This is a note to let you know that I've just added the patch titled
memcg: unify memcg stat flushing
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
memcg-unify-memcg-stat-flushing.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From fd25a9e0e23b995fd0ba5e2f00a1099452cbc3cf Mon Sep 17 00:00:00 2001
From: Shakeel Butt <shakeelb@xxxxxxxxxx>
Date: Fri, 5 Nov 2021 13:37:34 -0700
Subject: memcg: unify memcg stat flushing
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From: Shakeel Butt <shakeelb@xxxxxxxxxx>
commit fd25a9e0e23b995fd0ba5e2f00a1099452cbc3cf upstream.
The memcg stats can be flushed in multiple context and potentially in
parallel too. For example multiple parallel user space readers for
memcg stats will contend on the rstat locks with each other. There is
no need for that. We just need one flusher and everyone else can
benefit.
In addition after aa48e47e3906 ("memcg: infrastructure to flush memcg
stats") the kernel periodically flush the memcg stats from the root, so,
the other flushers will potentially have much less work to do.
Link: https://lkml.kernel.org/r/20211001190040.48086-2-shakeelb@xxxxxxxxxx
Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: "Michal Koutný" <mkoutny@xxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Ivan Babrou <ivan@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -660,12 +660,14 @@ static inline void memcg_rstat_updated(s
static void __mem_cgroup_flush_stats(void)
{
- if (!spin_trylock(&stats_flush_lock))
+ unsigned long flag;
+
+ if (!spin_trylock_irqsave(&stats_flush_lock, flag))
return;
cgroup_rstat_flush_irqsafe(root_mem_cgroup->css.cgroup);
atomic_set(&stats_flush_threshold, 0);
- spin_unlock(&stats_flush_lock);
+ spin_unlock_irqrestore(&stats_flush_lock, flag);
}
void mem_cgroup_flush_stats(void)
@@ -1461,7 +1463,7 @@ static char *memory_stat_format(struct m
*
* Current memory state:
*/
- cgroup_rstat_flush(memcg->css.cgroup);
+ mem_cgroup_flush_stats();
for (i = 0; i < ARRAY_SIZE(memory_stats); i++) {
u64 size;
@@ -3554,8 +3556,7 @@ static unsigned long mem_cgroup_usage(st
unsigned long val;
if (mem_cgroup_is_root(memcg)) {
- /* mem_cgroup_threshold() calls here from irqsafe context */
- cgroup_rstat_flush_irqsafe(memcg->css.cgroup);
+ mem_cgroup_flush_stats();
val = memcg_page_state(memcg, NR_FILE_PAGES) +
memcg_page_state(memcg, NR_ANON_MAPPED);
if (swap)
@@ -3936,7 +3937,7 @@ static int memcg_numa_stat_show(struct s
int nid;
struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
- cgroup_rstat_flush(memcg->css.cgroup);
+ mem_cgroup_flush_stats();
for (stat = stats; stat < stats + ARRAY_SIZE(stats); stat++) {
seq_printf(m, "%s=%lu", stat->name,
@@ -4008,7 +4009,7 @@ static int memcg_stat_show(struct seq_fi
BUILD_BUG_ON(ARRAY_SIZE(memcg1_stat_names) != ARRAY_SIZE(memcg1_stats));
- cgroup_rstat_flush(memcg->css.cgroup);
+ mem_cgroup_flush_stats();
for (i = 0; i < ARRAY_SIZE(memcg1_stats); i++) {
unsigned long nr;
@@ -4511,7 +4512,7 @@ void mem_cgroup_wb_stats(struct bdi_writ
struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css);
struct mem_cgroup *parent;
- cgroup_rstat_flush_irqsafe(memcg->css.cgroup);
+ mem_cgroup_flush_stats();
*pdirty = memcg_page_state(memcg, NR_FILE_DIRTY);
*pwriteback = memcg_page_state(memcg, NR_WRITEBACK);
@@ -6394,7 +6395,7 @@ static int memory_numa_stat_show(struct
int i;
struct mem_cgroup *memcg = mem_cgroup_from_seq(m);
- cgroup_rstat_flush(memcg->css.cgroup);
+ mem_cgroup_flush_stats();
for (i = 0; i < ARRAY_SIZE(memory_stats); i++) {
int nid;
Patches currently in stable-queue which might be from shakeelb@xxxxxxxxxx are
queue-5.15/memcg-unify-memcg-stat-flushing.patch
queue-5.15/memcg-flush-stats-only-if-updated.patch
queue-5.15/memcg-better-bounds-on-the-memcg-stats-updates.patch
