[PATCH] powerpc: Use printk instead of WARN in change_memory_attr

[Christophe Leroy]

Le 27/08/2024 à 11:12, Ritesh Harjani (IBM) a écrit :
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> 
> Use pr_warn_once instead of WARN_ON_ONCE as discussed here [1]
> for printing possible use of set_memory_* on linear map on Hash.
> 
> [1]: https://lore.kernel.org/all/877cc2fpi2.fsf@mail.lhotse/#t
> 
> Signed-off-by: Ritesh Harjani (IBM) <ritesh.list at gmail.com>
> ---
>   arch/powerpc/mm/pageattr.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/mm/pageattr.c b/arch/powerpc/mm/pageattr.c
> index ac22bf28086f..c8c2d664c6f3 100644
> --- a/arch/powerpc/mm/pageattr.c
> +++ b/arch/powerpc/mm/pageattr.c
> @@ -94,8 +94,11 @@ int change_memory_attr(unsigned long addr, int numpages, long action)
>          if (!radix_enabled()) {
>                  int region = get_region_id(addr);
> 
> -               if (WARN_ON_ONCE(region != VMALLOC_REGION_ID && region != IO_REGION_ID))
> +               if (region != VMALLOC_REGION_ID && region != IO_REGION_ID) {
> +                       pr_warn_once("%s: possible use of set_memory_* on linear map on Hash from (%ps)\n",
> +                                       __func__, __builtin_return_address(0));

Is it really only linear map ?

What about "possible user of set_memory_* outside of vmalloc or io region.

Maybe a show_stack() would also be worth it ?


But in principle I think it would be better to keep the WARN_ONCE until 
we can add __must_check to set_memory_xxx() functions to be sure all 
callers check the result, as mandated by 
https://github.com/KSPP/linux/issues/7

Christophe