linux-kernel - Re: [PATCH mm-new v3 1/1] mm/khugepaged: abort collapse scan on non-swap entries

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <3b6f0c03-9f1b-4213-8364-be4c84723803@lucifer.local>
Date: Tue, 14 Oct 2025 15:43:24 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Lance Yang <lance.yang@...ux.dev>
Cc: David Hildenbrand <david@...hat.com>, akpm@...ux-foundation.org,
        Liam.Howlett@...cle.com, baohua@...nel.org,
        baolin.wang@...ux.alibaba.com, dev.jain@....com, hughd@...gle.com,
        ioworker0@...il.com, kirill@...temov.name,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org, mpenttil@...hat.com,
        npache@...hat.com, ryan.roberts@....com, ziy@...dia.com,
        richard.weiyang@...il.com
Subject: Re: [PATCH mm-new v3 1/1] mm/khugepaged: abort collapse scan on
 non-swap entries

On Tue, Oct 14, 2025 at 10:37:28PM +0800, Lance Yang wrote:
>
>
> On 2025/10/14 22:32, David Hildenbrand wrote:
> >
> > > static inline int pte_protnone(pte_t pte)
> > > {
> > >     return (pte_flags(pte) & (_PAGE_PROTNONE | _PAGE_PRESENT))
> > >         == _PAGE_PROTNONE;
> > > }
> > >
> > > static inline int pte_present(pte_t a)
> > > {
> > >     return pte_flags(a) & (_PAGE_PRESENT | _PAGE_PROTNONE);
> > > }
> > > ```
> > >
> > > On x86, pte_present() returns true for a protnone pte. And I'd assume
> > > other archs behave similarly ...
> >
> > Applies to all architecture. prot-none entries must be present,
> > otherwise we'd have a lot of other issues :)
>
> Thanks for confirming, David! That's good to know ;p
>
> So @Lorenzo, looks like we're good here on the protnone front. Does
> that clear up your concern?
>

No absolutely not, I go into detail as to why in my reply. I don't want
that upstreamed.