From 27356f54c8c32609ff45b4ed333bb64fb2eef374 Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Wed, 11 Sep 2013 14:21:49 -0700 Subject: [PATCH] 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 Acked-by: KOSAKI Motohiro Reviewed-by: Tang Chen Reviewed-by: Wanpeng Li Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory_hotplug.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 46b489cacdd8..247d66675a91 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1070,6 +1070,23 @@ 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("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(); /* -- 2.20.1