linux-kernel - Re: [PATCH v2 0/3] Randomize free memory

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Message-ID: <20181018134402.GE18839@dhcp22.suse.cz>
Date:   Thu, 18 Oct 2018 15:44:02 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Kees Cook <keescook@...omium.org>,
        Linux MM <linux-mm@...ck.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 0/3] Randomize free memory

On Thu 11-10-18 11:03:07, Dan Williams wrote:
> On Thu, Oct 11, 2018 at 4:56 AM Michal Hocko <mhocko@...nel.org> wrote:
[...]
> > In any case, I believe the change itself is not controversial as long it
> > is opt-in (potentially autotuned based on specific HW)
> 
> Do you mean disable shuffling on systems that don't have a
> memory-side-cache unless / until we can devise a security benefit
> curve relative to shuffle-order? The former I can do, the latter, I'm
> at a loss.

Yes, enable when the HW requires that for whatever reason and make add a
global knob to enable it for those that might find it useful for
security reasons with a clear cost/benefit description. Not "this is tha
security thingy enable and feel safe(r)"
-- 
Michal Hocko
SUSE Labs