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Message-id: <000e01cb2329$3d8c5770$b8a50650$%kim@samsung.com>
Date: Wed, 14 Jul 2010 16:50:25 +0900
From: Kukjin Kim <kgene.kim@...sung.com>
To: 'KAMEZAWA Hiroyuki' <kamezawa.hiroyu@...fujitsu.com>,
'Minchan Kim' <minchan.kim@...il.com>
Cc: 'Dave Hansen' <dave@...ux.vnet.ibm.com>,
'Johannes Weiner' <hannes@...xchg.org>, linux@....linux.org.uk,
'Yinghai Lu' <yinghai@...nel.org>,
"'H. Peter Anvin'" <hpa@...or.com>,
'Andrew Morton' <akpm@...ux-foundation.org>,
'Shaohua Li' <shaohua.li@...el.com>,
'Yakui Zhao' <yakui.zhao@...el.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org,
arm-kernel@...ts.infradead.org, 'Mel Gorman' <mel@....ul.ie>
Subject: RE: [RFC] Tight check of pfn_valid on sparsemem
KAMEZAWA Hiroyuki wrote:
>
> On Wed, 14 Jul 2010 01:44:23 +0900
> Minchan Kim <minchan.kim@...il.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@...sung.com>, Senior Engineer,
SW Solution Development Team, Samsung Electronics Co., Ltd.
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