Re: [Xen-devel] [RFC PATCH v1 01/33] mm: introduce common help functions to deal with reserved/managed pages

[Sam Ravnborg <sam@xxxxxxxxxxxx>]

On Tue, Mar 05, 2013 at 10:54:44PM +0800, Jiang Liu wrote:
> Code to deal with reserved/managed pages are duplicated by many
> architectures, so introduce common help functions to reduce duplicated
> code. These common help functions will also be used to concentrate code
> to modify totalram_pages and zone->managed_pages, which makes the code
> much more clear.
> 
> Signed-off-by: Jiang Liu <jiang.liu@xxxxxxxxxx>
> ---
>  include/linux/mm.h |   37 +++++++++++++++++++++++++++++++++++++
>  mm/page_alloc.c    |   20 ++++++++++++++++++++
>  2 files changed, 57 insertions(+)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 7acc9dc..881461c 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1295,6 +1295,43 @@ extern void free_area_init_node(int nid, unsigned long 
> * zones_size,
>               unsigned long zone_start_pfn, unsigned long *zholes_size);
>  extern void free_initmem(void);
>  
> +/* Help functions to deal with reserved/managed pages. */
> +extern unsigned long free_reserved_area(unsigned long start, unsigned long 
> end,
> +                                     int poison, char *s);
> +
> +static inline void adjust_managed_page_count(struct page *page, long count)
> +{
> +     totalram_pages += count;
> +}

What is the purpose of the unused page argument?

> +
> +static inline void __free_reserved_page(struct page *page)
> +{
> +     ClearPageReserved(page);
> +     init_page_count(page);
> +     __free_page(page);
> +}
This method is useful for architectures which implment HIGHMEM,
like 32 bit x86 and 32 bit sparc.
This calls for a name without underscores.


> +
> +static inline void free_reserved_page(struct page *page)
> +{
> +     __free_reserved_page(page);
> +     adjust_managed_page_count(page, 1);
> +}
> +
> +static inline void mark_page_reserved(struct page *page)
> +{
> +     SetPageReserved(page);
> +     adjust_managed_page_count(page, -1);
> +}
> +
> +static inline void free_initmem_default(int poison)
> +{

Why request user to supply the poison argumet. If this is the default
implmentation then use the default poison value too (POISON_FREE_INITMEM)

> +     extern char __init_begin[], __init_end[];
> +
> +     free_reserved_area(PAGE_ALIGN((unsigned long)&__init_begin) ,
> +                        ((unsigned long)&__init_end) & PAGE_MASK,
> +                        poison, "unused kernel");
> +}


Maybe it is just me how is not used to this area of the kernel.
But a few comments that describe what the purpose is of each
function would have helped me.

        Sam

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel