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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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    >





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