Re: [v3 PATCH 10/11] mm: memcontrol: reparent nr_deferred when memcg offline
From: Kirill Tkhai <hidden>
Date: 2021-01-06 11:36:23
Also in:
linux-fsdevel, lkml
On 06.01.2021 01:58, Yang Shi wrote:
quoted hunk ↗ jump to hunk
Now shrinker's nr_deferred is per memcg for memcg aware shrinkers, add to parent's corresponding nr_deferred when memcg offline. Signed-off-by: Yang Shi <redacted> --- include/linux/memcontrol.h | 1 + mm/memcontrol.c | 1 + mm/vmscan.c | 29 +++++++++++++++++++++++++++++ 3 files changed, 31 insertions(+)diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 5599082df623..d1e52e916cc2 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h@@ -1586,6 +1586,7 @@ extern int memcg_alloc_shrinker_info(struct mem_cgroup *memcg); extern void memcg_free_shrinker_info(struct mem_cgroup *memcg); extern void memcg_set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id); +extern void memcg_reparent_shrinker_deferred(struct mem_cgroup *memcg); #else #define mem_cgroup_sockets_enabled 0 static inline void mem_cgroup_sk_alloc(struct sock *sk) { };diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 126f1fd550c8..19e555675582 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c@@ -5284,6 +5284,7 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) page_counter_set_low(&memcg->memory, 0); memcg_offline_kmem(memcg); + memcg_reparent_shrinker_deferred(memcg); wb_memcg_offline(memcg); drain_all_stock(memcg);diff --git a/mm/vmscan.c b/mm/vmscan.c index d9795fb0f1c5..71056057d26d 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c@@ -396,6 +396,35 @@ static long set_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker, return atomic_long_add_return(nr, &info->nr_deferred[shrinker->id]); } +void memcg_reparent_shrinker_deferred(struct mem_cgroup *memcg) +{ + int i, nid; + long nr; + struct mem_cgroup *parent; + struct memcg_shrinker_info *child_info, *parent_info; + + parent = parent_mem_cgroup(memcg); + if (!parent) + parent = root_mem_cgroup; + + /* Prevent from concurrent shrinker_info expand */ + down_read(&shrinker_rwsem); + for_each_node(nid) { + child_info = rcu_dereference_protected( + memcg->nodeinfo[nid]->shrinker_info, + true); + parent_info = rcu_dereference_protected( + parent->nodeinfo[nid]->shrinker_info, + true);
Simple assignment can't take such lots of space, we have to do something with that.
Number of these
rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info, true)
became too big, and we can't allow every of them takes 3 lines.
We should introduce a short helper to dereferrence this, so we will be able to give
out attention to really difficult logic instead of wasting it on parsing this.
child_info = memcg_shrinker_info(memcg, nid);
or
child_info = memcg_shrinker_info_protected(memcg, nid);
Both of them fit in single line.
struct memcg_shrinker_info *memcg_shrinker_info_protected(
struct mem_cgroup *memcg, int nid)
{
return rcu_dereference_protected(memcg->nodeinfo[nid]->shrinker_info,
lockdep_assert_held(&shrinker_rwsem));
}
+ for (i = 0; i < shrinker_nr_max; i++) {
+ nr = atomic_long_read(&child_info->nr_deferred[i]);
+ atomic_long_add(nr,
+ &parent_info->nr_deferred[i]);Why new line is here? In case of you merge it up, it will be even shorter then previous line.
+ }
+ }
+ up_read(&shrinker_rwsem);
+}
+
static bool cgroup_reclaim(struct scan_control *sc)
{
return sc->target_mem_cgroup;