The patch titled
Subject: memory-hotplug: check whether all memory blocks are offlined or not when removing memory
has been added to the -mm tree. Its filename is
memory-hotplug-check-whether-all-memory-blocks-are-offlined-or-not-when-removing-memory.patch
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From: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
Subject: 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.
Signed-off-by: Wen Congyang <wency@xxxxxxxxxxxxxx>
Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
Signed-off-by: Tang Chen <tangchen@xxxxxxxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Jiang Liu <jiang.liu@xxxxxxxxxx>
Cc: Jianguo Wu <wujianguo@xxxxxxxxxx>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Cc: Wu Jianguo <wujianguo@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/base/memory.c | 6 +++
include/linux/memory_hotplug.h | 1
mm/memory_hotplug.c | 48 +++++++++++++++++++++++++++++++
3 files changed, 55 insertions(+)
diff -puN drivers/base/memory.c~memory-hotplug-check-whether-all-memory-blocks-are-offlined-or-not-when-removing-memory drivers/base/memory.c
--- a/drivers/base/memory.c~memory-hotplug-check-whether-all-memory-blocks-are-offlined-or-not-when-removing-memory
+++ a/drivers/base/memory.c
@@ -693,6 +693,12 @@ int offline_memory_block(struct memory_b
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 -puN include/linux/memory_hotplug.h~memory-hotplug-check-whether-all-memory-blocks-are-offlined-or-not-when-removing-memory include/linux/memory_hotplug.h
--- a/include/linux/memory_hotplug.h~memory-hotplug-check-whether-all-memory-blocks-are-offlined-or-not-when-removing-memory
+++ a/include/linux/memory_hotplug.h
@@ -247,6 +247,7 @@ extern int add_memory(int nid, u64 start
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 -puN mm/memory_hotplug.c~memory-hotplug-check-whether-all-memory-blocks-are-offlined-or-not-when-removing-memory mm/memory_hotplug.c
--- a/mm/memory_hotplug.c~memory-hotplug-check-whether-all-memory-blocks-are-offlined-or-not-when-removing-memory
+++ a/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
_
Patches currently in -mm which might be from isimatu.yasuaki@xxxxxxxxxxxxxx are
x86-fix-the-argument-passed-to-sync_global_pgds.patch
x86-make-mem=-option-to-work-for-efi-platform.patch
memory-hotplug-try-to-offline-the-memory-twice-to-avoid-dependence.patch
memory-hotplug-check-whether-all-memory-blocks-are-offlined-or-not-when-removing-memory.patch
memory-hotplug-remove-redundant-codes.patch
memory-hotplug-remove-sys-firmware-memmap-x-sysfs.patch
memory-hotplug-introduce-new-arch_remove_memory-for-removing-page-table.patch
memory-hotplug-implement-register_page_bootmem_info_section-of-sparse-vmemmap.patch
memory-hotplug-move-pgdat_resize_lock-into-sparse_remove_one_section.patch
memory-hotplug-common-apis-to-support-page-tables-hot-remove.patch
memory-hotplug-remove-page-table-of-x86_64-architecture.patch
memory-hotplug-remove-memmap-of-sparse-vmemmap.patch
memory-hotplug-integrated-__remove_section-of-config_sparsemem_vmemmap.patch
memory_hotplug-clear-zone-when-removing-the-memory.patch
memory-hotplug-remove-sysfs-file-of-node.patch
memory-hotplug-free-node_data-when-a-node-is-offlined.patch
memory-hotplug-do-not-allocate-pdgat-if-it-was-not-freed-when-offline.patch
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