mm, hotplug: protect zonelist building with zonelists_mutex

Commit 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> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm, hotplug: protect zonelist building with zonelists_mutex
Commit 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> Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
David Rientjes · Linus Torvalds
1 parent 7553e8f2d5
Showing 1 changed file with 2 additions and 0 deletions Side-by-side Diff
mm/memory_hotplug.c
@@ -498,7 +498,9 @@
 	 * 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;
 }
...	...	@@ -498,7 +498,9 @@
498	498	* The node we allocated has no zone fallback lists. For avoiding
499	499	* to access not-initialized zonelist, build here.
500	500	*/
	501	+ mutex_lock(&zonelists_mutex);
501	502	build_all_zonelists(NULL);
	503	+ mutex_unlock(&zonelists_mutex);
502	504
503	505	return pgdat;
504	506	}