Re: [RFC v2 2/3] atomic: Specify alignment for atomic_t and atomic64_t

[Finn Thain <fthain@linux-m68k.org>]

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On Mon, 22 Sep 2025, Geert Uytterhoeven wrote:

> 
> This triggers a failure in kernel/bpf/rqspinlock.c:
> 
> kernel/bpf/rqspinlock.c: In function ‘bpf_res_spin_lock’:
> include/linux/compiler_types.h:572:45: error: call to
> ‘__compiletime_assert_397’ declared with attribute error: BUILD_BUG_ON
> failed: __alignof__(rqspinlock_t) != __alignof__(struct
> bpf_res_spin_lock)
>   572 |         _compiletime_assert(condition, msg,
> __compiletime_assert_, __COUNTER__)
>       |                                             ^
> include/linux/compiler_types.h:553:25: note: in definition of macro
> ‘__compiletime_assert’
>   553 |                         prefix ## suffix();
>          \
>       |                         ^~~~~~
> include/linux/compiler_types.h:572:9: note: in expansion of macro
> ‘_compiletime_assert’
>   572 |         _compiletime_assert(condition, msg,
> __compiletime_assert_, __COUNTER__)
>       |         ^~~~~~~~~~~~~~~~~~~
> include/linux/build_bug.h:39:37: note: in expansion of macro
> ‘compiletime_assert’
>    39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
>       |                                     ^~~~~~~~~~~~~~~~~~
> include/linux/build_bug.h:50:9: note: in expansion of macro ‘BUILD_BUG_ON_MSG’
>    50 |         BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
>       |         ^~~~~~~~~~~~~~~~
> kernel/bpf/rqspinlock.c:695:9: note: in expansion of macro ‘BUILD_BUG_ON’
>   695 |         BUILD_BUG_ON(__alignof__(rqspinlock_t) !=
> __alignof__(struct bpf_res_spin_lock));
>       |         ^~~~~~~~~~~~
> 
> I haven't investigated it yet.
> 

Yes, I noticed that also, after I started building with defconfigs.
I pushed a new patch to my github repo.

https://github.com/fthain/linux/tree/atomic_t