linux-kernel - Re: [PATCH v5 0/8] Fix stale IOTLB entries for kernel address space

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Message-ID: <abe539bb-375a-43ec-ba36-6d10a35dd85d@redhat.com>
Date: Thu, 9 Oct 2025 21:16:34 +0200
From: David Hildenbrand <david@...hat.com>
To: Dave Hansen <dave.hansen@...el.com>, Lu Baolu <baolu.lu@...ux.intel.com>,
 Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
 Robin Murphy <robin.murphy@....com>, Kevin Tian <kevin.tian@...el.com>,
 Jason Gunthorpe <jgg@...dia.com>, Jann Horn <jannh@...gle.com>,
 Vasant Hegde <vasant.hegde@....com>, Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
 Alistair Popple <apopple@...dia.com>, Peter Zijlstra <peterz@...radead.org>,
 Uladzislau Rezki <urezki@...il.com>,
 Jean-Philippe Brucker <jean-philippe@...aro.org>,
 Andy Lutomirski <luto@...nel.org>, Yi Lai <yi1.lai@...el.com>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>,
 Andrew Morton <akpm@...ux-foundation.org>, Vlastimil Babka <vbabka@...e.cz>,
 Mike Rapoport <rppt@...nel.org>, Michal Hocko <mhocko@...nel.org>,
 Matthew Wilcox <willy@...radead.org>
Cc: iommu@...ts.linux.dev, security@...nel.org, x86@...nel.org,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 0/8] Fix stale IOTLB entries for kernel address space

On 08.10.25 21:42, Dave Hansen wrote:
> I wondered why no mm folks were commenting on this. linux-mm@ was cc'd,
> but the _people_ on cc seem to have been almost all IOMMU and x86 folks.
> so I added a few mm folks...

Thanks. Lately I find myself scanning linux-mm only randomly. So if it's 
not in my inbox, likely I won't realize easily that there is something 
that needs our attention.

Will take a look.

> 
> On 9/25/25 13:24, Dave Hansen wrote:
>> On 9/18/25 22:39, Lu Baolu wrote:
>>> This solution introduces a deferred freeing mechanism for kernel page
>>> table pages, which provides a safe window to notify the IOMMU to
>>> invalidate its caches before the page is reused.
>>
>> I think all the activity has died down and I everyone seems happy enough
>> with how this looks. Right?
>>
>> So is this something we should prod Andrew to take through the mm tree,
>> or is it x86-specific enough it should go through tip?
> 
> Hi Folks! We've got a bug fix here that has impact on x86, mm, and IOMMU
> code. I know I've talked with a few of you about this along the way, but
> it's really thin on mm reviews, probably because mm folks haven't been
> cc'd. Any eyeballs on it would be appreciated!
> 
> It seems like it should _probably_ go through the mm tree, although I'm
> happy to send it through tip if folks disagree.
> 
> Diffstat for reference:
> 
>   arch/x86/Kconfig              |  1 +
>   arch/x86/mm/init_64.c         |  2 +-
>   arch/x86/mm/pat/set_memory.c  |  2 +-
>   arch/x86/mm/pgtable.c         | 12 ++++-----
>   drivers/iommu/iommu-sva.c     | 29 +++++++++++++++++++++-
>   include/asm-generic/pgalloc.h | 18 ++++++++++++++
>   include/linux/iommu.h         |  4 +++
>   include/linux/mm.h            | 24 +++++++++++++++---
>   include/linux/page-flags.h    | 46 +++++++++++++++++++++++++++++++++++
>   mm/Kconfig                    |  3 +++
>   mm/pgtable-generic.c          | 39 +++++++++++++++++++++++++++++
>   11 files changed, 168 insertions(+), 12 deletions(-)
> 

-- 
Cheers

David / dhildenb