Re: [PATCH 0/4] initial work on making VMA flags a bitmap

[Alice Ryhl <aliceryhl@google.com>]

On Thu, Oct 30, 2025 at 08:33:10AM +0000, Lorenzo Stoakes wrote:
> +cc Alice - could you help look at this? It seems I have broken the rust
> bindings here :)
> 
> Thanks!
> 
> On Wed, Oct 29, 2025 at 09:07:07PM -0600, Nico Pache wrote:
> > Hey Lorenzo,
> >
> > I put your patchset into the Fedora Koji system to run some CI on it for you.
> >
> > It failed to build due to what looks like some Rust bindings.
> >
> > Heres the build: https://koji.fedoraproject.org/koji/taskinfo?taskID=138547842
> >
> > And x86 build logs:
> > https://kojipkgs.fedoraproject.org//work/tasks/7966/138547966/build.log
> >
> > The error is pretty large but here's a snippet if you want an idea
> >
> > error[E0425]: cannot find value `VM_READ` in crate `bindings`
> >    --> rust/kernel/mm/virt.rs:399:44
> >     |
> > 399 |     pub const READ: vm_flags_t = bindings::VM_READ as vm_flags_t;
> >     |                                            ^^^^^^^ not found in `bindings`
> > error[E0425]: cannot find value `VM_WRITE` in crate `bindings`
> >    --> rust/kernel/mm/virt.rs:402:45
> >     |
> > 402 |     pub const WRITE: vm_flags_t = bindings::VM_WRITE as vm_flags_t;
> >     |                                             ^^^^^^^^ not found
> > in `bindings`
> > error[E0425]: cannot find value `VM_EXEC` in crate `bindings`
> >      --> rust/kernel/mm/virt.rs:405:44
> >       |
> >   405 |     pub const EXEC: vm_flags_t = bindings::VM_EXEC as vm_flags_t;
> >       |                                            ^^^^^^^ help: a
> > constant with a similar name exists: `ET_EXEC`
> >       |
> >      ::: /builddir/build/BUILD/kernel-6.18.0-build/kernel-6.18-rc3-16-ge53642b87a4f/linux-6.18.0-0.rc3.e53642b87a4f.31.bitvma.fc44.x86_64/rust/bindings/bindings_generated.rs:13881:1
> >       |
> > 13881 | pub const ET_EXEC: u32 = 2;
> >       | ---------------------- similarly named constant `ET_EXEC` defined here
> > error[E0425]: cannot find value `VM_SHARED` in crate `bindings`
> >    --> rust/kernel/mm/virt.rs:408:46
> >     |
> > 408 |     pub const SHARED: vm_flags_t = bindings::VM_SHARED as vm_flags_t;
> >     |                                              ^^^^^^^^^ not found
> > in `bindings`
> >
> > In the next version Ill do the same and continue with the CI testing for you!
> 
> Thanks much appreciated :)
> 
> It seems I broke the rust bindings (clearly), have pinged Alice to have a
> look!
> 
> May try and repro my side to see if there's something trivial that I could
> take a look at.
> 
> I ran this through mm self tests, allmodconfig + a bunch of other checks
> but ofc enabling rust was not one, I should probably update my scripts [0]
> to do that too :)
> 
> Cheers, Lorenzo
> 
> [0]:https://github.com/lorenzo-stoakes/review-scripts

I can help convert the Rust bindings to work with this approach. I see
there is a nice and simple vma_test() method for checking a flag, but I
don't see any equivalent method for setting or unsetting a given bit.
What would be the best function for Rust to call to set or unset a given
bit in the vma flags?

Alice