The patch titled Subject: mm: memcontrol: flush percpu vmevents before releasing memcg has been removed from the -mm tree. Its filename was mm-memcontrol-flush-percpu-vmevents-before-releasing-memcg.patch

This patch was dropped because an updated version will be merged

------------------------------------------------------ From: Roman Gushchin guro@fb.com Subject: mm: memcontrol: flush percpu vmevents before releasing memcg

Similar to vmstats, percpu caching of local vmevents leads to an accumulation of errors on non-leaf levels. This happens because some leftovers may remain in percpu caches, so that they are never propagated up by the cgroup tree and just disappear into nonexistence with on releasing of the memory cgroup.

To fix this issue let's accumulate and propagate percpu vmevents values before releasing the memory cgroup similar to what we're doing with vmstats.

Since on cpu hotplug we do flush percpu vmstats anyway, we can iterate only over online cpus.

Link: http://lkml.kernel.org/r/20190812233754.2570543-1-guro@fb.com Fixes: 42a300353577 ("mm: memcontrol: fix recursive statistics correctness & scalabilty") Signed-off-by: Roman Gushchin guro@fb.com Acked-by: Michal Hocko mhocko@suse.com Cc: Johannes Weiner hannes@cmpxchg.org Cc: Vladimir Davydov vdavydov.dev@gmail.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/memcontrol.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-)

--- a/mm/memcontrol.c~mm-memcontrol-flush-percpu-vmevents-before-releasing-memcg +++ a/mm/memcontrol.c @@ -3336,6 +3336,25 @@ static void memcg_flush_percpu_vmstats(s } }

+static void memcg_flush_percpu_vmevents(struct mem_cgroup *memcg) +{ + unsigned long events[NR_VM_EVENT_ITEMS]; + struct mem_cgroup *mi; + int cpu, i; + + for (i = 0; i < NR_VM_EVENT_ITEMS; i++) + events[i] = 0; + + for_each_online_cpu(cpu) + for (i = 0; i < NR_VM_EVENT_ITEMS; i++) + events[i] += raw_cpu_read( + memcg->vmstats_percpu->events[i]); + + for (mi = memcg; mi; mi = parent_mem_cgroup(mi)) + for (i = 0; i < NR_VM_EVENT_ITEMS; i++) + atomic_long_add(events[i], &mi->vmevents[i]); +} + static void memcg_offline_kmem(struct mem_cgroup *memcg) { struct cgroup_subsys_state *css; @@ -4737,10 +4756,11 @@ static void __mem_cgroup_free(struct mem int node;

/* - * Flush percpu vmstats to guarantee the value correctness + * Flush percpu vmstats and vmevents to guarantee the value correctness * on parent's and all ancestor levels. */ memcg_flush_percpu_vmstats(memcg, false); + memcg_flush_percpu_vmevents(memcg); for_each_node(node) free_mem_cgroup_per_node_info(memcg, node); free_percpu(memcg->vmstats_percpu); _

Patches currently in -mm which might be from guro@fb.com are

mm-memcontrol-switch-to-rcu-protection-in-drain_all_stock.patch