linux-kernel - Re: [PATCH v2 0/2] mm,fork,security: introduce MADV

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Message-ID: <20170810130645.GT23863@dhcp22.suse.cz>
Date:   Thu, 10 Aug 2017 15:06:45 +0200
From:   Michal Hocko <mhocko@...nel.org>
To:     Florian Weimer <fweimer@...hat.com>
Cc:     riel@...hat.com, linux-kernel@...r.kernel.org,
        mike.kravetz@...cle.com, linux-mm@...ck.org, colm@...costs.net,
        akpm@...ux-foundation.org, keescook@...omium.org,
        luto@...capital.net, wad@...omium.org, mingo@...nel.org,
        kirill@...temov.name, dave.hansen@...el.com,
        linux-api@...r.kernel.org
Subject: Re: [PATCH v2 0/2] mm,fork,security: introduce MADV_WIPEONFORK

On Mon 07-08-17 16:19:18, Florian Weimer wrote:
> On 08/07/2017 03:46 PM, Michal Hocko wrote:
> > How do they know that they need to regenerate if they do not get SEGV?
> > Are they going to assume that a read of zeros is a "must init again"? Isn't
> > that too fragile?
> 
> Why would it be fragile?  Some level of synchronization is needed to set
> things up, of course, but I think it's possible to write a lock-free
> algorithm to maintain the state even without strong guarantees of memory
> ordering from fork.

Yeah, that is what I meant as fragile... I am not question this is
impossible.
-- 
Michal Hocko
SUSE Labs