From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tejun Heo Subject: Re: [PATCH 07/12] cgroup: unify cgroup_write_X64() and cgroup_write_string() Date: Tue, 3 Dec 2013 15:41:55 -0500 Message-ID: <20131203204155.GL8277@htj.dyndns.org> References: <1385595759-17656-1-git-send-email-tj@kernel.org> <1385595759-17656-8-git-send-email-tj@kernel.org> <20131128111818.GG2761@dhcp22.suse.cz> <20131129200525.GC21755@mtj.dyndns.org> <20131202095401.GA18838@dhcp22.suse.cz> <20131202133059.GA3626@htj.dyndns.org> <20131202141242.GD18838@dhcp22.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; bh=II49Zeh313tsOJFxwQGdPCgrks9XmDsYj3fS3SUqiHg=; b=K0kP0Pn4rfciDgtWo/vO2v3ayQeCobEjBdU0+VNBC4d3v3XHRLzOKHYlGksVzmpp// 7M6iTYhSiEyJquaBZDfmHlg3ZnYVeTqaaE7bemOyvK1NbNANi6CVjMFY0RKJ4vU0NowZ JplGKHRWm71w16rPzINgpB8w6KEKRukHGSlgyabbb/vIeeShoz5VmkrFRbZwwP3jd583 xDAJQMvxIzoF7s2K6ziO/n8qS+dBcvg8soGZxeS6ektjDjCNDuCClMNEJGjy9drwHVcw cNAPPlzBNw89hHBMpMvov16iconzK0fZxAakwA92z2eGAeH1i8DsZt9lRe+VT+p7NI1+ p7hw== Content-Disposition: inline In-Reply-To: <20131202141242.GD18838-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Michal Hocko Cc: nhorman-2XuSBdqkA4R54TAoqtyWWQ@public.gmane.org, containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, daniel.wagner-98C5kh4wR6ohFhg+JK9F0w@public.gmane.org, hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org Hello, Michal. On Mon, Dec 02, 2013 at 03:12:42PM +0100, Michal Hocko wrote: > I really do not want to add more hacks just to make this use case work. > There are some proposals for more systematic implementation (memory > reserves for oom killer etc.) but that won't interfere with the cgroup > core. > This one just looks trivial so I was thinking whether we can keep the > !allocating write as before. It is nothing I would insist on, though. So > I will leave the decision on you. So, I'm just gonna commit the patches as-is because I can't really see how this is anything which can work in any reasonable way. As it currently stands, the userland wouldn't even be able to read any knob. Wouldn't it at least need to do that? Actually, the answer to that question doesn't even matter because "no" would mean that the OOM notification, however it's done, can't depend on the userland being able to read *any* knob, which in turn is likely to constrain and distort the notification mechanism itself. These things are all connected and this type of bad decisions propagates through the whole stack. In case this *really* is necessary, let's please do it in a separate patch with rationale and detailed explanation of actual usage. Thanks. -- tejun