Messages in this thread Patch in this message | | | From | Toshi Kani <> | Subject | [PATCH] mm/hotplug: Verify hotplug memory range | Date | Thu, 8 Aug 2013 10:47:40 -0600 |
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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.
Signed-off-by: Toshi Kani <toshi.kani@hp.com> --- mm/memory_hotplug.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+)
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index ca1dd3a..ac182de 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1069,6 +1069,22 @@ out: 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("Unsupported hotplug range: start 0x%llx, size 0x%llx\n", + start, 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) { @@ -1078,6 +1094,10 @@ 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 +1806,8 @@ void __ref remove_memory(int nid, u64 start, u64 size) { int ret; + BUG_ON(check_hotplug_memory_range(start, size)); + lock_memory_hotplug(); /*
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