linux-kernel - Re: [RFC PATCH 0/6] Add support for shared PTEs across processes

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Date:   Tue, 25 Jan 2022 17:01:16 +0300
From:   "Kirill A. Shutemov" <kirill@...temov.name>
To:     David Hildenbrand <david@...hat.com>
Cc:     William Kucharski <kucharsk@...il.com>,
        Khalid Aziz <khalid.aziz@...cle.com>,
        akpm@...ux-foundation.org, willy@...radead.org,
        longpeng2@...wei.com, arnd@...db.de, dave.hansen@...ux.intel.com,
        rppt@...nel.org, surenb@...gle.com, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [RFC PATCH 0/6] Add support for shared PTEs across processes

On Tue, Jan 25, 2022 at 02:18:57PM +0100, David Hildenbrand wrote:
> On 25.01.22 13:09, William Kucharski wrote:
> > I would think this should be the case; certainly it seems to be a more effective approach than having to manually enable sharing via the API in every case or via changes to ld.so.
> > 
> > If anything it might be useful to have an API for shutting it off, though there are already multiple areas where the system shares resources in ways that cannot be shut off by user action.
> > 
> 
> I don't have time to look into details right now, but I see various
> possible hard-to-handle issues with sharing anon pages via this
> mechanism between processes.

Right. We should not break invariant that an anonymous page can only be
mapped into a process once. Otherwise may need to deal with new class of
security issues.

-- 
 Kirill A. Shutemov