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authorYasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>2013-02-22 16:32:52 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-23 17:50:11 -0800
commit6677e3eaf4d78abd7b09133414c05dc3ec353e7f (patch)
tree62898a335513651e498d0ace2eb0f554d2ddc0bb
parent993c1aad8f316dbafae6a0ec660ec846676838d6 (diff)
memory-hotplug: check whether all memory blocks are offlined or not when removing memory
We remove the memory like this: 1. lock memory hotplug 2. offline a memory block 3. unlock memory hotplug 4. repeat 1-3 to offline all memory blocks 5. lock memory hotplug 6. remove memory(TODO) 7. unlock memory hotplug All memory blocks must be offlined before removing memory. But we don't hold the lock in the whole operation. So we should check whether all memory blocks are offlined before step6. Otherwise, kernel maybe panicked. Offlining a memory block and removing a memory device can be two different operations. Users can just offline some memory blocks without removing the memory device. For this purpose, the kernel has held lock_memory_hotplug() in __offline_pages(). To reuse the code for memory hot-remove, we repeat step 1-3 to offline all the memory blocks, repeatedly lock and unlock memory hotplug, but not hold the memory hotplug lock in the whole operation. Signed-off-by: Wen Congyang <wency@cn.fujitsu.com> Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Jiang Liu <jiang.liu@huawei.com> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: Wu Jianguo <wujianguo@huawei.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/base/memory.c6
-rw-r--r--include/linux/memory_hotplug.h1
-rw-r--r--mm/memory_hotplug.c48
3 files changed, 55 insertions, 0 deletions
diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 83d0b17ba1c..a51007b7903 100644
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -693,6 +693,12 @@ int offline_memory_block(struct memory_block *mem)
return ret;
}
+/* return true if the memory block is offlined, otherwise, return false */
+bool is_memblock_offlined(struct memory_block *mem)
+{
+ return mem->state == MEM_OFFLINE;
+}
+
/*
* Initialize the sysfs support for memory devices...
*/
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 4a45c4e5002..8dd0950a6a7 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -247,6 +247,7 @@ extern int add_memory(int nid, u64 start, u64 size);
extern int arch_add_memory(int nid, u64 start, u64 size);
extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
extern int offline_memory_block(struct memory_block *mem);
+extern bool is_memblock_offlined(struct memory_block *mem);
extern int remove_memory(u64 start, u64 size);
extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
int nr_pages);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 6a82972aeae..5d350f5c68e 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1429,6 +1429,54 @@ repeat:
goto repeat;
}
+ lock_memory_hotplug();
+
+ /*
+ * we have offlined all memory blocks like this:
+ * 1. lock memory hotplug
+ * 2. offline a memory block
+ * 3. unlock memory hotplug
+ *
+ * repeat step1-3 to offline the memory block. All memory blocks
+ * must be offlined before removing memory. But we don't hold the
+ * lock in the whole operation. So we should check whether all
+ * memory blocks are offlined.
+ */
+
+ mem = NULL;
+ for (pfn = start_pfn; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+ section_nr = pfn_to_section_nr(pfn);
+ if (!present_section_nr(section_nr))
+ continue;
+
+ section = __nr_to_section(section_nr);
+ /* same memblock? */
+ if (mem)
+ if ((section_nr >= mem->start_section_nr) &&
+ (section_nr <= mem->end_section_nr))
+ continue;
+
+ mem = find_memory_block_hinted(section, mem);
+ if (!mem)
+ continue;
+
+ ret = is_memblock_offlined(mem);
+ if (!ret) {
+ pr_warn("removing memory fails, because memory "
+ "[%#010llx-%#010llx] is onlined\n",
+ PFN_PHYS(section_nr_to_pfn(mem->start_section_nr)),
+ PFN_PHYS(section_nr_to_pfn(mem->end_section_nr + 1)) - 1);
+
+ kobject_put(&mem->dev.kobj);
+ unlock_memory_hotplug();
+ return ret;
+ }
+ }
+
+ if (mem)
+ kobject_put(&mem->dev.kobj);
+ unlock_memory_hotplug();
+
return 0;
}
#else