Re: [RFC PATCH v4 7/13] memory-hotplug : remove_memory calls __remove_pages

The patch adds __remove_pages() to remove_memory(). Then the range of
phys_start_pfn argument and nr_pages argument in __remove_pagse() may
have different zone. So zone argument is removed from __remove_pages()
and __remove_pages() caluculates zone in each section.

When CONFIG_SPARSEMEM_VMEMMAP is defined, there is no way to remove a memmap.
So __remove_section only calls unregister_memory_section().

CC: David Rientjes <rientjes@google.com>
CC: Jiang Liu <redacted>
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/powerpc/platforms/pseries/hotplug-memory.c |    5 +----
 include/linux/memory_hotplug.h                  |    3 +--
 mm/memory_hotplug.c                             |   19 ++++++++++++-------
 3 files changed, 14 insertions(+), 13 deletions(-)

Index: linux-3.5-rc6/mm/memory_hotplug.c
===================================================================

--- linux-3.5-rc6.orig/mm/memory_hotplug.c      2012-07-18 18:00:27.440145432 +0900
+++ linux-3.5-rc6/mm/memory_hotplug.c   2012-07-18 18:01:02.070712487 +0900

@@ -275,11 +275,14 @@ static int __meminit __add_section(int n
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
 static int __remove_section(struct zone *zone, struct mem_section *ms)
 {
-       /*
-        * XXX: Freeing memmap with vmemmap is not implement yet.
-        *      This should be removed later.
-        */
-       return -EBUSY;
+       int ret = -EINVAL;
+
+       if (!valid_section(ms))
+               return ret;
+
+       ret = unregister_memory_section(ms);
+

+       return ret;
 }
 #else
 static int __remove_section(struct zone *zone, struct mem_section *ms)

@@ -346,11 +349,11 @@ EXPORT_SYMBOL_GPL(__add_pages);
  * sure that pages are marked reserved and zones are adjust properly by
  * calling offline_pages().
  */
-int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
-                unsigned long nr_pages)
+int __remove_pages(unsigned long phys_start_pfn, unsigned long nr_pages)
 {
        unsigned long i, ret = 0;
        int sections_to_remove;
+       struct zone *zone;

        /*
         * We can only remove entire sections

@@ -363,6 +366,7 @@ int __remove_pages(struct zone *zone, un
        sections_to_remove = nr_pages / PAGES_PER_SECTION;
        for (i = 0; i < sections_to_remove; i++) {
                unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
+               zone = page_zone(pfn_to_page(pfn));
                ret = __remove_section(zone, __pfn_to_section(pfn));
                if (ret)
                        break;

@@ -1031,6 +1035,7 @@ int __ref remove_memory(int nid, u64 sta
        /* remove memmap entry */
        firmware_map_remove(start, start + size, "System RAM");

+       __remove_pages(start >> PAGE_SHIFT, size >> PAGE_SHIFT);
 out:
        unlock_memory_hotplug();
        return ret;

Index: linux-3.5-rc6/include/linux/memory_hotplug.h
===================================================================

--- linux-3.5-rc6.orig/include/linux/memory_hotplug.h   2012-07-18 18:00:27.445145371 +0900
+++ linux-3.5-rc6/include/linux/memory_hotplug.h        2012-07-18 18:00:40.461982690 +0900

@@ -89,8 +89,7 @@ extern bool is_pageblock_removable_noloc
 /* reasonably generic interface to expand the physical pages in a zone  */
 extern int __add_pages(int nid, struct zone *zone, unsigned long start_pfn,
        unsigned long nr_pages);
-extern int __remove_pages(struct zone *zone, unsigned long start_pfn,
-       unsigned long nr_pages);
+extern int __remove_pages(unsigned long start_pfn, unsigned long nr_pages);

 #ifdef CONFIG_NUMA
 extern int memory_add_physaddr_to_nid(u64 start);

Index: linux-3.5-rc6/arch/powerpc/platforms/pseries/hotplug-memory.c
===================================================================

--- linux-3.5-rc6.orig/arch/powerpc/platforms/pseries/hotplug-memory.c  2012-07-18 18:00:27.442145407 +0900
+++ linux-3.5-rc6/arch/powerpc/platforms/pseries/hotplug-memory.c       2012-07-18 18:00:40.470982578 +0900

@@ -76,7 +76,6 @@ unsigned long memory_block_size_bytes(vo
 static int pseries_remove_memblock(unsigned long base, unsigned int memblock_size)
 {
        unsigned long start, start_pfn;
-       struct zone *zone;
        int i, ret;
        int sections_to_remove;

@@ -87,8 +86,6 @@ static int pseries_remove_memblock(unsig
                return 0;
        }

-       zone = page_zone(pfn_to_page(start_pfn));
-
        /*
         * Remove section mappings and sysfs entries for the
         * section of the memory we are removing.

@@ -101,7 +98,7 @@ static int pseries_remove_memblock(unsig
        sections_to_remove = (memblock_size >> PAGE_SHIFT) / PAGES_PER_SECTION;
        for (i = 0; i < sections_to_remove; i++) {
                unsigned long pfn = start_pfn + i * PAGES_PER_SECTION;
-               ret = __remove_pages(zone, start_pfn,  PAGES_PER_SECTION);
+               ret = __remove_pages(start_pfn,  PAGES_PER_SECTION);
                if (ret)
                        return ret;
        }

--

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