[RFC PATCH 6/8] memory-hotplug: introduce new function arch_remove_memory()

[Wen Congyang <wency@cn.fujitsu.com>]

We don't call __add_pages() directly in the function add_memory()
because some other architecture related thins needs to be done
before or after calling __add_pages(). So we should not call
__remove_pages() directly in the function remove_memory.
Introduce new function arch_remove_memory() to revert the things done
in arch_add_memory().

Note: the function for x86_64 will be implemented later. And I don't
know how to implement it for s390.

CC: David Rientjes <rientjes@google.com>
CC: Jiang Liu <liuj97@gmail.com>
CC: Len Brown <len.brown@intel.com>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Paul Mackerras <paulus@samba.org>
CC: Christoph Lameter <cl@linux.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
CC: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
---
 arch/ia64/mm/init.c            |   16 ++++++++++++++++
 arch/powerpc/mm/mem.c          |   14 ++++++++++++++
 arch/s390/mm/init.c            |    8 ++++++++
 arch/sh/mm/init.c              |   15 +++++++++++++++
 arch/tile/mm/init.c            |    8 ++++++++
 arch/x86/mm/init_32.c          |   10 ++++++++++
 arch/x86/mm/init_64.c          |    7 +++++++
 include/linux/memory_hotplug.h |    1 +
 mm/memory_hotplug.c            |    2 +-
 9 files changed, 80 insertions(+), 1 deletions(-)

diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
index 0eab454..1e345ed 100644
--- a/arch/ia64/mm/init.c
+++ b/arch/ia64/mm/init.c
@@ -688,6 +688,22 @@ int arch_add_memory(int nid, u64 start, u64 size)
 
 	return ret;
 }
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+int arch_remove_memory(u64 start, u64 size)
+{
+	unsigned long start_pfn = start >> PAGE_SHIFT;
+	unsigned long nr_pages = size >> PAGE_SHIFT;
+	int ret;
+
+	ret = __remove_pages(start_pfn, nr_pages);
+	if (ret)
+		pr_warn("%s: Problem encountered in __remove_pages() as"
+			" ret=%d\n", __func__,  ret);
+
+	return ret;
+}
+#endif
 #endif
 
 /*
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index baaafde..249cef4 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -133,6 +133,20 @@ int arch_add_memory(int nid, u64 start, u64 size)
 
 	return __add_pages(nid, zone, start_pfn, nr_pages);
 }
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+int arch_remove_memory(u64 start, u64 size)
+{
+	unsigned long start_pfn = start >> PAGE_SHIFT;
+	unsigned long nr_pages = size >> PAGE_SHIFT;
+
+	start = (unsigned long)__va(start);
+	if (remove_section_mapping(start, start + size))
+		return -EINVAL;
+
+	return __remove_pages(start_pfn, nr_pages);
+}
+#endif
 #endif /* CONFIG_MEMORY_HOTPLUG */
 
 /*
diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
index 2bea060..3de0d5b 100644
--- a/arch/s390/mm/init.c
+++ b/arch/s390/mm/init.c
@@ -259,4 +259,12 @@ int arch_add_memory(int nid, u64 start, u64 size)
 		vmem_remove_mapping(start, size);
 	return rc;
 }
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+int arch_remove_memory(u64 start, u64 size)
+{
+	/* TODO */
+	return -EBUSY;
+}
+#endif
 #endif /* CONFIG_MEMORY_HOTPLUG */
diff --git a/arch/sh/mm/init.c b/arch/sh/mm/init.c
index 82cc576..fc84491 100644
--- a/arch/sh/mm/init.c
+++ b/arch/sh/mm/init.c
@@ -558,4 +558,19 @@ int memory_add_physaddr_to_nid(u64 addr)
 EXPORT_SYMBOL_GPL(memory_add_physaddr_to_nid);
 #endif
 
+#ifdef CONFIG_MEMORY_HOTREMOVE
+int arch_remove_memory(u64 start, u64 size)
+{
+	unsigned long start_pfn = start >> PAGE_SHIFT;
+	unsigned long nr_pages = size >> PAGE_SHIFT;
+	int ret;
+
+	ret = __remove_pages(start_pfn, nr_pages);
+	if (unlikely(ret))
+		pr_warn("%s: Failed, __remove_pages() == %d\n", __func__,
+			ret);
+
+	return ret;
+}
+#endif
 #endif /* CONFIG_MEMORY_HOTPLUG */
diff --git a/arch/tile/mm/init.c b/arch/tile/mm/init.c
index 630dd2c..bdd8a99 100644
--- a/arch/tile/mm/init.c
+++ b/arch/tile/mm/init.c
@@ -947,6 +947,14 @@ int remove_memory(u64 start, u64 size)
 {
 	return -EINVAL;
 }
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+int arch_remove_memory(u64 start, u64 size)
+{
+	/* TODO */
+	return -EBUSY;
+}
+#endif
 #endif
 
 struct kmem_cache *pgd_cache;
diff --git a/arch/x86/mm/init_32.c b/arch/x86/mm/init_32.c
index 575d86f..a690153 100644
--- a/arch/x86/mm/init_32.c
+++ b/arch/x86/mm/init_32.c
@@ -842,6 +842,16 @@ int arch_add_memory(int nid, u64 start, u64 size)
 
 	return __add_pages(nid, zone, start_pfn, nr_pages);
 }
+
+#ifdef CONFIG_MEMORY_HOTREMOVE
+int arch_remove_memory(unsigned long start, unsigned long size)
+{
+	unsigned long start_pfn = start >> PAGE_SHIFT;
+	unsigned long nr_pages = size >> PAGE_SHIFT;
+
+	return __remove_pages(start_pfn, nr_pages);
+}
+#endif
 #endif
 
 /*
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index 9e635b3..78b94bc 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -675,6 +675,13 @@ int arch_add_memory(int nid, u64 start, u64 size)
 }
 EXPORT_SYMBOL_GPL(arch_add_memory);
 
+#ifdef CONFIG_MEMORY_HOTREMOVE
+int arch_remove_memory(unsigned long start, unsigned long size)
+{
+	/* TODO */
+	return -EBUSY;
+}
+#endif
 #endif /* CONFIG_MEMORY_HOTPLUG */
 
 static struct kcore_list kcore_vsyscall;
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 2ba0a1a..8639799 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -84,6 +84,7 @@ extern void __online_page_free(struct page *page);
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 extern bool is_pageblock_removable_nolock(struct page *page);
+extern int arch_remove_memory(unsigned long start, unsigned long size);
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
 /* reasonably generic interface to expand the physical pages in a zone  */
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index dccdf71..cc2c8b9 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1055,7 +1055,7 @@ int __ref remove_memory(int nid, u64 start, u64 size)
 		unregister_one_node(nid);
 	}
 
-	__remove_pages(start >> PAGE_SHIFT, size >> PAGE_SHIFT);
+	arch_remove_memory(start, size);
 out:
 	unlock_memory_hotplug();
 	return ret;
-- 
1.7.1

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