From: Michal Hocko <mhocko@suse.com>
To: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Tejun Heo <tj@kernel.org>, Roman Gushchin <guro@fb.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH 1/7] mm: memcontrol: fix cpuhotplug statistics flushing
Date: Thu, 4 Feb 2021 14:28:52 +0100 [thread overview]
Message-ID: <YBv2lAkaxcPD22dd@dhcp22.suse.cz> (raw)
In-Reply-To: <20210202184746.119084-2-hannes@cmpxchg.org>
On Tue 02-02-21 13:47:40, Johannes Weiner wrote:
> 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.
>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Shakeel has already pointed out Fixes.
> ---
> 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
>
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2021-02-04 13:28 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 18:47 [PATCH 0/7]: mm: memcontrol: switch to rstat Johannes Weiner
2021-02-02 18:47 ` [PATCH 1/7] mm: memcontrol: fix cpuhotplug statistics flushing Johannes Weiner
2021-02-02 22:23 ` Shakeel Butt
2021-02-02 23:07 ` Roman Gushchin
2021-02-03 2:28 ` Roman Gushchin
2021-02-04 19:29 ` Johannes Weiner
2021-02-04 19:34 ` Roman Gushchin
2021-02-05 17:50 ` Johannes Weiner
2021-02-04 13:28 ` Michal Hocko [this message]
2021-02-02 18:47 ` [PATCH 2/7] mm: memcontrol: kill mem_cgroup_nodeinfo() Johannes Weiner
2021-02-02 22:24 ` Shakeel Butt
2021-02-02 23:13 ` Roman Gushchin
2021-02-04 13:29 ` Michal Hocko
2021-02-02 18:47 ` [PATCH 3/7] mm: memcontrol: privatize memcg_page_state query functions Johannes Weiner
2021-02-02 22:26 ` Shakeel Butt
2021-02-02 23:17 ` Roman Gushchin
2021-02-04 13:30 ` Michal Hocko
2021-02-02 18:47 ` [PATCH 4/7] cgroup: rstat: support cgroup1 Johannes Weiner
2021-02-03 1:16 ` Roman Gushchin
2021-02-04 13:39 ` Michal Hocko
2021-02-04 16:01 ` Johannes Weiner
2021-02-04 16:42 ` Michal Hocko
2021-02-02 18:47 ` [PATCH 5/7] cgroup: rstat: punt root-level optimization to individual controllers Johannes Weiner
2021-02-02 18:47 ` [PATCH 6/7] mm: memcontrol: switch to rstat Johannes Weiner
2021-02-03 1:47 ` Roman Gushchin
2021-02-04 16:26 ` Johannes Weiner
2021-02-04 18:45 ` Roman Gushchin
2021-02-04 20:05 ` Johannes Weiner
2021-02-04 14:19 ` Michal Hocko
2021-02-04 16:15 ` Johannes Weiner
2021-02-04 16:44 ` Michal Hocko
2021-02-04 20:28 ` Johannes Weiner
2021-02-05 15:05 ` Michal Hocko
2021-02-05 16:34 ` Johannes Weiner
2021-02-08 14:07 ` Michal Hocko
2021-02-02 18:47 ` [PATCH 7/7] mm: memcontrol: consolidate lruvec stat flushing Johannes Weiner
2021-02-03 2:25 ` Roman Gushchin
2021-02-04 21:44 ` Johannes Weiner
2021-02-04 21:47 ` Roman Gushchin
2021-02-05 15:17 ` Michal Hocko
2021-02-05 17:10 ` Johannes Weiner
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