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

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Message-ID: <20191015121803.GB24932@dhcp22.suse.cz>
Date:   Tue, 15 Oct 2019 14:18:03 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Guilherme Piccoli <gpiccoli@...onical.com>
Cc:     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 Fri 11-10-19 21:41:01, Guilherme Piccoli wrote:
> On Fri, Oct 11, 2019 at 8:52 PM Qian Cai <cai@....pw> wrote:
> >
> >
> > It simply error-prone to reuse the sysctl.conf from the first kernel, as it could contains lots of things that will kill kdump kernel.
> 
> Makes sense, I agree with you. But still, there's no
> formal/right/single way to do kdump, so I don't think we should rely
> on "rootfs kdump is wrong" to refuse this patch's idea. If so, we
> should then formalize the right way of kdumping.
> Of course, this is only my opinion, let's see what people think about it!

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.
-- 
Michal Hocko
SUSE Labs