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| author | Roman Gushchin <guro@fb.com> | 2020-08-06 23:20:28 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-08-07 11:33:24 -0700 |
| commit | d648bcc7fe65f09ecd19091f68395dfb3b7a87c8 (patch) | |
| tree | 8ed3c4cbf63de0362a7142ec0c6c74cc52586f49 /mm/memcontrol.c | |
| parent | ea3271f7196c65ae5d3e1c7b3f733892c017dbd6 (diff) | |
| download | linux-d648bcc7fe65f09ecd19091f68395dfb3b7a87c8.tar.gz | |
mm: kmem: make memcg_kmem_enabled() irreversible
Historically the kernel memory accounting was an opt-in feature, which could be enabled for individual cgroups. But now it's not true, and it's on by default both on cgroup v1 and cgroup v2. And as long as a user has at least one non-root memory cgroup, the kernel memory accounting is on. So in most setups it's either always on (if memory cgroups are in use and kmem accounting is not disabled), either always off (otherwise). memcg_kmem_enabled() is used in many places to guard the kernel memory accounting code. If memcg_kmem_enabled() can reverse from returning true to returning false (as now), we can't rely on it on release paths and have to check if it was on before. If we'll make memcg_kmem_enabled() irreversible (always returning true after returning it for the first time), it'll make the general logic more simple and robust. It also will allow to guard some checks which otherwise would stay unguarded. Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org> Signed-off-by: Roman Gushchin <guro@fb.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Tested-by: Naresh Kamboju <naresh.kamboju@linaro.org> Reviewed-by: Shakeel Butt <shakeelb@google.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Link: http://lkml.kernel.org/r/20200702180926.1330769-1-guro@fb.com Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 8 |
1 files changed, 2 insertions, 6 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 8cc617ede7e2..24892a14cc75 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3416,7 +3416,8 @@ static int memcg_online_kmem(struct mem_cgroup *memcg) if (memcg_id < 0) return memcg_id; - static_branch_inc(&memcg_kmem_enabled_key); + static_branch_enable(&memcg_kmem_enabled_key); + /* * A memory cgroup is considered kmem-online as soon as it gets * kmemcg_id. Setting the id after enabling static branching will @@ -3486,11 +3487,6 @@ static void memcg_free_kmem(struct mem_cgroup *memcg) /* css_alloc() failed, offlining didn't happen */ if (unlikely(memcg->kmem_state == KMEM_ONLINE)) memcg_offline_kmem(memcg); - - if (memcg->kmem_state == KMEM_ALLOCATED) { - WARN_ON(!list_empty(&memcg->kmem_caches)); - static_branch_dec(&memcg_kmem_enabled_key); - } } #else static int memcg_online_kmem(struct mem_cgroup *memcg) |