This patch contains online_page_chain and apropriate functions
for registering/unregistering online page notifiers. It allows
to do some machine specific tasks during online page stage which
is required to implement memory hotplug in virtual machines.
Additionally, __online_page_increment_counters() and
__online_page_free() function was add to ease generic
hotplug operation.
Signed-off-by: Daniel Kiper <dkiper@xxxxxxxxxxxx>
---
include/linux/memory_hotplug.h | 11 ++++-
mm/memory_hotplug.c | 82 ++++++++++++++++++++++++++++++++++++++-
2 files changed, 88 insertions(+), 5 deletions(-)
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 8122018..d8cc963 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -12,6 +12,9 @@ struct mem_section;
#ifdef CONFIG_MEMORY_HOTPLUG
+#define OP_DO_NOT_INCREMENT_TOTAL_COUNTERS 0
+#define OP_INCREMENT_TOTAL_COUNTERS 1
+
/*
* Types for free bootmem stored in page->lru.next. These have to be in
* some random range in unsigned long space for debugging purposes.
@@ -68,12 +71,16 @@ static inline void zone_seqlock_init(struct zone *zone)
extern int zone_grow_free_lists(struct zone *zone, unsigned long new_nr_pages);
extern int zone_grow_waitqueues(struct zone *zone, unsigned long nr_pages);
extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
-/* need some defines for these for archs that don't support it */
-extern void online_page(struct page *page);
/* VM interface that may be used by firmware interface */
extern int online_pages(unsigned long, unsigned long);
extern void __offline_isolated_pages(unsigned long, unsigned long);
+extern int register_online_page_notifier(struct notifier_block *nb);
+extern int unregister_online_page_notifier(struct notifier_block *nb);
+
+void __online_page_increment_counters(struct page *page, int inc_total);
+void __online_page_free(struct page *page);
+
#ifdef CONFIG_MEMORY_HOTREMOVE
extern bool is_pageblock_removable_nolock(struct page *page);
#endif /* CONFIG_MEMORY_HOTREMOVE */
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index f0651ae..2f62e26 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -29,11 +29,23 @@
#include <linux/suspend.h>
#include <linux/mm_inline.h>
#include <linux/firmware-map.h>
+#include <linux/notifier.h>
#include <asm/tlbflush.h>
#include "internal.h"
+/*
+ * online_page_chain contains chain of notifiers called when page is onlined.
+ * When kernel is booting generic_online_page_notifier() is registered with
+ * priority 0 as default notifier. Custom notifier should be registered with
+ * priority > 0. It could be terminal (it should return NOTIFY_STOP on success)
+ * or not (it should return NOTIFY_DONE or NOTIFY_OK on success; for full list
+ * of return codes look into include/linux/notifier.h).
+ */
+
+static RAW_NOTIFIER_HEAD(online_page_chain);
+
DEFINE_MUTEX(mem_hotplug_mutex);
void lock_memory_hotplug(void)
@@ -361,27 +373,91 @@ int __remove_pages(struct zone *zone, unsigned long
phys_start_pfn,
}
EXPORT_SYMBOL_GPL(__remove_pages);
-void online_page(struct page *page)
+int register_online_page_notifier(struct notifier_block *nb)
+{
+ int rc;
+
+ lock_memory_hotplug();
+ rc = raw_notifier_chain_register(&online_page_chain, nb);
+ unlock_memory_hotplug();
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(register_online_page_notifier);
+
+int unregister_online_page_notifier(struct notifier_block *nb)
+{
+ int rc;
+
+ lock_memory_hotplug();
+ rc = raw_notifier_chain_unregister(&online_page_chain, nb);
+ unlock_memory_hotplug();
+
+ return rc;
+}
+EXPORT_SYMBOL_GPL(unregister_online_page_notifier);
+
+void __online_page_increment_counters(struct page *page, int inc_total)
{
unsigned long pfn = page_to_pfn(page);
- totalram_pages++;
+ if (inc_total == OP_INCREMENT_TOTAL_COUNTERS)
+ totalram_pages++;
+
if (pfn >= num_physpages)
num_physpages = pfn + 1;
#ifdef CONFIG_HIGHMEM
- if (PageHighMem(page))
+ if (inc_total == OP_INCREMENT_TOTAL_COUNTERS && PageHighMem(page))
totalhigh_pages++;
#endif
#ifdef CONFIG_FLATMEM
max_mapnr = max(pfn, max_mapnr);
#endif
+}
+EXPORT_SYMBOL_GPL(__online_page_increment_counters);
+void __online_page_free(struct page *page)
+{
ClearPageReserved(page);
init_page_count(page);
__free_page(page);
}
+EXPORT_SYMBOL_GPL(__online_page_free);
+
+static int generic_online_page_notifier(struct notifier_block *nb, unsigned
long val, void *v)
+{
+ struct page *page = v;
+
+ __online_page_increment_counters(page, OP_INCREMENT_TOTAL_COUNTERS);
+ __online_page_free(page);
+
+ return NOTIFY_OK;
+}
+
+/*
+ * 0 priority makes this the fallthrough default. All
+ * architectures wanting to override this should set
+ * a higher priority and return NOTIFY_STOP to keep
+ * this from running.
+ */
+
+static struct notifier_block generic_online_page_nb = {
+ .notifier_call = generic_online_page_notifier,
+ .priority = 0
+};
+
+static int __init init_online_page_chain(void)
+{
+ return register_online_page_notifier(&generic_online_page_nb);
+}
+pure_initcall(init_online_page_chain);
+
+static void online_page(struct page *page)
+{
+ raw_notifier_call_chain(&online_page_chain, 0, page);
+}
static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages,
void *arg)
--
1.5.6.5
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