mem-hotplug: introduce {un}lock_memory_hotplug()

Presently hwpoison is using lock_system_sleep() to prevent a race with
memory hotplug.  However lock_system_sleep() is a no-op if
CONFIG_HIBERNATION=n.  Therefore we need a new lock.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Suggested-by: Hugh Dickins <hughd@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 4307231..31c237a 100644 (file)
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -161,6 +161,9 @@ extern void register_page_bootmem_info_node(struct pglist_data *pgdat);
 extern void put_page_bootmem(struct page *page);
 #endif
 
+void lock_memory_hotplug(void);
+void unlock_memory_hotplug(void);
+
 #else /* ! CONFIG_MEMORY_HOTPLUG */
 /*
  * Stub functions for when hotplug is off
@@ -192,6 +195,9 @@ static inline void register_page_bootmem_info_node(struct pglist_data *pgdat)
 {
 }
 
+static inline void lock_memory_hotplug(void) {}
+static inline void unlock_memory_hotplug(void) {}
+
 #endif /* ! CONFIG_MEMORY_HOTPLUG */
 
 #ifdef CONFIG_MEMORY_HOTREMOVE

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 1243241..46ab2c0 100644 (file)
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -51,6 +51,7 @@
 #include <linux/slab.h>
 #include <linux/swapops.h>
 #include <linux/hugetlb.h>
+#include <linux/memory_hotplug.h>
 #include "internal.h"
 
 int sysctl_memory_failure_early_kill __read_mostly = 0;
@@ -1230,11 +1231,10 @@ static int get_any_page(struct page *p, unsigned long pfn, int flags)
                return 1;
 
        /*
-        * The lock_system_sleep prevents a race with memory hotplug,
-        * because the isolation assumes there's only a single user.
+        * The lock_memory_hotplug prevents a race with memory hotplug.
         * This is a big hammer, a better would be nicer.
         */
-       lock_system_sleep();
+       lock_memory_hotplug();
 
        /*
         * Isolate the page, so that it doesn't get reallocated if it
@@ -1264,7 +1264,7 @@ static int get_any_page(struct page *p, unsigned long pfn, int flags)
                ret = 1;
        }
        unset_migratetype_isolate(p);
-       unlock_system_sleep();
+       unlock_memory_hotplug();
        return ret;
 }
 

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 9260314..2c6523a 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -34,6 +34,23 @@
 
 #include "internal.h"
 
+DEFINE_MUTEX(mem_hotplug_mutex);
+
+void lock_memory_hotplug(void)
+{
+       mutex_lock(&mem_hotplug_mutex);
+
+       /* for exclusive hibernation if CONFIG_HIBERNATION=y */
+       lock_system_sleep();
+}
+
+void unlock_memory_hotplug(void)
+{
+       unlock_system_sleep();
+       mutex_unlock(&mem_hotplug_mutex);
+}
+
+
 /* add this memory to iomem resource */
 static struct resource *register_memory_resource(u64 start, u64 size)
 {
@@ -493,7 +510,7 @@ int mem_online_node(int nid)
        pg_data_t       *pgdat;
        int     ret;
 
-       lock_system_sleep();
+       lock_memory_hotplug();
        pgdat = hotadd_new_pgdat(nid, 0);
        if (pgdat) {
                ret = -ENOMEM;
@@ -504,7 +521,7 @@ int mem_online_node(int nid)
        BUG_ON(ret);
 
 out:
-       unlock_system_sleep();
+       unlock_memory_hotplug();
        return ret;
 }
 
@@ -516,7 +533,7 @@ int __ref add_memory(int nid, u64 start, u64 size)
        struct resource *res;
        int ret;
 
-       lock_system_sleep();
+       lock_memory_hotplug();
 
        res = register_memory_resource(start, size);
        ret = -EEXIST;
@@ -563,7 +580,7 @@ error:
                release_memory_resource(res);
 
 out:
-       unlock_system_sleep();
+       unlock_memory_hotplug();
        return ret;
 }
 EXPORT_SYMBOL_GPL(add_memory);
@@ -791,7 +808,7 @@ static int offline_pages(unsigned long start_pfn,
        if (!test_pages_in_a_zone(start_pfn, end_pfn))
                return -EINVAL;
 
-       lock_system_sleep();
+       lock_memory_hotplug();
 
        zone = page_zone(pfn_to_page(start_pfn));
        node = zone_to_nid(zone);
@@ -880,7 +897,7 @@ repeat:
        writeback_set_ratelimit();
 
        memory_notify(MEM_OFFLINE, &arg);
-       unlock_system_sleep();
+       unlock_memory_hotplug();
        return 0;
 
 failed_removal:
@@ -891,7 +908,7 @@ failed_removal:
        undo_isolate_page_range(start_pfn, end_pfn);
 
 out:
-       unlock_system_sleep();
+       unlock_memory_hotplug();
        return ret;
 }