[PATCH v2, part1 01/29] mm: introduce common help functions to deal with reserved/managed pages

[PATCH v2, part1 01/29] mm: introduce common help functions to deal with reserved/managed pages

[Jiang Liu]

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@huawei.com>
---
 include/linux/mm.h |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
 mm/page_alloc.c    |   20 ++++++++++++++++++++
 2 files changed, 68 insertions(+)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7acc9dc..d75c14b 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1295,6 +1295,54 @@ 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);
 
+/*
+ * Free reserved pages within range [PAGE_ALIGN(start), end & PAGE_MASK)
+ * into the buddy system. The freed pages will be poisoned with pattern
+ * "poison" if it's non-zero.
+ * Return pages freed into the buddy system.
+ */
+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;
+}
+
+/* Free the reserved page into the buddy system, so it gets managed. */
+static inline void __free_reserved_page(struct page *page)
+{
+	ClearPageReserved(page);
+	init_page_count(page);
+	__free_page(page);
+}
+
+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);
+}
+
+/*
+ * Default method to free all the __init memory into the buddy system.
+ * The freed pages will be poisoned with pattern "poison" if it is
+ * non-zero. Return pages freed into the buddy system.
+ */
+static inline unsigned long free_initmem_default(int poison)
+{
+	extern char __init_begin[], __init_end[];
+
+	return free_reserved_area(PAGE_ALIGN((unsigned long)&__init_begin) ,
+				  ((unsigned long)&__init_end) & PAGE_MASK,
+				  poison, "unused kernel");
+}
+
 #ifdef CONFIG_HAVE_MEMBLOCK_NODE_MAP
 /*
  * With CONFIG_HAVE_MEMBLOCK_NODE_MAP set, an architecture may initialise its
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 8fcced7..0fadb09 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5113,6 +5113,26 @@ early_param("movablecore", cmdline_parse_movablecore);
 
 #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
 
+unsigned long free_reserved_area(unsigned long start, unsigned long end,
+				 int poison, char *s)
+{
+	unsigned long pages, pos;
+
+	pos = start = PAGE_ALIGN(start);
+	end &= PAGE_MASK;
+	for (pages = 0; pos < end; pos += PAGE_SIZE, pages++) {
+		if (poison)
+			memset((void *)pos, poison, PAGE_SIZE);
+		free_reserved_page(virt_to_page(pos));
+	}
+
+	if (pages && s)
+		pr_info("Freeing %s memory: %ldK (%lx - %lx)\n",
+			s, pages << (PAGE_SHIFT - 10), start, end);
+
+	return pages;
+}
+
 /**
  * set_dma_reserve - set the specified number of pages reserved in the first zone
  * @new_dma_reserve: The number of pages to mark reserved
-- 
1.7.9.5

Re: [PATCH v2, part1 01/29] mm: introduce common help functions to deal with reserved/managed pages

[Geert Uytterhoeven]

On Sun, Mar 10, 2013 at 7:26 AM, Jiang Liu <liuj97@gmail.com> 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@huawei.com>

I have a few minor comments (see below), but apart from that:
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>

> ---
>  include/linux/mm.h |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
>  mm/page_alloc.c    |   20 ++++++++++++++++++++
>  2 files changed, 68 insertions(+)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 7acc9dc..d75c14b 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1295,6 +1295,54 @@ 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);
>
> +/*
> + * Free reserved pages within range [PAGE_ALIGN(start), end & PAGE_MASK)
> + * into the buddy system. The freed pages will be poisoned with pattern
> + * "poison" if it's non-zero.

What if you want to poison with zero?
As poison is a full int, but memset only uses the least-significant
byte, you can
change it to poison if it's positive (i.e. >= 0)?

> +/*
> + * Default method to free all the __init memory into the buddy system.
> + * The freed pages will be poisoned with pattern "poison" if it is
> + * non-zero. Return pages freed into the buddy system.
> + */
> +static inline unsigned long free_initmem_default(int poison)
> +{
> +       extern char __init_begin[], __init_end[];
> +
> +       return free_reserved_area(PAGE_ALIGN((unsigned long)&__init_begin) ,
> +                                 ((unsigned long)&__init_end) & PAGE_MASK,

The "PAGE_ALIGN(...)" and "& PAGE_MASK" are superfluous, as
free_reserved_area() already does that.

> +                                 poison, "unused kernel");
> +}
> +

> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 8fcced7..0fadb09 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5113,6 +5113,26 @@ early_param("movablecore", cmdline_parse_movablecore);
>
>  #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
>
> +unsigned long free_reserved_area(unsigned long start, unsigned long end,
> +                                int poison, char *s)
> +{

> +       if (pages && s)
> +               pr_info("Freeing %s memory: %ldK (%lx - %lx)\n",

"%luKiB (0x%lx - 0x%lx)"?

> +                       s, pages << (PAGE_SHIFT - 10), start, end);
> +
> +       return pages;
> +}

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH v2, part1 01/29] mm: introduce common help functions to deal with reserved/managed pages

[Jiang Liu]

Hi Geert,
	Thanks for review!

On 03/10/2013 05:20 PM, Geert Uytterhoeven wrote:
> On Sun, Mar 10, 2013 at 7:26 AM, Jiang Liu <liuj97@gmail.com> 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@huawei.com>
> 
> I have a few minor comments (see below), but apart from that:
> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
> 
>> ---
>>  include/linux/mm.h |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
>>  mm/page_alloc.c    |   20 ++++++++++++++++++++
>>  2 files changed, 68 insertions(+)
>>
>> diff --git a/include/linux/mm.h b/include/linux/mm.h
>> index 7acc9dc..d75c14b 100644
>> --- a/include/linux/mm.h
>> +++ b/include/linux/mm.h
>> @@ -1295,6 +1295,54 @@ 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);
>>
>> +/*
>> + * Free reserved pages within range [PAGE_ALIGN(start), end & PAGE_MASK)
>> + * into the buddy system. The freed pages will be poisoned with pattern
>> + * "poison" if it's non-zero.
> 
> What if you want to poison with zero?
> As poison is a full int, but memset only uses the least-significant
> byte, you can
> change it to poison if it's positive (i.e. >= 0)?
Good point, ARM64 does poison memory with 0. Will implement that way in next version.

> 
>> +/*
>> + * Default method to free all the __init memory into the buddy system.
>> + * The freed pages will be poisoned with pattern "poison" if it is
>> + * non-zero. Return pages freed into the buddy system.
>> + */
>> +static inline unsigned long free_initmem_default(int poison)
>> +{
>> +       extern char __init_begin[], __init_end[];
>> +
>> +       return free_reserved_area(PAGE_ALIGN((unsigned long)&__init_begin) ,
>> +                                 ((unsigned long)&__init_end) & PAGE_MASK,
> 
> The "PAGE_ALIGN(...)" and "& PAGE_MASK" are superfluous, as
> free_reserved_area() already does that.
Will remove the redundant ops next version.

> 
>> +                                 poison, "unused kernel");
>> +}
>> +
> 
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index 8fcced7..0fadb09 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -5113,6 +5113,26 @@ early_param("movablecore", cmdline_parse_movablecore);
>>
>>  #endif /* CONFIG_HAVE_MEMBLOCK_NODE_MAP */
>>
>> +unsigned long free_reserved_area(unsigned long start, unsigned long end,
>> +                                int poison, char *s)
>> +{
> 
>> +       if (pages && s)
>> +               pr_info("Freeing %s memory: %ldK (%lx - %lx)\n",
> 
> "%luKiB (0x%lx - 0x%lx)"?
Sure.

Regards!
Gerry

> 
>> +                       s, pages << (PAGE_SHIFT - 10), start, end);
>> +
>> +       return pages;
>> +}
> 
> Gr{oetje,eeting}s,
> 
>                         Geert
> 
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
> 
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds
>