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Tue, 23 Feb 2021 01:14:04 -0800 (PST) Received: from localhost.localdomain ([139.177.225.236]) by smtp.gmail.com with ESMTPSA id c18sm19816267pgm.88.2021.02.23.01.14.00 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 Feb 2021 01:14:04 -0800 (PST) From: Muchun Song To: hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, akpm@linux-foundation.org, guro@fb.com, shakeelb@google.com Cc: cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Muchun Song Subject: [PATCH] mm: memcontrol: fix get_active_memcg return value Date: Tue, 23 Feb 2021 17:11:01 +0800 Message-Id: <20210223091101.42150-1-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) MIME-Version: 1.0 X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: E14EA407F8E8 X-Stat-Signature: 76jz1ifswto85cmoeth35azk6fmpep9i Received-SPF: none (bytedance.com>: No applicable sender policy available) receiver=imf02; identity=mailfrom; envelope-from=""; helo=mail-pf1-f176.google.com; client-ip=209.85.210.176 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1614071633-379407 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: We use a global percpu int_active_memcg variable to store the remote memcg when we are in the interrupt context. But get_active_memcg always return the current->active_memcg or root_mem_cgroup. The remote memcg (set in the interrupt context) is ignored. This is not what we want. So fix it. Fixes: 37d5985c003d ("mm: kmem: prepare remote memcg charging infra for i= nterrupt contexts") Signed-off-by: Muchun Song --- mm/memcontrol.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index be6bc5044150..bbe25655f7eb 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1061,13 +1061,9 @@ static __always_inline struct mem_cgroup *get_acti= ve_memcg(void) =20 rcu_read_lock(); memcg =3D active_memcg(); - if (memcg) { - /* current->active_memcg must hold a ref. */ - if (WARN_ON_ONCE(!css_tryget(&memcg->css))) - memcg =3D root_mem_cgroup; - else - memcg =3D current->active_memcg; - } + /* remote memcg must hold a ref. */ + if (memcg && WARN_ON_ONCE(!css_tryget(&memcg->css))) + memcg =3D root_mem_cgroup; rcu_read_unlock(); =20 return memcg; --=20 2.11.0