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From: Kukjin Kim on 14 Jul 2010 04:00
KAMEZAWA Hiroyuki wrote:
>
> On Wed, 14 Jul 2010 01:44:23 +0900
> Minchan Kim <minchan.kim(a)gmail.com> wrote:
>
> > > If you _really_ can't make the section size smaller, and the vast
> > > majority of the sections are fully populated, you could hack something
> > > in. We could, for instance, have a global list that's mostly readonly
> > > which tells you which sections need to be have their sizes closely
> > > inspected. That would work OK if, for instance, you only needed to
> > > check a couple of memory sections in the system. It'll start to suck
if
> > > you made the lists very long.
> >
> > Thanks for advise. As I say, I hope Russell accept 16M section.
> >
Hi,

Thanks for your inputs.
>
> It seems what I needed was good sleep....
> How about this if 16M section is not acceptable ?
>
> == NOT TESTED AT ALL, EVEN NOT COMPILED ==

Yeah...

Couldn't build with s5pv210_defconfig when used mmotm tree,
And couldn't apply your patch against latest mainline 35-rc5.

Could you please remake your patch against mainline 35-rc5?
Or...please let me know how I can test on my board(smdkv210).

>
> register address of mem_section to memmap itself's page struct's
pg->private
> field.
> This means the page is used for memmap of the section.
> Otherwise, the page is used for other purpose and memmap has a hole.
>
> ---
> arch/arm/mm/init.c | 11 ++++++++++-
> include/linux/mmzone.h | 19 ++++++++++++++++++-
> mm/sparse.c | 37
> +++++++++++++++++++++++++++++++++++++
> 3 files changed, 65 insertions(+), 2 deletions(-)
>
> Index: mmotm-2.6.35-0701/include/linux/mmzone.h
> =============================================================
> ======
> --- mmotm-2.6.35-0701.orig/include/linux/mmzone.h
> +++ mmotm-2.6.35-0701/include/linux/mmzone.h
> @@ -1047,11 +1047,28 @@ static inline struct mem_section *__pfn_
> return __nr_to_section(pfn_to_section_nr(pfn));
> }
>
> +#ifdef CONFIG_SPARSEMEM_HAS_PIT
> +void mark_memmap_pit(unsigned long start, unsigned long end, bool valid);
> +static inline int page_valid(struct mem_section *ms, unsigned long pfn)
> +{
> + struct page *page = pfn_to_page(pfn);
> + struct page *__pg = virt_to_page(page);
> + return __pg->private == ms;
> +}
> +#else
> +static inline int page_valid(struct mem_section *ms, unsigned long pfn)
> +{
> + return 1;
> +}
> +#endif
> +
> static inline int pfn_valid(unsigned long pfn)
> {
> + struct mem_section *ms;
> if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
> return 0;
> - return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
> + ms = __nr_to_section(pfn_to_section_nr(pfn));
> + return valid_section(ms) && page_valid(ms, pfn);
> }
>
> static inline int pfn_present(unsigned long pfn)
> Index: mmotm-2.6.35-0701/mm/sparse.c
> =============================================================
> ======
> --- mmotm-2.6.35-0701.orig/mm/sparse.c
> +++ mmotm-2.6.35-0701/mm/sparse.c
> @@ -615,6 +615,43 @@ void __init sparse_init(void)
> free_bootmem(__pa(usemap_map), size);
> }
>
> +#ifdef CONFIT_SPARSEMEM_HAS_PIT
> +/*
> + * Fill memmap's pg->private with a pointer to mem_section.
> + * pfn_valid() will check this later. (see include/linux/mmzone.h)
> + * The caller should call
> + * mark_memmap_pit(start, end, true) # for all allocated mem_map
> + * and, after that,
> + * mark_memmap_pit(start, end, false) # for all pits in mem_map.
> + * please see usage in ARM.
> + */
> +void mark_memmap_pit(unsigned long start, unsigned long end, bool valid)
> +{
> + struct mem_section *ms;
> + unsigned long pos, next;
> + struct page *pg;
> + void *memmap, *end;
> + unsigned long mapsize = sizeof(struct page) * PAGES_PER_SECTION;
> +
> + for (pos = start;
> + pos < end; pos = next) {
> + next = (pos + PAGES_PER_SECTION) &
> PAGE_SECTION_MASK;
> + ms = __pfn_to_section(pos);
> + if (!valid_section(ms))
> + continue;
> + for (memmap = pfn_to_page(pfn), end = pfn_to_page(next-1);
> + memmap != end + 1;
> + memmap += PAGE_SIZE) {
> + pg = virt_to_page(memmap);
> + if (valid)
> + pg->private = ms;
> + else
> + pg->private = NULL;
> + }
> + }
> +}
> +#endif
> +
> #ifdef CONFIG_MEMORY_HOTPLUG
> #ifdef CONFIG_SPARSEMEM_VMEMMAP
> static inline struct page *kmalloc_section_memmap(unsigned long pnum, int
nid,
> Index: mmotm-2.6.35-0701/arch/arm/mm/init.c
> =============================================================
> ======
> --- mmotm-2.6.35-0701.orig/arch/arm/mm/init.c
> +++ mmotm-2.6.35-0701/arch/arm/mm/init.c
> @@ -234,6 +234,13 @@ static void __init arm_bootmem_free(stru
> arch_adjust_zones(zone_size, zhole_size);
>
> free_area_init_node(0, zone_size, min, zhole_size);
> +
> +#ifdef CONFIG_SPARSEMEM
> + for_each_bank(i, mi) {
> + mark_memmap_pit(bank_start_pfn(mi->bank[i]),
> + bank_end_pfn(mi->bank[i]), true);
> + }
> +#endif
> }
>
> #ifndef CONFIG_SPARSEMEM
> @@ -386,8 +393,10 @@ free_memmap(unsigned long start_pfn, uns
> * If there are free pages between these,
> * free the section of the memmap array.
> */
> - if (pg < pgend)
> + if (pg < pgend) {
> + mark_memap_pit(pg >> PAGE_SHIFT, pgend >> PAGE_SHIFT,
> false);
> free_bootmem(pg, pgend - pg);
> + }
> }
>
> /*



Thanks.

Best regards,
Kgene.
--
Kukjin Kim <kgene.kim(a)samsung.com>, Senior Engineer,
SW Solution Development Team, Samsung Electronics Co., Ltd.

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From: KAMEZAWA Hiroyuki on 14 Jul 2010 04:20
On Wed, 14 Jul 2010 16:50:25 +0900
Kukjin Kim <kgene.kim(a)samsung.com> wrote:

> KAMEZAWA Hiroyuki wrote:
> >
> > On Wed, 14 Jul 2010 01:44:23 +0900
> > Minchan Kim <minchan.kim(a)gmail.com> wrote:
> >
> > > > If you _really_ can't make the section size smaller, and the vast
> > > > majority of the sections are fully populated, you could hack something
> > > > in. We could, for instance, have a global list that's mostly readonly
> > > > which tells you which sections need to be have their sizes closely
> > > > inspected. That would work OK if, for instance, you only needed to
> > > > check a couple of memory sections in the system. It'll start to suck
> if
> > > > you made the lists very long.
> > >
> > > Thanks for advise. As I say, I hope Russell accept 16M section.
> > >
> Hi,
>
> Thanks for your inputs.
> >
> > It seems what I needed was good sleep....
> > How about this if 16M section is not acceptable ?
> >
> > == NOT TESTED AT ALL, EVEN NOT COMPILED ==
>
> Yeah...
>
> Couldn't build with s5pv210_defconfig when used mmotm tree,
> And couldn't apply your patch against latest mainline 35-rc5.
>
> Could you please remake your patch against mainline 35-rc5?
> Or...please let me know how I can test on my board(smdkv210).
>
Ahh..how brave you are.

my patch was against mmotm-07-01.
select SPARSEMEM_HAS_PIT in config.
(in menuconfig it will appear under Processor type and features.)

This is a fixed one, maybe mm/sparce.o can be compiled.
At least, arch-generic part is compiled.

(This config should be selected automatically via arm's config.
this patch is just for test.)

Signed-off-by: KAMEZAWA hiroyuki <kamezawa.hiroyu(a)jp.fujitsu.com>
---
arch/arm/mm/init.c | 11 ++++++++++-
include/linux/mmzone.h | 19 ++++++++++++++++++-
mm/Kconfig | 5 +++++
mm/sparse.c | 38 +++++++++++++++++++++++++++++++++++++-
4 files changed, 70 insertions(+), 3 deletions(-)

Index: mmotm-2.6.35-0701/include/linux/mmzone.h
===================================================================
--- mmotm-2.6.35-0701.orig/include/linux/mmzone.h
+++ mmotm-2.6.35-0701/include/linux/mmzone.h
@@ -1047,11 +1047,28 @@ static inline struct mem_section *__pfn_
return __nr_to_section(pfn_to_section_nr(pfn));
}

+#ifdef CONFIG_SPARSEMEM_HAS_PIT
+void mark_memmap_pit(unsigned long start, unsigned long end, bool valid);
+static inline int page_valid(struct mem_section *ms, unsigned long pfn)
+{
+ struct page *page = pfn_to_page(pfn);
+ struct page *__pg = virt_to_page(page);
+ return __pg->private == ms;
+}
+#else
+static inline int page_valid(struct mem_section *ms, unsigned long pfn)
+{
+ return 1;
+}
+#endif
+
static inline int pfn_valid(unsigned long pfn)
{
+ struct mem_section *ms;
if (pfn_to_section_nr(pfn) >= NR_MEM_SECTIONS)
return 0;
- return valid_section(__nr_to_section(pfn_to_section_nr(pfn)));
+ ms = __nr_to_section(pfn_to_section_nr(pfn));
+ return valid_section(ms) && page_valid(ms, pfn);
}

static inline int pfn_present(unsigned long pfn)
Index: mmotm-2.6.35-0701/mm/sparse.c
===================================================================
--- mmotm-2.6.35-0701.orig/mm/sparse.c
+++ mmotm-2.6.35-0701/mm/sparse.c
@@ -13,7 +13,6 @@
#include <asm/dma.h>
#include <asm/pgalloc.h>
#include <asm/pgtable.h>
-
/*
* Permanent SPARSEMEM data:
*
@@ -615,6 +614,43 @@ void __init sparse_init(void)
free_bootmem(__pa(usemap_map), size);
}

+#ifdef CONFIG_SPARSEMEM_HAS_PIT
+/*
+ * Fill memmap's pg->private with a pointer to mem_section.
+ * pfn_valid() will check this later. (see include/linux/mmzone.h)
+ * The caller should call
+ * mark_memmap_pit(start, end, true) # for all allocated mem_map
+ * and, after that,
+ * mark_memmap_pit(start, end, false) # for all pits in mem_map.
+ * please see usage in ARM.
+ */
+void mark_memmap_pit(unsigned long start, unsigned long end, bool valid)
+{
+ struct mem_section *ms;
+ unsigned long pos, next;
+ struct page *pg;
+ void *memmap, *mapend;
+
+ for (pos = start;
+ pos < end; pos = next) {
+ next = (pos + PAGES_PER_SECTION) & PAGE_SECTION_MASK;
+ ms = __pfn_to_section(pos);
+ if (!valid_section(ms))
+ continue;
+ for (memmap = (void*)pfn_to_page(pos),
+ mapend = pfn_to_page(next-1); /* the last page in section*/
+ memmap < mapend;
+ memmap += PAGE_SIZE) {
+ pg = virt_to_page(memmap);
+ if (valid)
+ pg->private = (unsigned long)ms;
+ else
+ pg->private = 0;
+ }
+ }
+}
+#endif
+
#ifdef CONFIG_MEMORY_HOTPLUG
#ifdef CONFIG_SPARSEMEM_VMEMMAP
static inline struct page *kmalloc_section_memmap(unsigned long pnum, int nid,
Index: mmotm-2.6.35-0701/arch/arm/mm/init.c
===================================================================
--- mmotm-2.6.35-0701.orig/arch/arm/mm/init.c
+++ mmotm-2.6.35-0701/arch/arm/mm/init.c
@@ -234,6 +234,13 @@ static void __init arm_bootmem_free(stru
arch_adjust_zones(zone_size, zhole_size);

free_area_init_node(0, zone_size, min, zhole_size);
+
+#ifdef CONFIG_SPARSEMEM
+ for_each_bank(i, mi) {
+ mark_memmap_pit(bank_start_pfn(mi->bank[i]),
+ bank_end_pfn(mi->bank[i]), true);
+ }
+#endif
}

#ifndef CONFIG_SPARSEMEM
@@ -386,8 +393,10 @@ free_memmap(unsigned long start_pfn, uns
* If there are free pages between these,
* free the section of the memmap array.
*/
- if (pg < pgend)
+ if (pg < pgend) {
+ mark_memap_pit(pg >> PAGE_SHIFT, pgend >> PAGE_SHIFT, false);
free_bootmem(pg, pgend - pg);
+ }
}

/*
Index: mmotm-2.6.35-0701/mm/Kconfig
===================================================================
--- mmotm-2.6.35-0701.orig/mm/Kconfig
+++ mmotm-2.6.35-0701/mm/Kconfig
@@ -128,6 +128,11 @@ config SPARSEMEM_VMEMMAP
pfn_to_page and page_to_pfn operations. This is the most
efficient option when sufficient kernel resources are available.

+config SPAESEMEM_HAS_PIT
+ bool "allow holes in sparsemem's memmap"
+ depends on SPARSEMEM && !SPARSEMEM_VMEMMAP
+ default n
+
# eventually, we can have this option just 'select SPARSEMEM'
config MEMORY_HOTPLUG
bool "Allow for memory hot-add"

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