The patch titled
Subject: memcg: pr_warn_once for unexpected events and stats
has been added to the -mm mm-unstable branch. Its filename is
memcg-pr_warn_once-for-unexpected-events-and-stats.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/memcg-pr_warn_once-for-unexpected-events-and-stats.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Subject: memcg: pr_warn_once for unexpected events and stats
Date: Fri, 26 Apr 2024 17:37:31 -0700
To reduce memory usage by the memcg events and stats, the kernel uses
indirection table and only allocate stats and events which are being used
by the memcg code. To make this more robust, let's add warnings where
unexpected stats and events indexes are used.
Link: https://lkml.kernel.org/r/20240427003733.3898961-6-shakeel.butt@xxxxxxxxx
Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 43 ++++++++++++++++++++++++++++++++++---------
1 file changed, 34 insertions(+), 9 deletions(-)
--- a/mm/memcontrol.c~memcg-pr_warn_once-for-unexpected-events-and-stats
+++ a/mm/memcontrol.c
@@ -670,9 +670,11 @@ unsigned long lruvec_page_state(struct l
return node_page_state(lruvec_pgdat(lruvec), idx);
i = memcg_stats_index(idx);
- if (i >= 0) {
+ if (likely(i >= 0)) {
pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
x = READ_ONCE(pn->lruvec_stats->state[i]);
+ } else {
+ pr_warn_once("%s: stat item index: %d\n", __func__, idx);
}
#ifdef CONFIG_SMP
if (x < 0)
@@ -692,9 +694,11 @@ unsigned long lruvec_page_state_local(st
return node_page_state(lruvec_pgdat(lruvec), idx);
i = memcg_stats_index(idx);
- if (i >= 0) {
+ if (likely(i >= 0)) {
pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
x = READ_ONCE(pn->lruvec_stats->state_local[i]);
+ } else {
+ pr_warn_once("%s: stat item index: %d\n", __func__, idx);
}
#ifdef CONFIG_SMP
if (x < 0)
@@ -921,8 +925,10 @@ unsigned long memcg_page_state(struct me
long x;
int i = memcg_stats_index(idx);
- if (i < 0)
+ if (unlikely(i < 0)) {
+ pr_warn_once("%s: stat item index: %d\n", __func__, idx);
return 0;
+ }
x = READ_ONCE(memcg->vmstats->state[i]);
#ifdef CONFIG_SMP
@@ -958,8 +964,13 @@ void __mod_memcg_state(struct mem_cgroup
{
int i = memcg_stats_index(idx);
- if (mem_cgroup_disabled() || i < 0)
+ if (mem_cgroup_disabled())
+ return;
+
+ if (unlikely(i < 0)) {
+ pr_warn_once("%s: stat item index: %d\n", __func__, idx);
return;
+ }
__this_cpu_add(memcg->vmstats_percpu->state[i], val);
memcg_rstat_updated(memcg, memcg_state_val_in_pages(idx, val));
@@ -971,8 +982,10 @@ static unsigned long memcg_page_state_lo
long x;
int i = memcg_stats_index(idx);
- if (i < 0)
+ if (unlikely(i < 0)) {
+ pr_warn_once("%s: stat item index: %d\n", __func__, idx);
return 0;
+ }
x = READ_ONCE(memcg->vmstats->state_local[i]);
#ifdef CONFIG_SMP
@@ -990,8 +1003,10 @@ static void __mod_memcg_lruvec_state(str
struct mem_cgroup *memcg;
int i = memcg_stats_index(idx);
- if (i < 0)
+ if (unlikely(i < 0)) {
+ pr_warn_once("%s: stat item index: %d\n", __func__, idx);
return;
+ }
pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
memcg = pn->memcg;
@@ -1103,8 +1118,13 @@ void __count_memcg_events(struct mem_cgr
{
int index = memcg_events_index(idx);
- if (mem_cgroup_disabled() || index < 0)
+ if (mem_cgroup_disabled())
+ return;
+
+ if (unlikely(index < 0)) {
+ pr_warn_once("%s: event item index: %d\n", __func__, idx);
return;
+ }
memcg_stats_lock();
__this_cpu_add(memcg->vmstats_percpu->events[index], count);
@@ -1116,8 +1136,11 @@ static unsigned long memcg_events(struct
{
int index = memcg_events_index(event);
- if (index < 0)
+ if (unlikely(index < 0)) {
+ pr_warn_once("%s: event item index: %d\n", __func__, event);
return 0;
+ }
+
return READ_ONCE(memcg->vmstats->events[index]);
}
@@ -1125,8 +1148,10 @@ static unsigned long memcg_events_local(
{
int index = memcg_events_index(event);
- if (index < 0)
+ if (unlikely(index < 0)) {
+ pr_warn_once("%s: event item index: %d\n", __func__, event);
return 0;
+ }
return READ_ONCE(memcg->vmstats->events_local[index]);
}
_
Patches currently in -mm which might be from shakeel.butt@xxxxxxxxx are
memcg-simple-cleanup-of-stats-update-functions.patch
memcg-reduce-memory-size-of-mem_cgroup_events_index.patch
memcg-dynamically-allocate-lruvec_stats.patch
memcg-reduce-memory-for-the-lruvec-and-memcg-stats.patch
memcg-cleanup-__mod_memcg_lruvec_state.patch
memcg-pr_warn_once-for-unexpected-events-and-stats.patch
memcg-use-proper-type-for-mod_memcg_state.patch
mm-cleanup-workingset_nodes-in-workingset.patch
