Re: [linus:master] [atomic] 80047d84ee: WARNING:at_include/linux/instrumented.h:#__split_huge_pmd_locked

[Andrew Morton]

On Tue, 3 Nov 2026 13:26:47 +0100 Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> AFAICT this is pxx_xchg64() from the PAE code operating on an on-stack
> pmd value.
> 
> The below 'fixes' it, but the question is of course, WTF are we using an
> on-stack pmd value for set_pmd().
> 
> --- a/arch/x86/include/asm/pgtable-3level_types.h
> +++ b/arch/x86/include/asm/pgtable-3level_types.h
> @@ -5,12 +5,12 @@
>  #ifndef __ASSEMBLER__
>  #include <linux/types.h>
>  
> -typedef u64	pteval_t;
> -typedef u64	pmdval_t;
> -typedef u64	pudval_t;
> -typedef u64	p4dval_t;
> -typedef u64	pgdval_t;
> -typedef u64	pgprotval_t;
> +typedef u64 __aligned(8)	pteval_t;
> +typedef u64 __aligned(8)	pmdval_t;
> +typedef u64 __aligned(8)	pudval_t;
> +typedef u64 __aligned(8)	p4dval_t;
> +typedef u64 __aligned(8)	pgdval_t;
> +typedef u64 __aligned(8)	pgprotval_t;
>  

(cc Dave)

fwiw this was discussed a couple of years ago but nothing really came
of it.

https://lore.kernel.org/20240401185451.6897208962d3fc47a12ffb5a@xxxxxxxx