Commit 30361e51 authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds

revert "memcg: track children in soft limit excess to improve soft limit"

Revert commit 7d910c05 ("memcg: track children in soft limit excess
to improve soft limit")

I merged this prematurely - Michal and Johannes still disagree about the
overall design direction and the future remains unclear.

Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 3120055e
......@@ -124,7 +124,6 @@ static const char * const mem_cgroup_lru_names[] = {
*/
enum mem_cgroup_events_target {
MEM_CGROUP_TARGET_THRESH,
MEM_CGROUP_TARGET_SOFTLIMIT,
MEM_CGROUP_TARGET_NUMAINFO,
MEM_CGROUP_NTARGETS,
};
......@@ -303,22 +302,6 @@ struct mem_cgroup {
atomic_t numainfo_events;
atomic_t numainfo_updating;
#endif
/*
* Protects soft_contributed transitions.
* See mem_cgroup_update_soft_limit
*/
spinlock_t soft_lock;
/*
* If true then this group has increased parents' children_in_excess
* when it got over the soft limit.
* When a group falls bellow the soft limit, parents' children_in_excess
* is decreased and soft_contributed changed to false.
*/
bool soft_contributed;
/* Number of children that are in soft limit excess */
atomic_t children_in_excess;
struct mem_cgroup_per_node *nodeinfo[0];
/* WARNING: nodeinfo must be the last member here */
......@@ -806,9 +789,6 @@ static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
case MEM_CGROUP_TARGET_THRESH:
next = val + THRESHOLDS_EVENTS_TARGET;
break;
case MEM_CGROUP_TARGET_SOFTLIMIT:
next = val + SOFTLIMIT_EVENTS_TARGET;
break;
case MEM_CGROUP_TARGET_NUMAINFO:
next = val + NUMAINFO_EVENTS_TARGET;
break;
......@@ -821,42 +801,6 @@ static bool mem_cgroup_event_ratelimit(struct mem_cgroup *memcg,
return false;
}
/*
* Called from rate-limited memcg_check_events when enough
* MEM_CGROUP_TARGET_SOFTLIMIT events are accumulated and it makes sure
* that all the parents up the hierarchy will be notified that this group
* is in excess or that it is not in excess anymore. mmecg->soft_contributed
* makes the transition a single action whenever the state flips from one to
* the other.
*/
static void mem_cgroup_update_soft_limit(struct mem_cgroup *memcg)
{
unsigned long long excess = res_counter_soft_limit_excess(&memcg->res);
struct mem_cgroup *parent = memcg;
int delta = 0;
spin_lock(&memcg->soft_lock);
if (excess) {
if (!memcg->soft_contributed) {
delta = 1;
memcg->soft_contributed = true;
}
} else {
if (memcg->soft_contributed) {
delta = -1;
memcg->soft_contributed = false;
}
}
/*
* Necessary to update all ancestors when hierarchy is used
* because their event counter is not touched.
*/
while (delta && (parent = parent_mem_cgroup(parent)))
atomic_add(delta, &parent->children_in_excess);
spin_unlock(&memcg->soft_lock);
}
/*
* Check events in order.
*
......@@ -867,11 +811,8 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
/* threshold event is triggered in finer grain than soft limit */
if (unlikely(mem_cgroup_event_ratelimit(memcg,
MEM_CGROUP_TARGET_THRESH))) {
bool do_softlimit;
bool do_numainfo __maybe_unused;
do_softlimit = mem_cgroup_event_ratelimit(memcg,
MEM_CGROUP_TARGET_SOFTLIMIT);
#if MAX_NUMNODES > 1
do_numainfo = mem_cgroup_event_ratelimit(memcg,
MEM_CGROUP_TARGET_NUMAINFO);
......@@ -879,8 +820,6 @@ static void memcg_check_events(struct mem_cgroup *memcg, struct page *page)
preempt_enable();
mem_cgroup_threshold(memcg);
if (unlikely(do_softlimit))
mem_cgroup_update_soft_limit(memcg);
#if MAX_NUMNODES > 1
if (unlikely(do_numainfo))
atomic_inc(&memcg->numainfo_events);
......@@ -1864,9 +1803,6 @@ int mem_cgroup_select_victim_node(struct mem_cgroup *memcg)
* hierarchy if
* a) it is over its soft limit
* b) any parent up the hierarchy is over its soft limit
*
* If the given group doesn't have any children over the limit then it
* doesn't make any sense to iterate its subtree.
*/
enum mem_cgroup_filter_t
mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg,
......@@ -1888,8 +1824,6 @@ mem_cgroup_soft_reclaim_eligible(struct mem_cgroup *memcg,
break;
}
if (!atomic_read(&memcg->children_in_excess))
return SKIP_TREE;
return SKIP;
}
......@@ -6021,7 +5955,6 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
mutex_init(&memcg->thresholds_lock);
spin_lock_init(&memcg->move_lock);
vmpressure_init(&memcg->vmpressure);
spin_lock_init(&memcg->soft_lock);
return &memcg->css;
......@@ -6099,10 +6032,6 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css)
mem_cgroup_invalidate_reclaim_iterators(memcg);
mem_cgroup_reparent_charges(memcg);
if (memcg->soft_contributed) {
while ((memcg = parent_mem_cgroup(memcg)))
atomic_dec(&memcg->children_in_excess);
}
mem_cgroup_destroy_all_caches(memcg);
vmpressure_cleanup(&memcg->vmpressure);
}
......
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