linux-kernel - Re: [PATCH RFC 00/11] mm: ASI integration for the page allocator

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] [day] [month] [year] [list]

Message-ID: <DAJ0LUX8F2IW.Q95PTFBNMFOI@google.com>
Date: Tue, 10 Jun 2025 17:04:46 +0000
From: Brendan Jackman <jackmanb@...gle.com>
To: Brendan Jackman <jackmanb@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, 
	Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>, 
	Dave Hansen <dave.hansen@...ux.intel.com>, <x86@...nel.org>, 
	Andrew Morton <akpm@...ux-foundation.org>, David Rientjes <rientjes@...gle.com>, 
	Vlastimil Babka <vbabka@...e.cz>, David Hildenbrand <david@...hat.com>
Cc: <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>, 
	Mike Rapoport <rppt@...nel.org>, Junaid Shahid <junaids@...gle.com>, 
	Reiji Watanabe <reijiw@...gle.com>, Patrick Bellasi <derkling@...gle.com>, 
	Yosry Ahmed <yosry.ahmed@...ux.dev>
Subject: Re: [PATCH RFC 00/11] mm: ASI integration for the page allocator

On Thu Mar 13, 2025 at 6:11 PM UTC, Brendan Jackman wrote:
> .:: Patchset overview

Hey all, I have been down the pagetable mines lately trying to figure
out a solution to the page cache issue (the 70% FIO degradatation [0]).
I've got a prototype based on the idea I discussed at LSF/MM/BPF
that's slowly coming together. My hope is that as soon as I can
convincingly claim with a straight face that I know how to solve that
problem, I can transition from <post an RFC every N months then
disappear> mode into being a bit more visible with development
iterations...

[0] https://lore.kernel.org/linux-mm/20250129144320.2675822-1-jackmanb@google.com/

In the meantime, I am still provisionally planning to make the topic
of this RFC the first [PATCH] series for ASI. Obviously before I can
seriously ask Andrew to merge I'll also need to establish some
consensus on the x86 side, but in the meantime I think we're getting
close enough to start discussing the mm code.

So.. does anyone have a bit of time to look over this and see if the
implementation makes sense? Is the basic idea on the right lines?
Also if there's anything I can do to make that easier (is it worth
rebasing?) let me know.

Also, I guess I should also note my aspirational plan for the next few
months, it goes...

1. Get a convincing PoC working that improves the FIO degradation.

2. Gather it into a fairly messy but at least surveyable branch and push
   that to Github or whatever.

3. Show that to x86 folks and hopefully (!!) get some maintainers to
   give a nod like "yep we want ASI and we're more or less sold that
   the developers know how to make it performant".

4. Turn this [RFC] into a [PATCH]. So start by trying to merge the stuff
   that manages the restricted address space, leaving the logic of actually
   _using_ it for a later series.

5. [Maybe this can be partially paralellised with 4] start a new [PATCH]
   series that starts adding in the x86 stuff to actually switch address
   spaces etc. Basically this means respinning the patches that Boris
   has reviewed in [1]. Since we already have the page_alloc stuff, it
   should be possible to start testing this code end-to-end quickly.

[1] https://lore.kernel.org/linux-mm/20250110-asi-rfc-v2-v2-0-8419288bc805@google.com/

Anyone have any thoughts on that overall strategy?

Cheers,
Brendan