[patch 2/2] mm, hotplug: protect zonelist building with zonelists_mutex

David Rientjes
2011-06-23T01:13:14Z

959ecc48fc75 ("mm/memory_hotplug.c: fix building of node hotplug
zonelist") does not protect the build_all_zonelists() call with
zonelists_mutex as needed. This can lead to races in constructing
zonelist ordering if a concurrent build is underway. Protecting this with
lock_memory_hotplug() is insufficient since zonelists can be rebuild
though sysfs as well.

Signed-off-by: David Rientjes <rientjes@google.com>
---
mm/memory_hotplug.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -498,7 +498,9 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid, u64 start)
* The node we allocated has no zone fallback lists. For avoiding
* to access not-initialized zonelist, build here.
*/
+ mutex_lock(&zonelists_mutex);
build_all_zonelists(NULL);
+ mutex_unlock(&zonelists_mutex);

return pgdat;
}