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[209.132.180.67]) by mx.google.com with ESMTP id bt28si4435069edb.270.2019.11.14.11.21.00; Thu, 14 Nov 2019 11:21:25 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=fail header.i=@gmail.com header.s=20161025 header.b=byTtSXKQ; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726655AbfKNTUW (ORCPT + 99 others); Thu, 14 Nov 2019 14:20:22 -0500 Received: from mail-qk1-f196.google.com ([209.85.222.196]:33216 "EHLO mail-qk1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726098AbfKNTUW (ORCPT ); Thu, 14 Nov 2019 14:20:22 -0500 Received: by mail-qk1-f196.google.com with SMTP id 71so6035049qkl.0; Thu, 14 Nov 2019 11:20:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=Ad+hImqgLDxypIEINMZpS4Tr/4Mgv7yIFC4Nbt2V9kg=; b=byTtSXKQQYePQfHDLVfvtbTfxb+feN2Rw10WG0dnLqlQHjnp6ZqhpFGPYiTJtn9lDD 6SrXLdyjN+S+8zKLupJ0J6AOFKhKFCdKMEB0XC3KSHz3eaXrxnWfHgS8f5fTJbaHzaBw nICTABqMxTHdOrmtN6iofLY9mxUzOMb2zmHAp8FT4UsTjOojgCJymb3q1NuHBdnFW9Li Uiq6x+NEu+2qVNn+pQXfevOoGLxsvDTu+ti1pPhty9u+5ujN/s/K1Sb/phspRfgXDRWZ 9oZChaZKJI2FU49/FO/+OCDXzbOaw5PJmWhv/qzB+P/UWgcL+2sDK8CpqPNYJ0QyXAJ6 Y2bA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to:user-agent; bh=Ad+hImqgLDxypIEINMZpS4Tr/4Mgv7yIFC4Nbt2V9kg=; b=OpZ4/sLy29V0A8WrBiqJX2o7GbQRG/vn6JNLB0Eg8jbnbTUYW2Dma7M3JZT9gL9Ud8 eI6TD3238UW2bgmz7WdOnV/+f0jowrZUL1kiXaK1NQqJPdzUkhjV2D5yGLvRCqbnBkIx 61wcs7DHF3BRUKpxtEgDBBavp56kKIr7e7gk1LNl9jpbbCg8CTHm7HN5x3lgD+U776gg Ri2LeTdNjvxUW74TPh8wCcKnkyDZWDMFyn4RZvEmG9FwTEZKwW4nkt9G4Uz/ESeYymTH 5spH9spU1Cr8eHF3cgMR+MYT6oPOpl96SvvXR9Ztq723E4aIn+pAYHCsbRVDpoqWtJx6 jdeQ== X-Gm-Message-State: APjAAAWVtNd/wqUIZu8b2AI+6/MIVh8ULzFe/zO75IV7uGvB0s8rkrYt tGSO1y6kym7k/Q5vRmFrtT8= X-Received: by 2002:ae9:eb94:: with SMTP id b142mr9178344qkg.450.1573759221143; Thu, 14 Nov 2019 11:20:21 -0800 (PST) Received: from localhost ([2620:10d:c091:500::2:69f2]) by smtp.gmail.com with ESMTPSA id h25sm2893772qka.117.2019.11.14.11.20.19 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 14 Nov 2019 11:20:20 -0800 (PST) Date: Thu, 14 Nov 2019 11:20:18 -0800 From: Tejun Heo To: Michal Hocko Cc: Roman Gushchin , Michal =?iso-8859-1?Q?Koutn=FD?= , "linux-mm@kvack.org" , Andrew Morton , Johannes Weiner , "linux-kernel@vger.kernel.org" , Kernel Team , "stable@vger.kernel.org" Subject: Re: [PATCH 1/2] mm: memcg: switch to css_tryget() in get_mem_cgroup_from_mm() Message-ID: <20191114192018.GJ4163745@devbig004.ftw2.facebook.com> References: <20191106225131.3543616-1-guro@fb.com> <20191113162934.GF19372@blackbody.suse.cz> <20191113170823.GA12464@castle.DHCP.thefacebook.com> <20191114191657.GN20866@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191114191657.GN20866@dhcp22.suse.cz> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Thu, Nov 14, 2019 at 08:16:57PM +0100, Michal Hocko wrote: > Then what is the point of this function and what about all other users? It is useful for controlling admissions of new userspace visible uses - e.g. a tracepoint shouldn't be allowed to be attached to a cgroup which has already been deleted. We're just using it too liberally. Thanks. -- tejun