cpu_up() has #ifdef CONFIG_MEMORY_HOTPLUG code blocks, which
call mem_online_node() to put its node online if offlined and
then call build_all_zonelists() to initialize the zone list.
These steps are specific to memory hotplug, and should be
managed in mm/memory_hotplug.c. lock_memory_hotplug() should
also be held for the whole steps.
For this reason, this patch replaces mem_online_node() with
try_online_node(), which performs the whole steps with
lock_memory_hotplug() held. try_online_node() is named after
try_offline_node() as they have similar purpose.
There is no functional change in this patch.
Signed-off-by: Toshi Kani <toshi.kani@xxxxxx>
---
v2: Added pr_err() in case of NULL pgdat in try_online_node().
---
include/linux/memory_hotplug.h | 8 +++++++-
kernel/cpu.c | 29 +++--------------------------
mm/memory_hotplug.c | 16 ++++++++++++++--
3 files changed, 24 insertions(+), 29 deletions(-)
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index dd38e62..22203c2 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -94,6 +94,8 @@ extern void __online_page_set_limits(struct page *page);
extern void __online_page_increment_counters(struct page *page);
extern void __online_page_free(struct page *page);
+extern int try_online_node(int nid);
+
#ifdef CONFIG_MEMORY_HOTREMOVE
extern bool is_pageblock_removable_nolock(struct page *page);
extern int arch_remove_memory(u64 start, u64 size);
@@ -225,6 +227,11 @@ static inline void register_page_bootmem_info_node(struct pglist_data *pgdat)
{
}
+static inline int try_online_node(int nid)
+{
+ return 0;
+}
+
static inline void lock_memory_hotplug(void) {}
static inline void unlock_memory_hotplug(void) {}
@@ -256,7 +263,6 @@ static inline void remove_memory(int nid, u64 start, u64 size) {}
extern int walk_memory_range(unsigned long start_pfn, unsigned long end_pfn,
void *arg, int (*func)(struct memory_block *, void *));
-extern int mem_online_node(int nid);
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);
diff --git a/kernel/cpu.c b/kernel/cpu.c
index d7f07a2..c10b285 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -420,11 +420,6 @@ int cpu_up(unsigned int cpu)
{
int err = 0;
-#ifdef CONFIG_MEMORY_HOTPLUG
- int nid;
- pg_data_t *pgdat;
-#endif
-
if (!cpu_possible(cpu)) {
printk(KERN_ERR "can't online cpu %d because it is not "
"configured as may-hotadd at boot time\n", cpu);
@@ -435,27 +430,9 @@ int cpu_up(unsigned int cpu)
return -EINVAL;
}
-#ifdef CONFIG_MEMORY_HOTPLUG
- nid = cpu_to_node(cpu);
- if (!node_online(nid)) {
- err = mem_online_node(nid);
- if (err)
- return err;
- }
-
- pgdat = NODE_DATA(nid);
- if (!pgdat) {
- printk(KERN_ERR
- "Can't online cpu %d due to NULL pgdat\n", cpu);
- return -ENOMEM;
- }
-
- if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
- mutex_lock(&zonelists_mutex);
- build_all_zonelists(NULL, NULL);
- mutex_unlock(&zonelists_mutex);
- }
-#endif
+ err = try_online_node(cpu_to_node(cpu));
+ if (err)
+ return err;
cpu_maps_update_begin();
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index ed85fe3..d6fc915 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1044,17 +1044,23 @@ static void rollback_node_hotadd(int nid, pg_data_t *pgdat)
}
-/*
+/**
+ * try_online_node - online a node if offlined
+ *
* called by cpu_up() to online a node without onlined memory.
*/
-int mem_online_node(int nid)
+int try_online_node(int nid)
{
pg_data_t *pgdat;
int ret;
+ if (node_online(nid))
+ return 0;
+
lock_memory_hotplug();
pgdat = hotadd_new_pgdat(nid, 0);
if (!pgdat) {
+ pr_err("Cannot online node %d due to NULL pgdat\n", nid);
ret = -ENOMEM;
goto out;
}
@@ -1062,6 +1068,12 @@ int mem_online_node(int nid)
ret = register_one_node(nid);
BUG_ON(ret);
+ if (pgdat->node_zonelists->_zonerefs->zone == NULL) {
+ mutex_lock(&zonelists_mutex);
+ build_all_zonelists(NULL, NULL);
+ mutex_unlock(&zonelists_mutex);
+ }
+
out:
unlock_memory_hotplug();
return ret;
--
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