On Wed, Jun 27, 2012 at 1:44 AM, Yasuaki Ishimatsu
<isimatu.yasuaki@xxxxxxxxxxxxxx> wrote:
> When offline_pages() is called to offlined memory, the function fails since
> all memory has been offlined. In this case, the function should succeed.
> The patch adds the check function into offline_pages().
I don't understand your point. I think following misoperation should
fail. Otherwise
administrator have no way to know their fault.
$ echo offline > memoryN/state
$ echo offline > memoryN/state
In general, we don't like to ignore an error except the standard require it.
>
> CC: Len Brown <len.brown@xxxxxxxxx>
> CC: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
> CC: Paul Mackerras <paulus@xxxxxxxxx>
> CC: Christoph Lameter <cl@xxxxxxxxx>
> Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
> CC: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> CC: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
> CC: Wen Congyang <wency@xxxxxxxxxxxxxx>
> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
>
> ---
> drivers/base/memory.c | 20 ++++++++++++++++++++
> include/linux/memory.h | 1 +
> mm/memory_hotplug.c | 5 +++++
> 3 files changed, 26 insertions(+)
>
> Index: linux-3.5-rc4/drivers/base/memory.c
> ===================================================================
> --- linux-3.5-rc4.orig/drivers/base/memory.c 2012-06-26 13:28:16.726211752 +0900
> +++ linux-3.5-rc4/drivers/base/memory.c 2012-06-26 13:34:22.423639904 +0900
> @@ -70,6 +70,26 @@ void unregister_memory_isolate_notifier(
> }
> EXPORT_SYMBOL(unregister_memory_isolate_notifier);
>
> +bool memory_is_offline(unsigned long start_pfn, unsigned long end_pfn)
I dislike this function name. 'memory' is too vague to me.
> +{
> + struct memory_block *mem;
> + struct mem_section *section;
> + unsigned long pfn, section_nr;
> +
> + for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
> + section_nr = pfn_to_section_nr(pfn);
> + section = __nr_to_section(section_nr);
> + mem = find_memory_block(section);
This seems to have strong sparse dependency.
Hm, I wonder why memory-hotplug.c can enable when X86_64_ACPI_NUMA.
# eventually, we can have this option just 'select SPARSEMEM'
config MEMORY_HOTPLUG
bool "Allow for memory hot-add"
depends on SPARSEMEM || X86_64_ACPI_NUMA
> + if (!mem)
> + continue;
> + if (mem->state == MEM_OFFLINE)
> + continue;
> + return false;
> + }
> +
> + return true;
> +}
> +
> /*
> * register_memory - Setup a sysfs device for a memory block
> */
> Index: linux-3.5-rc4/include/linux/memory.h
> ===================================================================
> --- linux-3.5-rc4.orig/include/linux/memory.h 2012-06-25 04:53:04.000000000 +0900
> +++ linux-3.5-rc4/include/linux/memory.h 2012-06-26 13:34:22.424639891 +0900
> @@ -120,6 +120,7 @@ extern int memory_isolate_notify(unsigne
> extern struct memory_block *find_memory_block_hinted(struct mem_section *,
> struct memory_block *);
> extern struct memory_block *find_memory_block(struct mem_section *);
> +extern bool memory_is_offline(unsigned long start_pfn, unsigned long end_pfn);
> #define CONFIG_MEM_BLOCK_SIZE (PAGES_PER_SECTION<<PAGE_SHIFT)
> enum mem_add_context { BOOT, HOTPLUG };
> #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
> Index: linux-3.5-rc4/mm/memory_hotplug.c
> ===================================================================
> --- linux-3.5-rc4.orig/mm/memory_hotplug.c 2012-06-26 13:28:16.743211538 +0900
> +++ linux-3.5-rc4/mm/memory_hotplug.c 2012-06-26 13:48:38.264940468 +0900
> @@ -887,6 +887,11 @@ static int __ref offline_pages(unsigned
>
> lock_memory_hotplug();
>
> + if (memory_is_offline(start_pfn, end_pfn)) {
> + ret = 0;
> + goto out;
> + }
> +
> zone = page_zone(pfn_to_page(start_pfn));
> node = zone_to_nid(zone);
> nr_pages = end_pfn - start_pfn;
>
> --
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