Re: [RFC v8 PATCH 13/20] memory-hotplug: check page type in get_page_bootmem
From: Andrew Morton <akpm@linux-foundation.org>
Date: 2012-08-31 21:30:37
Also in:
linux-acpi, linux-mm, linux-s390, linux-sh, lkml, sparclinux
On Tue, 28 Aug 2012 18:00:20 +0800 wency@cn.fujitsu.com wrote:
From: Yasuaki Ishimatsu <redacted> 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?
quoted hunk ↗ jump to hunk
--- 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 ;)