholds; + thresholds = &memcg->memsw_thresholds; else BUG(); usage = mem_cgroup_usage(memcg, type == _MEMSWAP); /* Check if a threshold crossed before adding a new one */ - if (thresholds) + if (thresholds->primary) __mem_cgroup_threshold(memcg, type == _MEMSWAP); - if (thresholds) - size = thresholds->size + 1; - else - size = 1; + size = thresholds->primary ? thresholds->primary->size + 1 : 1; /* Allocate memory for new array of thresholds */ - thresholds_new = kmalloc(sizeof(*thresholds_new) + - size * sizeof(struct mem_cgroup_threshold), + new = kmalloc(sizeof(*new) + size * sizeof(struct mem_cgroup_threshold), GFP_KERNEL); - if (!thresholds_new) { + if (!new) { ret = -ENOMEM; goto unlock; } - thresholds_new->size = size; + new->size = size; /* Copy thresholds (if any) to new array */ - if (thresholds) - memcpy(thresholds_new->entries, thresholds->entries, - thresholds->size * + if (thresholds->primary) { + memcpy(new->entries, thresholds->primary->entries, (size - 1) * sizeof(struct mem_cgroup_threshold)); + } + /* Add new threshold */ - thresholds_new->entries[size - 1].eventfd = eventfd; - thresholds_new->entries[size - 1].threshold = threshold; + new->entries[size - 1].eventfd = eventfd; + new->entries[size - 1].threshold = threshold; /* Sort thresholds. Registering of new threshold isn't time-critical */ - sort(thresholds_new->entries, size, - sizeof(struct mem_cgroup_threshold), + sort(new->entries, size, sizeof(struct mem_cgroup_threshold), compare_thresholds, NULL); /* Find current threshold */ - thresholds_new->current_threshold = -1; + new->current_threshold = -1; for (i = 0; i < size; i++) { - if (thresholds_new->entries[i].threshold < usage) { + if (new->entries[i].threshold < usage) { /* - * thresholds_new->current_threshold will not be used - * until rcu_assign_pointer(), so it's safe to increment + * new->current_threshold will not be used until + * rcu_assign_pointer(), so it's safe to increment * it here. */ - ++thresholds_new->current_threshold; + ++new->current_threshold; } } - if (type == _MEM) - rcu_assign_pointer(memcg->thresholds, thresholds_new); - else - rcu_assign_pointer(memcg->memsw_thresholds, thresholds_new); + /* Free old spare buffer and save old primary buffer as spare */ + kfree(thresholds->spare); + thresholds->spare = thresholds->primary; + + rcu_assign_pointer(thresholds->primary, new); /* To be sure that nobody uses thresholds */ synchronize_rcu(); - /* - * Free old preallocated buffer and use thresholds as new - * preallocated buffer. - */ - if (type == _MEM) { - kfree(memcg->__thresholds); - memcg->__thresholds = thresholds; - } else { - kfree(memcg->__memsw_thresholds); - memcg->__memsw_thresholds = thresholds; - } unlock: mutex_unlock(&memcg->thresholds_lock); @@ -3638,17 +3627,17 @@ static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp, struct cftype *cft, struct eventfd_ctx *eventfd) { struct mem_cgroup *memcg = mem_cgroup_from_cont(cgrp); - struct mem_cgroup_threshold_ary *thresholds, *thresholds_new; + struct mem_cgroup_thresholds *thresholds; + struct mem_cgroup_threshold_ary *new; int type = MEMFILE_TYPE(cft->private); u64 usage; - int size = 0; - int i, j; + int i, j, size; mutex_lock(&memcg->thresholds_lock); if (type == _MEM) - thresholds = memcg->thresholds; + thresholds = &memcg->thresholds; else if (type == _MEMSWAP) - thresholds = memcg->memsw_thresholds; + thresholds = &memcg->memsw_thresholds; else BUG(); @@ -3664,53 +3653,45 @@ static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp, __mem_cgroup_threshold(memcg, type == _MEMSWAP); /* Calculate new number of threshold */ - for (i = 0; i < thresholds->size; i++) { - if (thresholds->entries[i].eventfd != eventfd) + size = 0; + for (i = 0; i < thresholds->primary->size; i++) { + if (thresholds->primary->entries[i].eventfd != eventfd) size++; } - /* Use preallocated buffer for new array of thresholds */ - if (type == _MEM) - thresholds_new = memcg->__thresholds; - else - thresholds_new = memcg->__memsw_thresholds; + new = thresholds->spare; /* Set thresholds array to NULL if we don't have thresholds */ if (!size) { - kfree(thresholds_new); - thresholds_new = NULL; + kfree(new); + new = NULL; goto swap_buffers; } - thresholds_new->size = size; + new->size = size; /* Copy thresholds and find current threshold */ - thresholds_new->current_threshold = -1; - for (i = 0, j = 0; i < thresholds->size; i++) { - if (thresholds->entries[i].eventfd == eventfd) + new->current_threshold = -1; + for (i = 0, j = 0; i < thresholds->primary->size; i++) { + if (thresholds->primary->entries[i].eventfd == eventfd) continue; - thresholds_new->entries[j] = thresholds->entries[i]; - if (thresholds_new->entries[j].threshold < usage) { + new->entries[j] = thresholds->primary->entries[i]; + if (new->entries[j].threshold < usage) { /* - * thresholds_new->current_threshold will not be used + * new->current_threshold will not be used * until rcu_assign_pointer(), so it's safe to increment * it here. */ - ++thresholds_new->current_threshold; + ++new->current_threshold; } j++; } swap_buffers: - /* Swap thresholds array and preallocated buffer */ - if (type == _MEM) { - memcg->__thresholds = thresholds; - rcu_assign_pointer(memcg->thresholds, thresholds_new); - } else { - memcg->__memsw_thresholds = thresholds; - rcu_assign_pointer(memcg->memsw_thresholds, thresholds_new); - } + /* Swap primary and spare array */ + thresholds->spare = thresholds->primary; + rcu_assign_pointer(thresholds->primary, new); /* To be sure that nobody uses thresholds */ synchronize_rcu(); |