Re: [PATCH v6 00/33] Eliminate Dying Memory Cgroup
From: Andrew Morton
Date: Thu Mar 05 2026 - 19:52:05 EST
On Thu, 5 Mar 2026 19:52:18 +0800 Qi Zheng <qi.zheng@xxxxxxxxx> wrote:
> - refactor mod_memcg_state() and mod_memcg_lruvec_state()
> (suggested by Yosry Ahmed)
> - use non-atomic method to reparent non-hierarchical stats
> (suggested by Yosry Ahmed)
> - remove the redundant declaration in [PATCH v5 29/32]
> (pointed by Shakeel Butt)
> - collect Acked-bys
Updated, thanks.
Appended is how this update altered mm.git.
Hopefully we'll be able to move this into mm-unstable (and hance
linux-next) soon,
--- a/kernel/cgroup/cgroup.c~b
+++ a/kernel/cgroup/cgroup.c
@@ -6043,8 +6043,9 @@ out_unlock:
*/
static void css_killed_work_fn(struct work_struct *work)
{
- struct cgroup_subsys_state *css = container_of(to_rcu_work(work),
- struct cgroup_subsys_state, destroy_rwork);
+ struct cgroup_subsys_state *css;
+
+ css = container_of(to_rcu_work(work), struct cgroup_subsys_state, destroy_rwork);
cgroup_lock();
--- a/mm/memcontrol.c~b
+++ a/mm/memcontrol.c
@@ -526,25 +526,25 @@ unsigned long lruvec_page_state_local(st
}
#ifdef CONFIG_MEMCG_V1
-static void __mod_memcg_lruvec_state(struct lruvec *lruvec,
+static void __mod_memcg_lruvec_state(struct mem_cgroup_per_node *pn,
enum node_stat_item idx, int val);
void reparent_memcg_lruvec_state_local(struct mem_cgroup *memcg,
struct mem_cgroup *parent, int idx)
{
- int i = memcg_stats_index(idx);
int nid;
- if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx))
- return;
-
for_each_node(nid) {
struct lruvec *child_lruvec = mem_cgroup_lruvec(memcg, NODE_DATA(nid));
struct lruvec *parent_lruvec = mem_cgroup_lruvec(parent, NODE_DATA(nid));
unsigned long value = lruvec_page_state_local(child_lruvec, idx);
+ struct mem_cgroup_per_node *child_pn, *parent_pn;
- __mod_memcg_lruvec_state(child_lruvec, idx, -value);
- __mod_memcg_lruvec_state(parent_lruvec, idx, value);
+ child_pn = container_of(child_lruvec, struct mem_cgroup_per_node, lruvec);
+ parent_pn = container_of(parent_lruvec, struct mem_cgroup_per_node, lruvec);
+
+ __mod_memcg_lruvec_state(child_pn, idx, -value);
+ __mod_memcg_lruvec_state(parent_pn, idx, value);
}
}
#endif
@@ -830,39 +830,43 @@ static inline void get_non_dying_memcg_e
}
#endif
-/**
- * mod_memcg_state - update cgroup memory statistics
- * @memcg: the memory cgroup
- * @idx: the stat item - can be enum memcg_stat_item or enum node_stat_item
- * @val: delta to add to the counter, can be negative
- */
-void mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx,
- int val)
+static void __mod_memcg_state(struct mem_cgroup *memcg,
+ enum memcg_stat_item idx, int val)
{
int i = memcg_stats_index(idx);
int cpu;
- if (mem_cgroup_disabled())
- return;
-
if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx))
return;
cpu = get_cpu();
- memcg = get_non_dying_memcg_start(memcg);
-
this_cpu_add(memcg->vmstats_percpu->state[i], val);
val = memcg_state_val_in_pages(idx, val);
memcg_rstat_updated(memcg, val, cpu);
- get_non_dying_memcg_end();
-
trace_mod_memcg_state(memcg, idx, val);
put_cpu();
}
+/**
+ * mod_memcg_state - update cgroup memory statistics
+ * @memcg: the memory cgroup
+ * @idx: the stat item - can be enum memcg_stat_item or enum node_stat_item
+ * @val: delta to add to the counter, can be negative
+ */
+void mod_memcg_state(struct mem_cgroup *memcg, enum memcg_stat_item idx,
+ int val)
+{
+ if (mem_cgroup_disabled())
+ return;
+
+ memcg = get_non_dying_memcg_start(memcg);
+ __mod_memcg_state(memcg, idx, val);
+ get_non_dying_memcg_end();
+}
+
#ifdef CONFIG_MEMCG_V1
/* idx can be of type enum memcg_stat_item or node_stat_item. */
unsigned long memcg_page_state_local(struct mem_cgroup *memcg, int idx)
@@ -881,35 +885,25 @@ unsigned long memcg_page_state_local(str
return x;
}
-static void __mod_memcg_state(struct mem_cgroup *memcg,
- enum memcg_stat_item idx, int val)
+void reparent_memcg_state_local(struct mem_cgroup *memcg,
+ struct mem_cgroup *parent, int idx)
{
- int i = memcg_stats_index(idx);
- int cpu;
-
- if (mem_cgroup_disabled())
- return;
-
- cpu = get_cpu();
-
- this_cpu_add(memcg->vmstats_percpu->state[i], val);
- val = memcg_state_val_in_pages(idx, val);
- memcg_rstat_updated(memcg, val, cpu);
- trace_mod_memcg_state(memcg, idx, val);
+ unsigned long value = memcg_page_state_local(memcg, idx);
- put_cpu();
+ __mod_memcg_state(memcg, idx, -value);
+ __mod_memcg_state(parent, idx, value);
}
+#endif
-static void __mod_memcg_lruvec_state(struct lruvec *lruvec,
+static void __mod_memcg_lruvec_state(struct mem_cgroup_per_node *pn,
enum node_stat_item idx, int val)
{
- struct mem_cgroup_per_node *pn;
- struct mem_cgroup *memcg;
+ struct mem_cgroup *memcg = pn->memcg;
int i = memcg_stats_index(idx);
int cpu;
- pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
- memcg = pn->memcg;
+ if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx))
+ return;
cpu = get_cpu();
@@ -926,20 +920,6 @@ static void __mod_memcg_lruvec_state(str
put_cpu();
}
-void reparent_memcg_state_local(struct mem_cgroup *memcg,
- struct mem_cgroup *parent, int idx)
-{
- int i = memcg_stats_index(idx);
- unsigned long value = memcg_page_state_local(memcg, idx);
-
- if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx))
- return;
-
- __mod_memcg_state(memcg, idx, -value);
- __mod_memcg_state(parent, idx, value);
-}
-#endif
-
static void mod_memcg_lruvec_state(struct lruvec *lruvec,
enum node_stat_item idx,
int val)
@@ -947,32 +927,14 @@ static void mod_memcg_lruvec_state(struc
struct pglist_data *pgdat = lruvec_pgdat(lruvec);
struct mem_cgroup_per_node *pn;
struct mem_cgroup *memcg;
- int i = memcg_stats_index(idx);
- int cpu;
-
- if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx))
- return;
pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
- memcg = pn->memcg;
-
- cpu = get_cpu();
-
- memcg = get_non_dying_memcg_start(memcg);
+ memcg = get_non_dying_memcg_start(pn->memcg);
pn = memcg->nodeinfo[pgdat->node_id];
- /* Update memcg */
- this_cpu_add(memcg->vmstats_percpu->state[i], val);
- /* Update lruvec */
- this_cpu_add(pn->lruvec_stats_percpu->state[i], val);
- val = memcg_state_val_in_pages(idx, val);
- memcg_rstat_updated(memcg, val, cpu);
+ __mod_memcg_lruvec_state(pn, idx, val);
get_non_dying_memcg_end();
-
- trace_mod_memcg_lruvec_state(memcg, idx, val);
-
- put_cpu();
}
/**
_