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[201.92.249.168]) by smtp.gmail.com with ESMTPSA id q5sm13241324qte.38.2019.10.15.07.09.54 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 15 Oct 2019 07:09:56 -0700 (PDT) Subject: Re: [PATCH] hugetlb: Add nohugepages parameter to prevent hugepages creation To: Michal Hocko , Qian Cai Cc: Guilherme Piccoli , linux-mm@kvack.org, mike.kravetz@oracle.com, linux-kernel@vger.kernel.org, Jay Vosburgh , "Guilherme G. Piccoli" References: <4641B95A-6DD8-4E8A-AD53-06E7B72D956C@lca.pw> <20191015121803.GB24932@dhcp22.suse.cz> <20191015140508.GJ317@dhcp22.suse.cz> From: "Guilherme G. Piccoli" Message-ID: <2d593c95-3c69-8f50-17ff-223bd607caf1@gpiccoli.net> Date: Tue, 15 Oct 2019 11:09:53 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20191015140508.GJ317@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.006411, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 10/15/19 11:05 AM, Michal Hocko wrote: > On Tue 15-10-19 10:58:36, Guilherme G. Piccoli wrote: >> On 10/15/19 9:18 AM, Michal Hocko wrote: >>> I do agree with Qian Cai here. Kdump kernel requires a very tailored >>> environment considering it is running in a very restricted >>> configuration. The hugetlb pre-allocation sounds like a tooling problem >>> and should be fixed at that layer. >>> >> >> Hi Michal, thanks for your response. Can you suggest me a current way of >> preventing hugepages for being created, using userspace? The goal for this >> patch is exactly this, introduce such a way. > > Simply restrict the environment to not allocate any hugepages? Kdump > already controls the kernel command line and it also starts only a very > minimal subset of services. So who is allocating those hugepages? > sysctls should be already excluded by default as Qian mentioned. > OK, thanks Michal and Qian, I'll try to make things work from kdump perspective. The trick part is exactly preventing the sysctl to get applied heh Cheers, Guilherme