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d="scan'208";a="5118045" Received: from mail-lj1-f198.google.com ([209.85.208.198]) by smtp1.ucr.edu with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 30 Aug 2019 15:28:29 -0700 Received: by mail-lj1-f198.google.com with SMTP id y25so1010873lji.21 for ; Fri, 30 Aug 2019 15:27:21 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=zLm09boqVLNebbJn0KRM9g9k9tAtM8q9U95oJU1h0L0=; b=nVbHfO/IM+K7otGk3ziEKTWlTsAlVAQTUAbYppikjkPrnhoFGaim5NHPaOGHXrCEGq 2ijruE98Ue+0U3q2xaUEDTlyo6dXqKibcFf8xYGni1fe9tZUjIO+SQLNNraZmYASF9BJ Og0Vx6srIYVpOnzPDj01Y84u5I8CUyGpWCjq/zWoR1ftjCiMC475CUyhsQZhgAcHxKh0 od9NoyHUYsOz9FjZml46krWUePDsVebbx/G6K9GKckf5TCN3p+DYUb1fuz3w+e7fiF6D kJEGYEskhHpidzCkmK8HGF3oTq2WS1PeBwSNMZPydNTFztjb0YUHaFX5ZhZe4hpihMx/ 8Vcg== X-Gm-Message-State: APjAAAXsZl9s06c9htR8/SvkJpBsryTMjcoJNerEJoah1b8yqLBEQNuQ Ykzb3fQ0TAVUkV8h56pbXFuNfw1odXnWkzwCFkqLvUGCb1VZaOe7hwi8Kqm/1Se9yNnySGRxYUW IaEpBd+96xPvCWsoCY1O4NGz7NO3e X-Received: by 2002:a19:2d19:: with SMTP id k25mr11524774lfj.76.1567204039644; Fri, 30 Aug 2019 15:27:19 -0700 (PDT) X-Google-Smtp-Source: APXvYqxNwVPvOdN/tveaY5mDrcDGRnQDZr8owb4Bj/v//Ng1I8rWXAU6aT8pAFp3c8BU1Pct5O5eSmP/cI28qOpREA4= X-Received: by 2002:a19:2d19:: with SMTP id k25mr11524763lfj.76.1567204039450; Fri, 30 Aug 2019 15:27:19 -0700 (PDT) MIME-Version: 1.0 References: <20190822062210.18649-1-yzhai003@ucr.edu> <20190822070550.GA12785@dhcp22.suse.cz> <20190822201200.GP12785@dhcp22.suse.cz> In-Reply-To: <20190822201200.GP12785@dhcp22.suse.cz> From: Yizhuo Zhai Date: Fri, 30 Aug 2019 15:27:50 -0700 Message-ID: Subject: Re: [PATCH] mm/memcg: return value of the function mem_cgroup_from_css() is not checked To: Michal Hocko Cc: Chengyu Song , Zhiyun Qian , Johannes Weiner , Vladimir Davydov , cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000032, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Our tool did not trace back the whole path, so, now we could say it might happen. On Thu, Aug 22, 2019 at 1:12 PM Michal Hocko wrote: > > On Thu 22-08-19 13:07:17, Yizhuo Zhai wrote: > > This will happen if variable "wb->memcg_css" is NULL. This case is reported > > by our analysis tool. > > Does your tool report the particular call path and conditions when that > happen? Or is it just a "it mignt happen" kinda thing? > > > Since the function mem_cgroup_wb_domain() is visible to the global, we > > cannot control caller's behavior. > > I am sorry but I do not understand what is this supposed to mean. > -- > Michal Hocko > SUSE Labs -- Kind Regards, Yizhuo Zhai Computer Science, Graduate Student University of California, Riverside