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SubjectRe: [RFC PATCH 10/12] memory-hotplug : free memmap of sparse-vmemmap
Hi Jiang,

2012/07/01 0:58, Jiang Liu wrote:
> On 06/27/2012 01:56 PM, Yasuaki Ishimatsu wrote:
>> I don't think that all pages of virtual mapping in removed memory can be
>> freed, since page which type is MIX_SECTION_INFO is difficult to free.
>> So, the patch only frees page which type is SECTION_INFO at first.
>>
>> CC: Len Brown <len.brown@intel.com>
>> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>> CC: Paul Mackerras <paulus@samba.org>
>> CC: Christoph Lameter <cl@linux.com>
>> Cc: Minchan Kim <minchan.kim@gmail.com>
>> CC: Andrew Morton <akpm@linux-foundation.org>
>> CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
>> CC: Wen Congyang <wency@cn.fujitsu.com>
>> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
>>
>> ---
>> arch/x86/mm/init_64.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++++
>> include/linux/mm.h | 2 +
>> mm/memory_hotplug.c | 5 ++
>> mm/sparse.c | 5 +-
>> 4 files changed, 99 insertions(+), 2 deletions(-)
>>
>> Index: linux-3.5-rc4/include/linux/mm.h
>> ===================================================================
>> --- linux-3.5-rc4.orig/include/linux/mm.h 2012-06-27 09:11:13.790150442 +0900
>> +++ linux-3.5-rc4/include/linux/mm.h 2012-06-27 09:11:16.433117400 +0900
>> @@ -1588,6 +1588,8 @@ int vmemmap_populate(struct page *start_
>> void vmemmap_populate_print_last(void);
>> void register_page_bootmem_memmap(unsigned long section_nr, struct page *map,
>> unsigned long size);
>> +void vmemmap_kfree(struct page *memmpa, unsigned long nr_pages);
>> +void vmemmap_free_bootmem(struct page *memmpa, unsigned long nr_pages);
>>
>> enum mf_flags {
>> MF_COUNT_INCREASED = 1 << 0,
>> Index: linux-3.5-rc4/mm/sparse.c
>> ===================================================================
>> --- linux-3.5-rc4.orig/mm/sparse.c 2012-06-27 09:06:35.317631878 +0900
>> +++ linux-3.5-rc4/mm/sparse.c 2012-06-27 09:11:16.434117388 +0900
>> @@ -614,12 +614,13 @@ static inline struct page *kmalloc_secti
>> /* This will make the necessary allocations eventually. */
>> return sparse_mem_map_populate(pnum, nid);
>> }
>> -static void __kfree_section_memmap(struct page *memmap, unsigned long nr_pages)
>> +static void __kfree_section_memmap(struct page *page, unsigned long nr_pages)
>> {
>> - return; /* XXX: Not implemented yet */
>> + vmemmap_kfree(page, nr_pages);
>> }
>> static void free_map_bootmem(struct page *page, unsigned long nr_pages)
>> {
>> + vmemmap_free_bootmem(page, nr_pages);
>> }
>> #else
>> static struct page *__kmalloc_section_memmap(unsigned long nr_pages)
>> Index: linux-3.5-rc4/arch/x86/mm/init_64.c
>> ===================================================================
>> --- linux-3.5-rc4.orig/arch/x86/mm/init_64.c 2012-06-27 09:11:13.791150430 +0900
>> +++ linux-3.5-rc4/arch/x86/mm/init_64.c 2012-06-27 09:11:59.254581998 +0900
>> @@ -978,6 +978,95 @@ vmemmap_populate(struct page *start_page
>> return 0;
>> }
>>
>> +unsigned long find_and_clear_pte_page(unsigned long addr, unsigned long end,
>> + struct page *page)
> I think the third parameter should be "struct page **pp" instead of "struct page *page".
> And "page = pte_page(*pte)" should be "*pp = pte_page(*pte)".
> Otherwise the found page pointer can't be returned to the caller and vmemmap_kfree()
> just sees random value in variable "page".

Oh, you are right. I'll update it.

Thanks,
Yasuaki Ishimatsu

>> +{
>> + pgd_t *pgd;
>> + pud_t *pud;
>> + pmd_t *pmd;
>> + pte_t *pte;
>> + unsigned long next;
>> +
>> + page = NULL;
>> +
>> + pgd = pgd_offset_k(addr);
>> + if (pgd_none(*pgd))
>> + return PAGE_SIZE;
>> +
>> + pud = pud_offset(pgd, addr);
>> + if (pud_none(*pud))
>> + return PAGE_SIZE;
>> +
>> + if (!cpu_has_pse) {
>> + next = (addr + PAGE_SIZE) & PAGE_MASK;
>> + pmd = pmd_offset(pud, addr);
>> + if (pmd_none(*pmd))
>> + return next;
>> +
>> + pte = pte_offset_kernel(pmd, addr);
>> + if (pte_none(*pte))
>> + return next;
>> +
>> + page = pte_page(*pte);
>> + pte_clear(&init_mm, addr, pte);
>> + } else {
>> + next = pmd_addr_end(addr, end);
>> +
>> + pmd = pmd_offset(pud, addr);
>> + if (pmd_none(*pmd))
>> + return next;
>> +
>> + page = pmd_page(*pmd);
>> + pmd_clear(pmd);
>> + }
>> +
>> + return next;
>> +}
>> +
>> +void __meminit
>> +vmemmap_kfree(struct page *memmap, unsigned long nr_pages)
>> +{
>> + unsigned long addr = (unsigned long)memmap;
>> + unsigned long end = (unsigned long)(memmap + nr_pages);
>> + unsigned long next;
>> + unsigned int order;
>> + struct page *page;
>> +
>> + for (; addr < end; addr = next) {
>> + next = find_and_clear_pte_page(addr, end, page);
>> + if (!page)
>> + continue;
>> +
>> + if (is_vmalloc_addr(page))
>> + vfree(page);
>> + else {
>> + order = next - addr;
>> + free_pages((unsigned long)page,
>> + get_order(sizeof(struct page) * order));
>> + }
>> + }
>> +}
>> +
>> +void __meminit
>> +vmemmap_free_bootmem(struct page *memmap, unsigned long nr_pages)
>> +{
>> + unsigned long addr = (unsigned long)memmap;
>> + unsigned long end = (unsigned long)(memmap + nr_pages);
>> + unsigned long next;
>> + struct page *page;
>> + unsigned long magic;
>> +
>> + for (; addr < end; addr = next) {
>> + next = find_and_clear_pte_page(addr, end, page);
>> + if (!page)
>> + continue;
>> +
>> + magic = (unsigned long) page->lru.next;
>> + if (magic == SECTION_INFO)
>> + put_page_bootmem(page);
>> + }
>> +}
>> +
>> void __meminit
>> register_page_bootmem_memmap(unsigned long section_nr, struct page *start_page,
>> unsigned long size)
>> Index: linux-3.5-rc4/mm/memory_hotplug.c
>> ===================================================================
>> --- linux-3.5-rc4.orig/mm/memory_hotplug.c 2012-06-27 09:11:13.789150454 +0900
>> +++ linux-3.5-rc4/mm/memory_hotplug.c 2012-06-27 09:11:16.436117363 +0900
>> @@ -303,6 +303,8 @@ static int __meminit __add_section(int n
>> #ifdef CONFIG_SPARSEMEM_VMEMMAP
>> static int __remove_section(struct zone *zone, struct mem_section *ms)
>> {
>> + unsigned long flags;
>> + struct pglist_data *pgdat = zone->zone_pgdat;
>> int ret;
>>
>> if (!valid_section(ms))
>> @@ -310,6 +312,9 @@ static int __remove_section(struct zone
>>
>> ret = unregister_memory_section(ms);
>>
>> + pgdat_resize_lock(pgdat, &flags);
>> + sparse_remove_one_section(zone, ms);
>> + pgdat_resize_unlock(pgdat, &flags);
>> return ret;
>> }
>> #else
>>
>> --
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>>
>
>
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