Commit 27356f54 authored Sep 11, 2013 by Toshi Kani Committed by Linus Torvalds Sep 11, 2013

mm/hotplug: verify hotplug memory range



add_memory() and remove_memory() can only handle a memory range aligned
with section.  There are problems when an unaligned range is added and
then deleted as follows:

 - add_memory() with an unaligned range succeeds, but __add_pages()
   called from add_memory() adds a whole section of pages even though
   a given memory range is less than the section size.
 - remove_memory() to the added unaligned range hits BUG_ON() in
   __remove_pages().

This patch changes add_memory() and remove_memory() to check if a given
memory range is aligned with section at the beginning.  As the result,
add_memory() fails with -EINVAL when a given range is unaligned, and does
not add such memory range.  This prevents remove_memory() to be called
with an unaligned range as well.  Note that remove_memory() has to use
BUG_ON() since this function cannot fail.

[akpm@linux-foundation.org: avoid printk warnings]
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Tang Chen <tangchen@cn.fujitsu.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 15610c86

mm/memory_hotplug.c

+23 −0

Original line number	Diff line number	Diff line
		@@ -1070,6 +1070,23 @@ int mem_online_node(int nid)
		return ret;
		}

		static int check_hotplug_memory_range(u64 start, u64 size)
		{
		u64 start_pfn = start >> PAGE_SHIFT;
		u64 nr_pages = size >> PAGE_SHIFT;

		/* Memory range must be aligned with section */
		if ((start_pfn & ~PAGE_SECTION_MASK) \|\|
		(nr_pages % PAGES_PER_SECTION) \|\| (!nr_pages)) {
		pr_err("Section-unaligned hotplug range: start 0x%llx, size 0x%llx\n",
		(unsigned long long)start,
		(unsigned long long)size);
		return -EINVAL;
		}

		return 0;
		}

		/* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
		int __ref add_memory(int nid, u64 start, u64 size)
		{
		@@ -1079,6 +1096,10 @@ int __ref add_memory(int nid, u64 start, u64 size)
		struct resource *res;
		int ret;

		ret = check_hotplug_memory_range(start, size);
		if (ret)
		return ret;

		lock_memory_hotplug();

		res = register_memory_resource(start, size);
		@@ -1786,6 +1807,8 @@ void __ref remove_memory(int nid, u64 start, u64 size)
		{
		int ret;

		BUG_ON(check_hotplug_memory_range(start, size));

		lock_memory_hotplug();

		/*