Hi Wen,
2012/09/04 12:46, Wen Congyang wrote:
Hi, isimatu-san
At 09/01/2012 05:30 AM, Andrew Morton Wrote:
On Tue, 28 Aug 2012 18:00:20 +0800
wency@xxxxxxxxxxxxxx wrote:
From: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
There is a possibility that get_page_bootmem() is called to the same page many
times. So when get_page_bootmem is called to the same page, the function only
increments page->_count.
I really don't understand this explanation, even after having looked at
the code. Can you please have another attempt at the changelog?
What is the problem that you want to fix? The function get_page_bootmem()
may be called to the same page more than once, but I don't find any problem
about current implementation.
The patch is just optimization. The patch does not fix a problems.
As you know, the function may be called many times for the same page.
I think if a page is sets to page_type and Page Private flag and page->private,
the page need not be set the same things again. So we check page_type when
get_page_bootmem() is called. And if the page has been set to them, the page
is only incremented page->_count.
Thanks,
Yasuaki Ishimatsu
Thanks
Wen Congyang
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -95,10 +95,17 @@ static void release_memory_resource(struct resource *res)
static void get_page_bootmem(unsigned long info, struct page *page,
unsigned long type)
{
- page->lru.next = (struct list_head *) type;
- SetPagePrivate(page);
- set_page_private(page, info);
- atomic_inc(&page->_count);
+ unsigned long page_type;
+
+ page_type = (unsigned long) page->lru.next;
+ if (page_type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
+ page_type > MEMORY_HOTPLUG_MAX_BOOTMEM_TYPE){
+ page->lru.next = (struct list_head *) type;
+ SetPagePrivate(page);
+ set_page_private(page, info);
+ atomic_inc(&page->_count);
+ } else
+ atomic_inc(&page->_count);
}
And a code comment which explains what is going on would be good. As
is always the case ;)
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