Re: rust compile failure in next-20260730

[Thorsten Leemhuis]

On 7/31/26 14:28, Bert Karwatzki wrote:
> With next-20260730 building a kernel with CONFIG_RUST=y fails with
> the following error:

Ran into this, too. Fixing this is discussed in this thread:
https://lore.kernel.org/all/20260731075644.20215-1-ojeda@xxxxxxxxxx/

>  RUSTC L rust/kernel.o
> error[E0308]: mismatched types
>      --> rust/kernel/sync/poll.rs:175:44
>       |
>   175 |         unsafe { bindings::kvfree_call_rcu((*ptr).rcu.get(), ptr.cast::<ffi::c_void>()) };
>       |                  ------------------------- ^^^^^^^^^^^^^^^^ expected `*mut kvfree_rcu_head`, found `*mut callback_head`
>       |                  |
>       |                  arguments to this function are incorrect
>       |
>       = note: expected raw pointer `*mut bindings::kvfree_rcu_head`
>                  found raw pointer `*mut bindings::callback_head`
> note: function defined here
>      --> /mnt/data/linux-forest/linux-next/rust/bindings/bindings_generated.rs:73708:12
>       |
> 73708 |     pub fn kvfree_call_rcu(head: *mut kvfree_rcu_head, ptr: *mut ffi::c_void);
>       |            ^^^^^^^^^^^^^^^
> 
> error: aborting due to 1 previous error
> 
> For more information about this error, try `rustc --explain E0308`.
> make[5]: *** [rust/Makefile:781: rust/kernel.o] Fehler 1
> make[4]: *** [Makefile:1420: prepare] Fehler 2
> make[3]: *** [debian/rules:80: build-arch] Fehler 2
> 
> Reverting the following commits:
> ef32a74f8f6a ("mm/slab: introduce kfree_rcu_nolock()")
> bdd0cc9f0ffc ("mm/slab: introduce struct kvfree_rcu_head for kvfree_rcu batching")
>     
> make the compilation work again.   
> 
> Bert Karwatzki