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[71.184.117.43]) by smtp.gmail.com with ESMTPSA id q64sm5404232qkb.32.2019.10.11.16.35.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 11 Oct 2019 16:35:58 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable From: Qian Cai Mime-Version: 1.0 (1.0) Subject: Re: [PATCH] hugetlb: Add nohugepages parameter to prevent hugepages creation Date: Fri, 11 Oct 2019 19:35:57 -0400 Message-Id: <36C2B5DF-7F21-42C6-BA77-6D86EDCB6BB3@lca.pw> References: <20191011223955.1435-1-gpiccoli@canonical.com> Cc: linux-mm@kvack.org, mike.kravetz@oracle.com, linux-kernel@vger.kernel.org, jay.vosburgh@canonical.com, kernel@gpiccoli.net In-Reply-To: <20191011223955.1435-1-gpiccoli@canonical.com> To: "Guilherme G. Piccoli" X-Mailer: iPhone Mail (17A860) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000057, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: > On Oct 11, 2019, at 6:40 PM, Guilherme G. Piccoli = wrote: >=20 > Kdump kernels won't benefit from hugepages - in fact it's quite opposite, > it may be the case hugepages on kdump kernel can lead to OOM if kernel > gets unable to allocate demanded pages due to the fact the preallocated > hugepages are consuming a lot of memory. >=20 > This patch proposes a new kernel parameter to prevent the creation of > HugeTLB hugepages - we currently don't have a way to do that. We can > even have kdump scripts removing the kernel command-line options to > set hugepages, but it's not straightforward to prevent sysctl/sysfs > configuration, given it happens in later boot or anytime when the > system is running. Typically, kdump kernel has its own initramfs, and don=E2=80=99t even need t= o mount a rootfs, so I can=E2=80=99t see how sysfs/sysctl is relevant here.=