Re: [RESEND PATCH] mm/sparsemem: use wrapped macros instead of open-coding

[chenqiwu <qiwuchen55@gmail.com>]

On Tue, Mar 10, 2020 at 07:10:10PM -0700, John Hubbard wrote:
> On 3/6/20 2:19 AM, qiwuchen55@gmail.com wrote:
> > From: chenqiwu <chenqiwu@xiaomi.com>
> > 
> > Use wrapped macros instead of open-coding for better code
> > readability.
> > 
> > Signed-off-by: chenqiwu <chenqiwu@xiaomi.com>
> 
> 
> This breaks my x86 (64-bit) build:
> 
> mm/sparse.c: In function ‘check_usemap_section_nr’:
> mm/sparse.c:389:33: error: implicit declaration of function ‘virt_to_pfn’; did you mean ‘virt_to_phys’? [-Werror=implicit-function-declaration]
>   389 |  usemap_snr = pfn_to_section_nr(virt_to_pfn(usage));
>       |                                 ^~~~~~~~~~~
>       |                                 virt_to_phys
> 
> 
> ...and I think the reason is that the arch/x86/include/asm/page.h does not
> have virt_to_pfn(). For that reason, I'm concerned that the following fix, 
> which fixes up x86, may not completely correct for the patch.
> 
> Here's a compile-tested (only, and only on x86 64-bit) fix:
> 
> diff --git a/arch/x86/include/asm/page.h b/arch/x86/include/asm/page.h
> index 7555b48803a8..982bc76bf13c 100644
> --- a/arch/x86/include/asm/page.h
> +++ b/arch/x86/include/asm/page.h
> @@ -62,6 +62,9 @@ static inline void copy_user_page(void *to, void *from, unsigned long vaddr,
>  #define __boot_va(x)		__va(x)
>  #define __boot_pa(x)		__pa(x)
>  
> +#define virt_to_pfn(kaddr)	(__pa(kaddr) >> PAGE_SHIFT)
> +#define pfn_to_virt(pfn)	__va((pfn) << PAGE_SHIFT)
> +
>  /*
>   * virt_to_page(kaddr) returns a valid pointer if and only if
>   * virt_addr_valid(kaddr) returns true.
> 
> 
> thanks,
> -- 
> John Hubbard
> NVIDIA

Hi John,
I tested this patch only on arm64 build, not sure if any other build
breakings. But I think any architecture is worth to support virt_to_pfn()
API. Could you please send your compile-tested patch to x86 upstream?

Thanks
Qiwu