linux-kernel - Re: RFC v2: post-init-read-only protection for data allocated dynamically

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Date:   Thu, 4 May 2017 07:30:59 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Igor Stoppa <igor.stoppa@...wei.com>,
        Michal Hocko <mhocko@...nel.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: RFC v2: post-init-read-only protection for data allocated
 dynamically

On 05/04/2017 01:17 AM, Igor Stoppa wrote:
> Or, let me put it differently: my goal is to not fracture more pages
> than needed.
> It will probably require some profiling to figure out what is the
> ballpark of the memory footprint.

This is easy to say, but hard to do.  What if someone loads a different
set of LSMs, or uses a very different configuration?  How could this
possibly work generally without vastly over-reserving in most cases?

> I might have overlooked some aspect of this, but the overall goal
> is to have a memory range (I won't call it zone, to avoid referring to a
> specific implementation) which is as tightly packed as possible, stuffed
> with all the data that is expected to become read-only.

I'm starting with the assumption that a new zone isn't feasible. :)