Commit 27356f54 authored by Toshi Kani's avatar Toshi Kani Committed by Linus Torvalds
Browse files

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

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.

[ avoid printk warnings]
Signed-off-by: default avatarToshi Kani <>
Acked-by: default avatarKOSAKI Motohiro <>
Reviewed-by: default avatarTang Chen <>
Reviewed-by: default avatarWanpeng Li <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 15610c86
......@@ -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;
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));
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