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SubjectRe: [RFC PATCH v4 7/13] memory-hotplug : remove_memory calls __remove_pages
From
On Wed, Jul 18, 2012 at 6:12 PM, Yasuaki Ishimatsu
<isimatu.yasuaki@jp.fujitsu.com> wrote:
> 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 <liuj97@gmail.com>
> 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/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);
> +

I saw a patch from Jiang Liu "mm/hotplug: free zone->pageset when a
zone becomes empty" to
free the zone->pageset and i think there may more cleanup needed when
a zone becomes empty.

We already have __add_zone() in __add_section(), what about add a
function like __remove_zone()
to do the cleanup here?

> + 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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--
Regards,
--Bob


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