Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [ 049/127] memory hotplug: fix section info double registration bug | Date | Fri, 28 Sep 2012 13:33:42 -0700 |
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3.0-stable review patch. If anyone has any objections, please let me know.
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From: qiuxishi <qiuxishi@gmail.com>
commit f14851af0ebb32745c6c5a2e400aa0549f9d20df upstream.
There may be a bug when registering section info. For example, on my Itanium platform, the pfn range of node0 includes the other nodes, so other nodes' section info will be double registered, and memmap's page count will equal to 3.
node0: start_pfn=0x100, spanned_pfn=0x20fb00, present_pfn=0x7f8a3, => 0x000100-0x20fc00 node1: start_pfn=0x80000, spanned_pfn=0x80000, present_pfn=0x80000, => 0x080000-0x100000 node2: start_pfn=0x100000, spanned_pfn=0x80000, present_pfn=0x80000, => 0x100000-0x180000 node3: start_pfn=0x180000, spanned_pfn=0x80000, present_pfn=0x80000, => 0x180000-0x200000
free_all_bootmem_node() register_page_bootmem_info_node() register_page_bootmem_info_section()
When hot remove memory, we can't free the memmap's page because page_count() is 2 after put_page_bootmem().
sparse_remove_one_section() free_section_usemap() free_map_bootmem() put_page_bootmem()
[akpm@linux-foundation.org: add code comment] Signed-off-by: Xishi Qiu <qiuxishi@huawei.com> Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: "Luck, Tony" <tony.luck@intel.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- mm/memory_hotplug.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)
--- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -116,9 +116,6 @@ static void register_page_bootmem_info_s struct mem_section *ms; struct page *page, *memmap; - if (!pfn_valid(start_pfn)) - return; - section_nr = pfn_to_section_nr(start_pfn); ms = __nr_to_section(section_nr); @@ -177,9 +174,16 @@ void register_page_bootmem_info_node(str end_pfn = pfn + pgdat->node_spanned_pages; /* register_section info */ - for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) - register_page_bootmem_info_section(pfn); - + for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) { + /* + * Some platforms can assign the same pfn to multiple nodes - on + * node0 as well as nodeN. To avoid registering a pfn against + * multiple nodes we check that this pfn does not already + * reside in some other node. + */ + if (pfn_valid(pfn) && (pfn_to_nid(pfn) == node)) + register_page_bootmem_info_section(pfn); + } } #endif /* !CONFIG_SPARSEMEM_VMEMMAP */
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