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[209.85.220.65]) by mx.google.com with SMTPS id r130sor9137124yba.43.2019.06.25.17.15.59 for (Google Transport Security); Tue, 25 Jun 2019 17:15:59 -0700 (PDT) Received-SPF: pass (google.com: domain of shakeelb@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=pVlUNDcM; spf=pass (google.com: domain of shakeelb@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=shakeelb@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=9hBC31XsM1drX/BZAp0N2OzT0r+e6co+lkmZ6G0GOVU=; b=pVlUNDcM4cTi+agb1ezQeSRdpds872gA7cb6ZJ+baveCQCZw167X+Pb0NoSrYCPnIZ sf2SLj7IntgrbvnK4d70pRjkOHGKLkGjpCUUeY1KiNj4MKlhKC7A60xtgR4RarZVhHa8 wUZY/HAv8uD8BwX9pcaLVVV9tVpVaTKtHLevMa/qA4Y4yPsSIy/xJzezpaGNRWYRP9dL rUx+O8OaqM4GcgiHUT/QEEjFbkksKz10UfVJ98MwhivQPhcj7ocX9O1xHW8OSBY7TaUw YHKHz2eNMBMhLFeUUtjp5QOHRhrZ9fxu2wmFJEC2OJjqXK3sJenC0N1OVW3pJNyS1pxO BwdA== X-Google-Smtp-Source: APXvYqziwXiEu45zHzvz6AOVywxIKSFUF9xqlnDZnM9NN4/TdLcixitnoMQV0xS/KG+Sf7SbappnvvAohrHdZMKzwm8= X-Received: by 2002:a25:a107:: with SMTP id z7mr790646ybh.165.1561508159394; Tue, 25 Jun 2019 17:15:59 -0700 (PDT) MIME-Version: 1.0 References: <20190611231813.3148843-1-guro@fb.com> <20190611231813.3148843-10-guro@fb.com> In-Reply-To: <20190611231813.3148843-10-guro@fb.com> From: Shakeel Butt Date: Tue, 25 Jun 2019 17:15:48 -0700 Message-ID: Subject: Re: [PATCH v7 09/10] mm: stop setting page->mem_cgroup pointer for slab pages To: Roman Gushchin Cc: Andrew Morton , Vladimir Davydov , Linux MM , LKML , Kernel Team , Johannes Weiner , Waiman Long Content-Type: text/plain; charset="UTF-8" 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: On Tue, Jun 11, 2019 at 4:18 PM Roman Gushchin wrote: > > Every slab page charged to a non-root memory cgroup has a pointer > to the memory cgroup and holds a reference to it, which protects > a non-empty memory cgroup from being released. At the same time > the page has a pointer to the corresponding kmem_cache, and also > hold a reference to the kmem_cache. And kmem_cache by itself > holds a reference to the cgroup. > > So there is clearly some redundancy, which allows to stop setting > the page->mem_cgroup pointer and rely on getting memcg pointer > indirectly via kmem_cache. Further it will allow to change this > pointer easier, without a need to go over all charged pages. > > So let's stop setting page->mem_cgroup pointer for slab pages, > and stop using the css refcounter directly for protecting > the memory cgroup from going away. Instead rely on kmem_cache > as an intermediate object. > > Make sure that vmstats and shrinker lists are working as previously, > as well as /proc/kpagecgroup interface. > > Signed-off-by: Roman Gushchin > Acked-by: Vladimir Davydov Reviewed-by: Shakeel Butt