Hi Jiang,

2012/07/01 0:58, Jiang Liu wrote:

On 06/27/2012 01:56 PM, Yasuaki Ishimatsu wrote:

quoted

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 <redacted>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <redacted>
CC: Christoph Lameter <redacted>
Cc: Minchan Kim <redacted>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <redacted>
CC: Wen Congyang <redacted>
Signed-off-by: Yasuaki Ishimatsu <redacted>

---
  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

quoted

+{
+	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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