Re: [akpm-mm:mm-unstable 113/133] error[E0277]: `*const kernel::bindings::vm_uffd_ops` cannot be shared between threads safely

[Alice Ryhl <aliceryhl@google.com>]

On Tue, Apr 7, 2026 at 11:59 PM Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Tue, 07 Apr 2026 15:58:09 +0800 kernel test robot <lkp@intel.com> wrote:
>
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable
> > head:   3fa44141e0bbd5062f2ef0c5cdddd98275d3223e
> > commit: 694fc0bd3ca5420f4e1105d2dec02327cfc5d64b [113/133] userfaultfd: introduce vm_uffd_ops
> > config: x86_64-randconfig-074-20260407 (https://download.01.org/0day-ci/archive/20260407/202604071509.y5vLetYd-lkp@intel.com/config)
> > compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
> > rustc: rustc 1.88.0 (6b00bc388 2025-06-23)
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260407/202604071509.y5vLetYd-lkp@intel.com/reproduce)
> >
> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> > the same patch/commit), kindly add following tags
> > | Reported-by: kernel test robot <lkp@intel.com>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202604071509.y5vLetYd-lkp@intel.com/
>
> Various forms of "userfaultfd: introduce vm_uffd_ops" have been in
> mm.git since March 6.  Thanks (much), but is it possible to get more
> timely notifications?
>
> > All errors (new ones prefixed by >>):
> >
> > >> error[E0277]: `*const kernel::bindings::vm_uffd_ops` cannot be shared between threads safely
> >    --> drivers/android/binder/page_range.rs:146:23
> >    |
> >    146   | static BINDER_VM_OPS: bindings::vm_operations_struct = pin_init::zeroed();
> >    |                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `*const kernel::bindings::vm_uffd_ops` cannot be shared between threads safely
> >    |
> >    = help: within `kernel::bindings::vm_operations_struct`, the trait `Sync` is not implemented for `*const kernel::bindings::vm_uffd_ops`
> >    note: required because it appears within the type `kernel::bindings::vm_operations_struct`
> >    --> rust/bindings/bindings_generated.rs:74703:12
> >    |
> >    74703 | pub struct vm_operations_struct {
> >    |            ^^^^^^^^^^^^^^^^^^^^
> >    = note: shared static variables must have a type that implements `Sync`
>
> We've seen this one before.  Sorry, I'm (still) not set up for
> build-testing rusty things and I suspect I'm not the only one.
>
> Alice, Miguel: please can you help us here?

Hi Andrew,

I introduced this bug in commit 8ef2c15aeae0 ("rust_binder: check
ownership before using vma") and fixed it again in commit ec327abae5ed
("rust_binder: use AssertSync for BINDER_VM_OPS"). This means that the
bug is present from v7.0-rc4 and was fixed as of v7.0-rc7. To avoid
this build failure, the "userfaultfd: introduce vm_uffd_ops" commit
must either be on top of v7.0-rc7, or it must be on a base that does
not include v7.0-rc4.

Alice