return memcg;
}
-/* The caller has to guarantee "mem" exists before calling this */
-static struct mem_cgroup *mem_cgroup_start_loop(struct mem_cgroup *memcg)
+static struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
+ struct mem_cgroup *prev,
+ bool reclaim)
{
- struct cgroup_subsys_state *css;
- int found;
+ struct mem_cgroup *memcg = NULL;
+ int id = 0;
- if (!memcg) /* ROOT cgroup has the smallest ID */
- return root_mem_cgroup; /*css_put/get against root is ignored*/
- if (!memcg->use_hierarchy) {
- if (css_tryget(&memcg->css))
- return memcg;
- return NULL;
- }
- rcu_read_lock();
- /*
- * searching a memory cgroup which has the smallest ID under given
- * ROOT cgroup. (ID >= 1)
- */
- css = css_get_next(&mem_cgroup_subsys, 1, &memcg->css, &found);
- if (css && css_tryget(css))
- memcg = container_of(css, struct mem_cgroup, css);
- else
- memcg = NULL;
- rcu_read_unlock();
- return memcg;
-}
+ if (!root)
+ root = root_mem_cgroup;
-static struct mem_cgroup *mem_cgroup_get_next(struct mem_cgroup *iter,
- struct mem_cgroup *root,
- bool cond)
-{
- int nextid = css_id(&iter->css) + 1;
- int found;
- int hierarchy_used;
- struct cgroup_subsys_state *css;
+ if (prev && !reclaim)
+ id = css_id(&prev->css);
- hierarchy_used = iter->use_hierarchy;
+ if (prev && prev != root)
+ css_put(&prev->css);
- css_put(&iter->css);
- /* If no ROOT, walk all, ignore hierarchy */
- if (!cond || (root && !hierarchy_used))
- return NULL;
+ if (!root->use_hierarchy && root != root_mem_cgroup) {
+ if (prev)
+ return NULL;
+ return root;
+ }
- if (!root)
- root = root_mem_cgroup;
+ while (!memcg) {
+ struct cgroup_subsys_state *css;
- do {
- iter = NULL;
- rcu_read_lock();
+ if (reclaim)
+ id = root->last_scanned_child;
- css = css_get_next(&mem_cgroup_subsys, nextid,
- &root->css, &found);
- if (css && css_tryget(css))
- iter = container_of(css, struct mem_cgroup, css);
+ rcu_read_lock();
+ css = css_get_next(&mem_cgroup_subsys, id + 1, &root->css, &id);
+ if (css) {
+ if (css == &root->css || css_tryget(css))
+ memcg = container_of(css,
+ struct mem_cgroup, css);
+ } else
+ id = 0;
rcu_read_unlock();
- /* If css is NULL, no more cgroups will be found */
- nextid = found + 1;
- } while (css && !iter);
- return iter;
+ if (reclaim)
+ root->last_scanned_child = id;
+
+ if (prev && !css)
+ return NULL;
+ }
+ return memcg;
}
-/*
- * for_eacn_mem_cgroup_tree() for visiting all cgroup under tree. Please
- * be careful that "break" loop is not allowed. We have reference count.
- * Instead of that modify "cond" to be false and "continue" to exit the loop.
- */
-#define for_each_mem_cgroup_tree_cond(iter, root, cond) \
- for (iter = mem_cgroup_start_loop(root);\
- iter != NULL;\
- iter = mem_cgroup_get_next(iter, root, cond))
-#define for_each_mem_cgroup_tree(iter, root) \
- for_each_mem_cgroup_tree_cond(iter, root, true)
+static void mem_cgroup_iter_break(struct mem_cgroup *root,
+ struct mem_cgroup *prev)
+{
+ if (!root)
+ root = root_mem_cgroup;
+ if (prev && prev != root)
+ css_put(&prev->css);
+}
-#define for_each_mem_cgroup_all(iter) \
- for_each_mem_cgroup_tree_cond(iter, NULL, true)
+/*
+ * Iteration constructs for visiting all cgroups (under a tree). If
+ * loops are exited prematurely (break), mem_cgroup_iter_break() must
+ * be used for reference counting.
+ */
+#define for_each_mem_cgroup_tree(iter, root) \
+ for (iter = mem_cgroup_iter(root, NULL, false); \
+ iter != NULL; \
+ iter = mem_cgroup_iter(root, iter, false))
+#define for_each_mem_cgroup(iter) \
+ for (iter = mem_cgroup_iter(NULL, NULL, false); \
+ iter != NULL; \
+ iter = mem_cgroup_iter(NULL, iter, false))
static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
{
return min(limit, memsw);
}
-/*
- * Visit the first child (need not be the first child as per the ordering
- * of the cgroup list, since we track last_scanned_child) of @mem and use
- * that to reclaim free pages from.
- */
-static struct mem_cgroup *
-mem_cgroup_select_victim(struct mem_cgroup *root_memcg)
-{
- struct mem_cgroup *ret = NULL;
- struct cgroup_subsys_state *css;
- int nextid, found;
-
- if (!root_memcg->use_hierarchy) {
- css_get(&root_memcg->css);
- ret = root_memcg;
- }
-
- while (!ret) {
- rcu_read_lock();
- nextid = root_memcg->last_scanned_child + 1;
- css = css_get_next(&mem_cgroup_subsys, nextid, &root_memcg->css,
- &found);
- if (css && css_tryget(css))
- ret = container_of(css, struct mem_cgroup, css);
-
- rcu_read_unlock();
- /* Updates scanning parameter */
- if (!css) {
- /* this means start scan from ID:1 */
- root_memcg->last_scanned_child = 0;
- } else
- root_memcg->last_scanned_child = found;
- }
-
- return ret;
-}
-
/**
* test_mem_cgroup_node_reclaimable
* @mem: the target memcg
unsigned long reclaim_options,
unsigned long *total_scanned)
{
- struct mem_cgroup *victim;
+ struct mem_cgroup *victim = NULL;
int ret, total = 0;
int loop = 0;
bool noswap = reclaim_options & MEM_CGROUP_RECLAIM_NOSWAP;
noswap = true;
while (1) {
- victim = mem_cgroup_select_victim(root_memcg);
- if (victim == root_memcg) {
+ victim = mem_cgroup_iter(root_memcg, victim, true);
+ if (!victim) {
loop++;
/*
* We are not draining per cpu cached charges during
* anything, it might because there are
* no reclaimable pages under this hierarchy
*/
- if (!check_soft || !total) {
- css_put(&victim->css);
+ if (!check_soft || !total)
break;
- }
/*
* We want to do more targeted reclaim.
* excess >> 2 is not to excessive so as to
* coming back to reclaim from this cgroup
*/
if (total >= (excess >> 2) ||
- (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS)) {
- css_put(&victim->css);
+ (loop > MEM_CGROUP_MAX_RECLAIM_LOOPS))
break;
- }
}
+ continue;
}
if (!mem_cgroup_reclaimable(victim, noswap)) {
/* this cgroup's local usage == 0 */
- css_put(&victim->css);
continue;
}
/* we use swappiness of local cgroup */
} else
ret = try_to_free_mem_cgroup_pages(victim, gfp_mask,
noswap);
- css_put(&victim->css);
+ total += ret;
/*
* At shrinking usage, we can't check we should stop here or
* reclaim more. It's depends on callers. last_scanned_child
* will work enough for keeping fairness under tree.
*/
if (shrink)
- return ret;
- total += ret;
+ break;
if (check_soft) {
if (!res_counter_soft_limit_excess(&root_memcg->res))
- return total;
+ break;
} else if (mem_cgroup_margin(root_memcg))
- return total;
+ break;
}
+ mem_cgroup_iter_break(root_memcg, victim);
return total;
}
static bool mem_cgroup_oom_lock(struct mem_cgroup *memcg)
{
struct mem_cgroup *iter, *failed = NULL;
- bool cond = true;
- for_each_mem_cgroup_tree_cond(iter, memcg, cond) {
+ for_each_mem_cgroup_tree(iter, memcg) {
if (iter->oom_lock) {
/*
* this subtree of our hierarchy is already locked
* so we cannot give a lock.
*/
failed = iter;
- cond = false;
+ mem_cgroup_iter_break(memcg, iter);
+ break;
} else
iter->oom_lock = true;
}
* OK, we failed to lock the whole subtree so we have to clean up
* what we set up to the failing subtree
*/
- cond = true;
- for_each_mem_cgroup_tree_cond(iter, memcg, cond) {
+ for_each_mem_cgroup_tree(iter, memcg) {
if (iter == failed) {
- cond = false;
- continue;
+ mem_cgroup_iter_break(memcg, iter);
+ break;
}
iter->oom_lock = false;
}
struct mem_cgroup *iter;
if ((action == CPU_ONLINE)) {
- for_each_mem_cgroup_all(iter)
+ for_each_mem_cgroup(iter)
synchronize_mem_cgroup_on_move(iter, cpu);
return NOTIFY_OK;
}
if ((action != CPU_DEAD) || action != CPU_DEAD_FROZEN)
return NOTIFY_OK;
- for_each_mem_cgroup_all(iter)
+ for_each_mem_cgroup(iter)
mem_cgroup_drain_pcp_counter(iter, cpu);
stock = &per_cpu(memcg_stock, cpu);
projects / mirror_ubuntu-focal-kernel.git / commitdiff