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Subject[PATCH v1 3/5] mm/memory_hotplug: check if sections are already online/offline
Date
Let's add some more sanity checking now that onlining/offlining code
works completely on section basis. This will make sure that we will
never try to online/offline sections that are already (or partially) in
the desired state.

Signed-off-by: David Hildenbrand <david@redhat.com>
---
include/linux/mmzone.h | 2 ++
mm/memory_hotplug.c | 5 +++++
mm/sparse.c | 28 ++++++++++++++++++++++++++++
3 files changed, 35 insertions(+)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 0859130e4db8..addfa41c047a 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1228,6 +1228,8 @@ static inline int online_section_nr(unsigned long nr)
}

#ifdef CONFIG_MEMORY_HOTPLUG
+bool mem_sections_online(unsigned long pfn, unsigned long end_pfn);
+bool mem_sections_offline(unsigned long pfn, unsigned long end_pfn);
void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn);
#ifdef CONFIG_MEMORY_HOTREMOVE
void offline_mem_sections(unsigned long start_pfn, unsigned long end_pfn);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 30d2fa42b0bb..3dc6d2a309c2 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -901,6 +901,8 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
return -EINVAL;
if (!IS_ALIGNED(nr_pages, PAGES_PER_SECTION))
return -EINVAL;
+ if (!mem_sections_offline(pfn, pfn + nr_pages))
+ return -EINVAL;

/*
* We can't use pfn_to_nid() because nid might be stored in struct page
@@ -1609,6 +1611,9 @@ int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
return -EINVAL;
if (!IS_ALIGNED(nr_pages, PAGES_PER_SECTION))
return -EINVAL;
+ if (!mem_sections_online(start_pfn, end_pfn))
+ return -EINVAL;
+
/* This makes hotplug much easier...and readable.
we assume this for now. .*/
if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start, &valid_end))
diff --git a/mm/sparse.c b/mm/sparse.c
index 10b07eea9a6e..44693cf38ca9 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -520,6 +520,34 @@ void __init sparse_init(void)

#ifdef CONFIG_MEMORY_HOTPLUG

+/* check if all mem sections are online */
+bool mem_sections_online(unsigned long pfn, unsigned long end_pfn)
+{
+ for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+ unsigned long section_nr = pfn_to_section_nr(pfn);
+
+ if (WARN_ON(!valid_section_nr(section_nr)))
+ continue;
+ if (!online_section_nr(section_nr))
+ return false;
+ }
+ return true;
+}
+
+/* check if all mem sections are offline */
+bool mem_sections_offline(unsigned long pfn, unsigned long end_pfn)
+{
+ for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+ unsigned long section_nr = pfn_to_section_nr(pfn);
+
+ if (WARN_ON(!valid_section_nr(section_nr)))
+ continue;
+ if (online_section_nr(section_nr))
+ return false;
+ }
+ return true;
+}
+
/* Mark all memory sections within the pfn range as online */
void online_mem_sections(unsigned long start_pfn, unsigned long end_pfn)
{
--
2.17.1
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