From 993c1aad8f316dbafae6a0ec660ec846676838d6 Mon Sep 17 00:00:00 2001 From: Wen Congyang Date: Fri, 22 Feb 2013 16:32:50 -0800 Subject: memory-hotplug: try to offline the memory twice to avoid dependence memory can't be offlined when CONFIG_MEMCG is selected. For example: there is a memory device on node 1. The address range is [1G, 1.5G). You will find 4 new directories memory8, memory9, memory10, and memory11 under the directory /sys/devices/system/memory/. If CONFIG_MEMCG is selected, we will allocate memory to store page cgroup when we online pages. When we online memory8, the memory stored page cgroup is not provided by this memory device. But when we online memory9, the memory stored page cgroup may be provided by memory8. So we can't offline memory8 now. We should offline the memory in the reversed order. When the memory device is hotremoved, we will auto offline memory provided by this memory device. But we don't know which memory is onlined first, so offlining memory may fail. In such case, iterate twice to offline the memory. 1st iterate: offline every non primary memory block. 2nd iterate: offline primary (i.e. first added) memory block. This idea is suggested by KOSAKI Motohiro. Signed-off-by: Wen Congyang Signed-off-by: Tang Chen Cc: KOSAKI Motohiro Cc: Jiang Liu Cc: Jianguo Wu Cc: Kamezawa Hiroyuki Cc: Lai Jiangshan Cc: Wu Jianguo Cc: Yasuaki Ishimatsu Cc: Ingo Molnar Cc: Thomas Gleixner Cc: "H. Peter Anvin" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memory_hotplug.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) (limited to 'mm/memory_hotplug.c') diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 30229142995..6a82972aeae 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1387,10 +1387,13 @@ int remove_memory(u64 start, u64 size) unsigned long start_pfn, end_pfn; unsigned long pfn, section_nr; int ret; + int return_on_error = 0; + int retry = 0; start_pfn = PFN_DOWN(start); end_pfn = start_pfn + PFN_DOWN(size); +repeat: for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) { section_nr = pfn_to_section_nr(pfn); if (!present_section_nr(section_nr)) @@ -1409,14 +1412,23 @@ int remove_memory(u64 start, u64 size) ret = offline_memory_block(mem); if (ret) { - kobject_put(&mem->dev.kobj); - return ret; + if (return_on_error) { + kobject_put(&mem->dev.kobj); + return ret; + } else { + retry = 1; + } } } if (mem) kobject_put(&mem->dev.kobj); + if (retry) { + return_on_error = 1; + goto repeat; + } + return 0; } #else -- cgit v1.2.3-18-g5258