From: Muchun Song <songmuchun@bytedance.com> To: hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, akpm@linux-foundation.org Cc: cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Muchun Song <songmuchun@bytedance.com> Subject: [PATCH 3/4] mm: memcontrol: bail out early when id is zero Date: Sat, 13 Feb 2021 01:01:58 +0800 [thread overview] Message-ID: <20210212170159.32153-3-songmuchun@bytedance.com> (raw) In-Reply-To: <20210212170159.32153-1-songmuchun@bytedance.com> The memcg ID cannot be zero, but we can pass zero to mem_cgroup_from_id, so idr_find() is pointless and wastes CPU cycles. Signed-off-by: Muchun Song <songmuchun@bytedance.com> --- mm/memcontrol.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a3f26522765a..68ed4b297c13 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5173,6 +5173,9 @@ static inline void mem_cgroup_id_put(struct mem_cgroup *memcg) struct mem_cgroup *mem_cgroup_from_id(unsigned short id) { WARN_ON_ONCE(!rcu_read_lock_held()); + /* The memcg ID cannot be zero. */ + if (id == 0) + return NULL; return idr_find(&mem_cgroup_idr, id); } -- 2.11.0
WARNING: multiple messages have this Message-ID (diff)
From: Muchun Song <songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org> To: hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, vdavydov.dev-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Muchun Song <songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org> Subject: [PATCH 3/4] mm: memcontrol: bail out early when id is zero Date: Sat, 13 Feb 2021 01:01:58 +0800 [thread overview] Message-ID: <20210212170159.32153-3-songmuchun@bytedance.com> (raw) In-Reply-To: <20210212170159.32153-1-songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org> The memcg ID cannot be zero, but we can pass zero to mem_cgroup_from_id, so idr_find() is pointless and wastes CPU cycles. Signed-off-by: Muchun Song <songmuchun-EC8Uxl6Npydl57MIdRCFDg@public.gmane.org> --- mm/memcontrol.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index a3f26522765a..68ed4b297c13 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5173,6 +5173,9 @@ static inline void mem_cgroup_id_put(struct mem_cgroup *memcg) struct mem_cgroup *mem_cgroup_from_id(unsigned short id) { WARN_ON_ONCE(!rcu_read_lock_held()); + /* The memcg ID cannot be zero. */ + if (id == 0) + return NULL; return idr_find(&mem_cgroup_idr, id); } -- 2.11.0
next prev parent reply other threads:[~2021-02-12 17:03 UTC|newest] Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-02-12 17:01 [PATCH 1/4] mm: memcontrol: remove memcg check from memcg_oom_recover Muchun Song 2021-02-12 17:01 ` Muchun Song 2021-02-12 17:01 ` [PATCH 2/4] mm: memcontrol: add missing memcg_oom_recover() when uncharge slab page Muchun Song 2021-02-12 17:01 ` Muchun Song 2021-02-15 9:37 ` Michal Hocko 2021-02-15 9:37 ` Michal Hocko 2021-02-12 17:01 ` Muchun Song [this message] 2021-02-12 17:01 ` [PATCH 3/4] mm: memcontrol: bail out early when id is zero Muchun Song 2021-02-15 9:39 ` Michal Hocko 2021-02-15 9:39 ` Michal Hocko 2021-02-15 10:09 ` [External] " Muchun Song 2021-02-15 10:09 ` Muchun Song 2021-02-15 10:09 ` Muchun Song 2021-02-15 10:27 ` Michal Hocko 2021-02-15 10:27 ` Michal Hocko 2021-02-15 11:34 ` Muchun Song 2021-02-15 11:34 ` Muchun Song 2021-02-15 11:34 ` Muchun Song 2021-02-12 17:01 ` [PATCH 4/4] mm: memcontrol: fix swap uncharge on cgroup v2 Muchun Song 2021-02-12 17:01 ` Muchun Song 2021-02-12 18:56 ` Shakeel Butt 2021-02-12 18:56 ` Shakeel Butt 2021-02-13 6:48 ` [External] " Muchun Song 2021-02-13 6:48 ` Muchun Song 2021-02-16 17:16 ` Shakeel Butt 2021-02-16 17:16 ` Shakeel Butt 2021-02-16 17:16 ` Shakeel Butt 2021-02-15 9:47 ` Michal Hocko 2021-02-15 9:47 ` Michal Hocko 2021-02-15 10:15 ` [External] " Muchun Song 2021-02-15 10:15 ` Muchun Song 2021-02-15 10:15 ` Muchun Song 2021-02-15 10:24 ` Michal Hocko 2021-02-15 10:24 ` Michal Hocko 2021-02-16 16:59 ` Johannes Weiner 2021-02-16 17:17 ` Shakeel Butt 2021-02-16 17:17 ` Shakeel Butt 2021-02-16 17:17 ` Shakeel Butt 2021-02-16 17:19 ` Michal Hocko 2021-02-16 17:19 ` Michal Hocko 2021-02-16 17:28 ` Johannes Weiner 2021-02-16 17:28 ` Johannes Weiner 2021-02-17 5:15 ` [External] " Muchun Song 2021-02-17 5:15 ` Muchun Song 2021-02-17 5:15 ` Muchun Song 2021-02-17 5:11 ` Muchun Song 2021-02-17 5:11 ` Muchun Song 2021-02-17 5:11 ` Muchun Song 2021-02-15 9:24 ` [PATCH 1/4] mm: memcontrol: remove memcg check from memcg_oom_recover Michal Hocko 2021-02-15 9:24 ` Michal Hocko
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