Subject: Re: linux-next: build failure after merge of the akpm-current tree

From: Randy Dunlap <[email-masked]>
Date: Fri, 15 Nov 2019 15:37:30 -0800

On 11/15/19 3:23 PM, Andrew Morton wrote:
> On Fri, 15 Nov 2019 18:19:57 +1100 Stephen Rothwell <[email-masked]> wrote:
> 
>> Hi all,
>>
>> [Also reported by Randy Dunlap]
>>
>> After merging the akpm-current tree, today's linux-next build (arm
>> multi_v7_defconfig) failed like this:
>>
>> mm/vmalloc.c: In function '__purge_vmap_area_lazy':
>> mm/vmalloc.c:1286:8: error: 'SHARED_KERNEL_PMD' undeclared (first use in this function)
>>  1286 |   if (!SHARED_KERNEL_PMD && boot_cpu_has(X86_FEATURE_PTI))
>>       |        ^~~~~~~~~~~~~~~~~
>> mm/vmalloc.c:1286:8: note: each undeclared identifier is reported only once for each function it appears in
>> mm/vmalloc.c:1286:29: error: implicit declaration of function 'boot_cpu_has' [-Werror=implicit-function-declaration]
>>  1286 |   if (!SHARED_KERNEL_PMD && boot_cpu_has(X86_FEATURE_PTI))
>>       |                             ^~~~~~~~~~~~
>> mm/vmalloc.c:1286:42: error: 'X86_FEATURE_PTI' undeclared (first use in this function)
>>  1286 |   if (!SHARED_KERNEL_PMD && boot_cpu_has(X86_FEATURE_PTI))
>>       |                                          ^~~~~~~~~~~~~~~
>>
>> Caused by commit
>>
>>   07ef40e149bf ("mm-vmalloc-fix-regression-caused-by-needless-vmalloc_sync_all-fix")
>>
>> SHARED_KERNEL_PMD, boot_cpu_has() and X86_FEATURE_PTI are only defined
>> for X86.
>>
>> I have reverted that commit for today.
> 
> Thanks.  So it has to be an ifdef.

Yes, that works.  Thanks.

Acked-by: Randy Dunlap <[email-masked]> # build-tested

> --- a/mm/vmalloc.c~mm-vmalloc-fix-regression-caused-by-needless-vmalloc_sync_all-fix-fix
> +++ a/mm/vmalloc.c
> @@ -1255,17 +1255,17 @@ static bool __purge_vmap_area_lazy(unsig
>  	if (unlikely(valist == NULL))
>  		return false;
>  
> -	if (IS_ENABLED(CONFIG_X86_PAE)) {
> -		/*
> -		 * First make sure the mappings are removed from all page-tables
> -		 * before they are freed.
> -		 *
> -		 * This is only needed on x86-32 with !SHARED_KERNEL_PMD, which
> -		 * is the case on a PAE kernel with PTI enabled.
> -		 */
> -		if (!SHARED_KERNEL_PMD && boot_cpu_has(X86_FEATURE_PTI))
> -			vmalloc_sync_all();
> -	}
> +#ifdef CONFIG_X86_PAE
> +	/*
> +	 * First make sure the mappings are removed from all pagetables before
> +	 * they are freed.
> +	 *
> +	 * This is only needed on x86-32 with !SHARED_KERNEL_PMD, which is the
> +	 * case on a PAE kernel with PTI enabled.
> +	 */
> +	if (!SHARED_KERNEL_PMD && boot_cpu_has(X86_FEATURE_PTI))
> +		vmalloc_sync_all();
> +#endif
>  
>  	/*
>  	 * TODO: to calculate a flush range without looping.
> _
> 

-- 
~Randy
Reported-by: Randy Dunlap <[email-masked]>