[LSF/MM/BPF TOPIC] mshare - sharing page tables across processes

[LSF/MM/BPF TOPIC] mshare - sharing page tables across processes

[anthony.yznaga]

mshare is a new form of shared memory that shares resources between 
processes, namely the page tables entries and VMAs of the shared 
objects. Advantages include reduced memory consumption through 
eliminating the need for duplicated PTEs in each process, reduced 
overhead needed to fault shared pages into multiple processes, and the 
ability for updates to the memory such as protection changes to be 
immdediately visible to all sharing processes.

For some time now the proposed API has continued to evolve. With 
feedback from mm maintainers, a new approach using syscalls is being 
taken to create, attach, and deattach mshare regions and to map and 
manipulate the memory objects within a region.

Let's discuss the current state of the API and technical challenges of 
managing and accomodating shared page tables in the kernel.

Anthony


References:

https://lore.kernel.org/linux-mm/20250820010415.699353-1-anthony.yznaga@oracle.com/
https://lore.kernel.org/linux-mm/20250404021902.48863-1-anthony.yznaga@oracle.com/

Re: [LSF/MM/BPF TOPIC] mshare - sharing page tables across processes

[Kalesh Singh]

On Mon, Feb 23, 2026 at 6:12 PM <anthony.yznaga@oracle.com> wrote:
>
> mshare is a new form of shared memory that shares resources between
> processes, namely the page tables entries and VMAs of the shared
> objects. Advantages include reduced memory consumption through
> eliminating the need for duplicated PTEs in each process, reduced
> overhead needed to fault shared pages into multiple processes, and the
> ability for updates to the memory such as protection changes to be
> immdediately visible to all sharing processes.
>
> For some time now the proposed API has continued to evolve. With
> feedback from mm maintainers, a new approach using syscalls is being
> taken to create, attach, and deattach mshare regions and to map and
> manipulate the memory objects within a region.
>
> Let's discuss the current state of the API and technical challenges of
> managing and accomodating shared page tables in the kernel.
>
> Anthony
>
>
> References:
>
> https://lore.kernel.org/linux-mm/20250820010415.699353-1-anthony.yznaga@oracle.com/
> https://lore.kernel.org/linux-mm/20250404021902.48863-1-anthony.yznaga@oracle.com/

Hi Anthony,

I would be very interested in participating in this discussion at LSF/MM.

As mentioned on the mailing list, we are currently exploring similar
optimizations to deduplicate page tables for Android's Zygote process.
I'd love to join the session to discuss how the proposed sharing
mechanisms might align.

Thanks,
Kalesh

>
>

Re: [LSF/MM/BPF TOPIC] mshare - sharing page tables across processes

[Isaac Manjarres]

On Wed, Feb 25, 2026 at 04:59:32PM -0800, Kalesh Singh wrote:
> On Mon, Feb 23, 2026 at 6:12 PM <anthony.yznaga@oracle.com> wrote:
> >
> > mshare is a new form of shared memory that shares resources between
> > processes, namely the page tables entries and VMAs of the shared
> > objects. Advantages include reduced memory consumption through
> > eliminating the need for duplicated PTEs in each process, reduced
> > overhead needed to fault shared pages into multiple processes, and the
> > ability for updates to the memory such as protection changes to be
> > immdediately visible to all sharing processes.
> >
> > For some time now the proposed API has continued to evolve. With
> > feedback from mm maintainers, a new approach using syscalls is being
> > taken to create, attach, and deattach mshare regions and to map and
> > manipulate the memory objects within a region.
> >
> > Let's discuss the current state of the API and technical challenges of
> > managing and accomodating shared page tables in the kernel.
> >
> > Anthony
> >
> >
> > References:
> >
> > https://lore.kernel.org/linux-mm/20250820010415.699353-1-anthony.yznaga@oracle.com/
> > https://lore.kernel.org/linux-mm/20250404021902.48863-1-anthony.yznaga@oracle.com/
> 
> Hi Anthony,
> 
> I would be very interested in participating in this discussion at LSF/MM.
> 
> As mentioned on the mailing list, we are currently exploring similar
> optimizations to deduplicate page tables for Android's Zygote process.
> I'd love to join the session to discuss how the proposed sharing
> mechanisms might align.
> 
> Thanks,
> Kalesh

Hello Anthony,

I'm also working on optimizing pagetable usage in Android with Kalesh,
so I'm definitely interested in participating in this discussion as
well.

Thanks,
Isaac