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authorKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>2011-01-11 16:44:01 +0900
committerPekka Enberg <penberg@kernel.org>2011-01-11 17:09:50 +0200
commit925268a06dc2b1ff7bfcc37419a6827a0e739639 (patch)
treec0a5b3a6dc8ea6c4ea8e469e58223877f52c2e5b
parent3c0eee3fe6a3a1c745379547c7e7c904aa64f6d5 (diff)
memory hotplug: one more lock on memory hotplug
Now, memory_hotplug_(un)lock() is used for add/remove/offline pages for avoiding races with hibernation. But this should be held in online_pages(), too. It seems asymmetric. There are cases where one has to avoid a race with memory hotplug notifier and his own local code, and hotplug v.s. hotplug. This will add a generic solution for avoiding races. In other view, having lock here has no big impacts. online pages is tend to be done by udev script at el against each memory section one by one. Then, it's better to have lock here, too. Cc: <stable@kernel.org> # 2.6.37 Reviewed-by: Christoph Lameter <cl@linux.com> Acked-by: David Rientjes <rientjes@google.com> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Pekka Enberg <penberg@kernel.org>
-rw-r--r--include/linux/memory_hotplug.h6
-rw-r--r--mm/memory_hotplug.c4
2 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
index 31c237a00c48..12b9eb5a36c3 100644
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -161,6 +161,12 @@ extern void register_page_bootmem_info_node(struct pglist_data *pgdat);
extern void put_page_bootmem(struct page *page);
#endif
+/*
+ * Lock for memory hotplug guarantees 1) all callbacks for memory hotplug
+ * notifier will be called under this. 2) offline/online/add/remove memory
+ * will not run simultaneously.
+ */
+
void lock_memory_hotplug(void);
void unlock_memory_hotplug(void);
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 2c6523af5473..83163c096a75 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -407,6 +407,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
int ret;
struct memory_notify arg;
+ lock_memory_hotplug();
arg.start_pfn = pfn;
arg.nr_pages = nr_pages;
arg.status_change_nid = -1;
@@ -419,6 +420,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
ret = notifier_to_errno(ret);
if (ret) {
memory_notify(MEM_CANCEL_ONLINE, &arg);
+ unlock_memory_hotplug();
return ret;
}
/*
@@ -443,6 +445,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
printk(KERN_DEBUG "online_pages %lx at %lx failed\n",
nr_pages, pfn);
memory_notify(MEM_CANCEL_ONLINE, &arg);
+ unlock_memory_hotplug();
return ret;
}
@@ -467,6 +470,7 @@ int online_pages(unsigned long pfn, unsigned long nr_pages)
if (onlined_pages)
memory_notify(MEM_ONLINE, &arg);
+ unlock_memory_hotplug();
return 0;
}

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