The memcg hotunplug callback erroneously flushes counts on the local
CPU, not the counts of the CPU going away; those counts will be lost.
Flush the CPU that is actually going away.
Also simplify the code a bit by using mod_memcg_state() and
count_memcg_events() instead of open-coding the upward flush - this is
comparable to how vmstat.c handles hotunplug flushing.
Fixes: a983b5ebee572 ("mm: memcontrol: fix excessive complexity in memory.stat reporting")
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Reviewed-by: Roman Gushchin <guro@xxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
---
mm/memcontrol.c | 35 +++++++++++++++++++++--------------
1 file changed, 21 insertions(+), 14 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ed5cc78a8dbf..8120d565dd79 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2411,45 +2411,52 @@ static void drain_all_stock(struct mem_cgroup *root_memcg)
static int memcg_hotplug_cpu_dead(unsigned int cpu)
{
struct memcg_stock_pcp *stock;
- struct mem_cgroup *memcg, *mi;
+ struct mem_cgroup *memcg;
stock = &per_cpu(memcg_stock, cpu);
drain_stock(stock);
for_each_mem_cgroup(memcg) {
+ struct memcg_vmstats_percpu *statc;
int i;
+ statc = per_cpu_ptr(memcg->vmstats_percpu, cpu);
+
for (i = 0; i < MEMCG_NR_STAT; i++) {
int nid;
- long x;
- x = this_cpu_xchg(memcg->vmstats_percpu->stat[i], 0);
- if (x)
- for (mi = memcg; mi; mi = parent_mem_cgroup(mi))
- atomic_long_add(x, &memcg->vmstats[i]);
+ if (statc->stat[i]) {
+ mod_memcg_state(memcg, i, statc->stat[i]);
+ statc->stat[i] = 0;
+ }
if (i >= NR_VM_NODE_STAT_ITEMS)
continue;
for_each_node(nid) {
+ struct batched_lruvec_stat *lstatc;
struct mem_cgroup_per_node *pn;
+ long x;
pn = mem_cgroup_nodeinfo(memcg, nid);
- x = this_cpu_xchg(pn->lruvec_stat_cpu->count[i], 0);
- if (x)
+ lstatc = per_cpu_ptr(pn->lruvec_stat_cpu, cpu);
+
+ x = lstatc->count[i];
+ lstatc->count[i] = 0;
+
+ if (x) {
do {
atomic_long_add(x, &pn->lruvec_stat[i]);
} while ((pn = parent_nodeinfo(pn, nid)));
+ }
}
}
for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
- long x;
-
- x = this_cpu_xchg(memcg->vmstats_percpu->events[i], 0);
- if (x)
- for (mi = memcg; mi; mi = parent_mem_cgroup(mi))
- atomic_long_add(x, &memcg->vmevents[i]);
+ if (statc->events[i]) {
+ count_memcg_events(memcg, i, statc->events[i]);
+ statc->events[i] = 0;
+ }
}
}
--
2.30.0
