[PATCH 1/8] mm: memcontrol: fix cpuhotplug statistics flushing
From: Johannes Weiner <hannes@cmpxchg.org>
Date: 2021-02-05 18:32:36
Also in:
linux-mm, lkml
Subsystem:
control group - memory resource controller (memcg), memory management, the rest · Maintainers:
Johannes Weiner, Michal Hocko, Roman Gushchin, Shakeel Butt, Andrew Morton, Linus Torvalds
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@cmpxchg.org>
Reviewed-by: Shakeel Butt <redacted>
Reviewed-by: Roman Gushchin <redacted>
Acked-by: Michal Hocko <mhocko@suse.com>
---
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