linux-kernel - Re: [PATCH] hugetlb: Add nohugepages parameter to prevent hugepages creation

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Message-ID: <20191015140508.GJ317@dhcp22.suse.cz>
Date:   Tue, 15 Oct 2019 16:05:08 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     "Guilherme G. Piccoli" <guilherme@...ccoli.net>
Cc:     Guilherme Piccoli <gpiccoli@...onical.com>, Qian Cai <cai@....pw>,
        linux-mm@...ck.org, mike.kravetz@...cle.com,
        linux-kernel@...r.kernel.org,
        Jay Vosburgh <jay.vosburgh@...onical.com>,
        "Guilherme G. Piccoli" <kernel@...ccoli.net>
Subject: Re: [PATCH] hugetlb: Add nohugepages parameter to prevent hugepages
 creation

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.
-- 
Michal Hocko
SUSE Labs