memcg: use for_each_mem_cgroup
In memory cgroup management, we sometimes have to walk through subhierarchy of cgroup to gather informaiton, or lock something, etc. Now, to do that, mem_cgroup_walk_tree() function is provided. It calls given callback function per cgroup found. But the bad thing is that it has to pass a fixed style function and argument, "void*" and it adds much type casting to memcontrol.c. To make the code clean, this patch replaces walk_tree() with for_each_mem_cgroup_tree(iter, root) An iterator style call. The good point is that iterator call doesn't have to assume what kind of function is called under it. A bad point is that it may cause reference-count leak if a caller use "break" from the loop by mistake. I think the benefit is larger. The modified code seems straigtforward and easy to read because we don't have misterious callbacks and pointer cast. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
KAMEZAWA Hiroyuki
Linus Torvalds
parent
32047e2a85
commit
7d74b06f24
188
mm/memcontrol.c
188
mm/memcontrol.c
@ -660,41 +660,58 @@ static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
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return mem;
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}
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/*
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* Call callback function against all cgroup under hierarchy tree.
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*/
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static int mem_cgroup_walk_tree(struct mem_cgroup *root, void *data,
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int (*func)(struct mem_cgroup *, void *))
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/* The caller has to guarantee "mem" exists before calling this */
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static struct mem_cgroup *mem_cgroup_start_loop(struct mem_cgroup *mem)
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{
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int found, ret, nextid;
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struct cgroup_subsys_state *css;
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struct mem_cgroup *mem;
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if (!root->use_hierarchy)
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return (*func)(root, data);
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nextid = 1;
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do {
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ret = 0;
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mem = NULL;
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rcu_read_lock();
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css = css_get_next(&mem_cgroup_subsys, nextid, &root->css,
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&found);
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if (css && css_tryget(css))
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mem = container_of(css, struct mem_cgroup, css);
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rcu_read_unlock();
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if (mem) {
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ret = (*func)(mem, data);
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css_put(&mem->css);
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}
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nextid = found + 1;
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} while (!ret && css);
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return ret;
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if (mem && css_tryget(&mem->css))
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return mem;
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return NULL;
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}
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static struct mem_cgroup *mem_cgroup_get_next(struct mem_cgroup *iter,
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struct mem_cgroup *root,
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bool cond)
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{
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int nextid = css_id(&iter->css) + 1;
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int found;
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int hierarchy_used;
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struct cgroup_subsys_state *css;
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hierarchy_used = iter->use_hierarchy;
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css_put(&iter->css);
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if (!cond || !hierarchy_used)
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return NULL;
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do {
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iter = NULL;
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rcu_read_lock();
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css = css_get_next(&mem_cgroup_subsys, nextid,
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&root->css, &found);
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if (css && css_tryget(css))
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iter = container_of(css, struct mem_cgroup, css);
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rcu_read_unlock();
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/* If css is NULL, no more cgroups will be found */
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nextid = found + 1;
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} while (css && !iter);
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return iter;
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}
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/*
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* for_eacn_mem_cgroup_tree() for visiting all cgroup under tree. Please
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* be careful that "break" loop is not allowed. We have reference count.
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* Instead of that modify "cond" to be false and "continue" to exit the loop.
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*/
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#define for_each_mem_cgroup_tree_cond(iter, root, cond) \
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for (iter = mem_cgroup_start_loop(root);\
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iter != NULL;\
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iter = mem_cgroup_get_next(iter, root, cond))
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#define for_each_mem_cgroup_tree(iter, root) \
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for_each_mem_cgroup_tree_cond(iter, root, true)
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static inline bool mem_cgroup_is_root(struct mem_cgroup *mem)
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{
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return (mem == root_mem_cgroup);
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@ -1132,13 +1149,6 @@ static bool mem_cgroup_wait_acct_move(struct mem_cgroup *mem)
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return false;
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}
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static int mem_cgroup_count_children_cb(struct mem_cgroup *mem, void *data)
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{
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int *val = data;
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(*val)++;
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return 0;
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}
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/**
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* mem_cgroup_print_oom_info: Called from OOM with tasklist_lock held in read mode.
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* @memcg: The memory cgroup that went over limit
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@ -1213,7 +1223,10 @@ void mem_cgroup_print_oom_info(struct mem_cgroup *memcg, struct task_struct *p)
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static int mem_cgroup_count_children(struct mem_cgroup *mem)
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{
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int num = 0;
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mem_cgroup_walk_tree(mem, &num, mem_cgroup_count_children_cb);
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struct mem_cgroup *iter;
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for_each_mem_cgroup_tree(iter, mem)
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num++;
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return num;
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}
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@ -1362,49 +1375,39 @@ static int mem_cgroup_hierarchical_reclaim(struct mem_cgroup *root_mem,
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return total;
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}
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static int mem_cgroup_oom_lock_cb(struct mem_cgroup *mem, void *data)
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{
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int *val = (int *)data;
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int x;
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/*
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* Logically, we can stop scanning immediately when we find
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* a memcg is already locked. But condidering unlock ops and
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* creation/removal of memcg, scan-all is simple operation.
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*/
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x = atomic_inc_return(&mem->oom_lock);
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*val = max(x, *val);
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return 0;
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}
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/*
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* Check OOM-Killer is already running under our hierarchy.
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* If someone is running, return false.
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*/
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static bool mem_cgroup_oom_lock(struct mem_cgroup *mem)
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{
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int lock_count = 0;
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int x, lock_count = 0;
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struct mem_cgroup *iter;
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mem_cgroup_walk_tree(mem, &lock_count, mem_cgroup_oom_lock_cb);
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for_each_mem_cgroup_tree(iter, mem) {
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x = atomic_inc_return(&iter->oom_lock);
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lock_count = max(x, lock_count);
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}
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if (lock_count == 1)
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return true;
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return false;
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}
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static int mem_cgroup_oom_unlock_cb(struct mem_cgroup *mem, void *data)
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static int mem_cgroup_oom_unlock(struct mem_cgroup *mem)
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{
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struct mem_cgroup *iter;
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/*
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* When a new child is created while the hierarchy is under oom,
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* mem_cgroup_oom_lock() may not be called. We have to use
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* atomic_add_unless() here.
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*/
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atomic_add_unless(&mem->oom_lock, -1, 0);
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for_each_mem_cgroup_tree(iter, mem)
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atomic_add_unless(&iter->oom_lock, -1, 0);
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return 0;
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}
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static void mem_cgroup_oom_unlock(struct mem_cgroup *mem)
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{
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mem_cgroup_walk_tree(mem, NULL, mem_cgroup_oom_unlock_cb);
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}
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static DEFINE_MUTEX(memcg_oom_mutex);
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static DECLARE_WAIT_QUEUE_HEAD(memcg_oom_waitq);
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@ -3207,33 +3210,25 @@ static int mem_cgroup_hierarchy_write(struct cgroup *cont, struct cftype *cft,
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return retval;
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}
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struct mem_cgroup_idx_data {
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s64 val;
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enum mem_cgroup_stat_index idx;
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};
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static int
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mem_cgroup_get_idx_stat(struct mem_cgroup *mem, void *data)
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static u64 mem_cgroup_get_recursive_idx_stat(struct mem_cgroup *mem,
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enum mem_cgroup_stat_index idx)
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{
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struct mem_cgroup_idx_data *d = data;
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d->val += mem_cgroup_read_stat(mem, d->idx);
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return 0;
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}
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struct mem_cgroup *iter;
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s64 val = 0;
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static void
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mem_cgroup_get_recursive_idx_stat(struct mem_cgroup *mem,
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enum mem_cgroup_stat_index idx, s64 *val)
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{
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struct mem_cgroup_idx_data d;
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d.idx = idx;
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d.val = 0;
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mem_cgroup_walk_tree(mem, &d, mem_cgroup_get_idx_stat);
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*val = d.val;
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/* each per cpu's value can be minus.Then, use s64 */
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for_each_mem_cgroup_tree(iter, mem)
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val += mem_cgroup_read_stat(iter, idx);
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if (val < 0) /* race ? */
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val = 0;
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return val;
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}
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static inline u64 mem_cgroup_usage(struct mem_cgroup *mem, bool swap)
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{
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u64 idx_val, val;
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u64 val;
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if (!mem_cgroup_is_root(mem)) {
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if (!swap)
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@ -3242,16 +3237,12 @@ static inline u64 mem_cgroup_usage(struct mem_cgroup *mem, bool swap)
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return res_counter_read_u64(&mem->memsw, RES_USAGE);
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}
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mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_CACHE, &idx_val);
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val = idx_val;
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mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_RSS, &idx_val);
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val += idx_val;
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val = mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_CACHE);
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val += mem_cgroup_get_recursive_idx_stat(mem, MEM_CGROUP_STAT_RSS);
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if (swap) {
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mem_cgroup_get_recursive_idx_stat(mem,
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MEM_CGROUP_STAT_SWAPOUT, &idx_val);
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val += idx_val;
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}
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if (swap)
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val += mem_cgroup_get_recursive_idx_stat(mem,
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MEM_CGROUP_STAT_SWAPOUT);
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return val << PAGE_SHIFT;
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}
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@ -3459,9 +3450,9 @@ struct {
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};
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static int mem_cgroup_get_local_stat(struct mem_cgroup *mem, void *data)
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static void
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mem_cgroup_get_local_stat(struct mem_cgroup *mem, struct mcs_total_stat *s)
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{
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struct mcs_total_stat *s = data;
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s64 val;
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/* per cpu stat */
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@ -3491,13 +3482,15 @@ static int mem_cgroup_get_local_stat(struct mem_cgroup *mem, void *data)
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s->stat[MCS_ACTIVE_FILE] += val * PAGE_SIZE;
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val = mem_cgroup_get_local_zonestat(mem, LRU_UNEVICTABLE);
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s->stat[MCS_UNEVICTABLE] += val * PAGE_SIZE;
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return 0;
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}
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static void
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mem_cgroup_get_total_stat(struct mem_cgroup *mem, struct mcs_total_stat *s)
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{
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mem_cgroup_walk_tree(mem, s, mem_cgroup_get_local_stat);
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struct mem_cgroup *iter;
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for_each_mem_cgroup_tree(iter, mem)
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mem_cgroup_get_local_stat(iter, s);
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}
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static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
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@ -3674,7 +3667,7 @@ static int compare_thresholds(const void *a, const void *b)
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return _a->threshold - _b->threshold;
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}
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static int mem_cgroup_oom_notify_cb(struct mem_cgroup *mem, void *data)
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static int mem_cgroup_oom_notify_cb(struct mem_cgroup *mem)
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{
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struct mem_cgroup_eventfd_list *ev;
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@ -3685,7 +3678,10 @@ static int mem_cgroup_oom_notify_cb(struct mem_cgroup *mem, void *data)
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static void mem_cgroup_oom_notify(struct mem_cgroup *mem)
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{
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mem_cgroup_walk_tree(mem, NULL, mem_cgroup_oom_notify_cb);
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struct mem_cgroup *iter;
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for_each_mem_cgroup_tree(iter, mem)
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mem_cgroup_oom_notify_cb(iter);
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}
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static int mem_cgroup_usage_register_event(struct cgroup *cgrp,
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