blkio: deletion of a cgroup was causes oops

o Now a cgroup list of blkg elements can contain blkg from multiple policies.
  Before sending an unlink event, make sure blkg belongs to they policy. If
  policy does not own the blkg, do not send update for this blkg.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 86e7066a0b62ebe58b0c778ff3578d290b677e9b..b06ca70354e30d9131550fc898cf0970e541b6a3 100644 (file)
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -1411,13 +1411,14 @@ static void blkiocg_destroy(struct cgroup_subsys *subsys, struct cgroup *cgroup)
                /*
                 * This blkio_group is being unlinked as associated cgroup is
                 * going away. Let all the IO controlling policies know about
-                * this event. Currently this is static call to one io
-                * controlling policy. Once we have more policies in place, we
-                * need some dynamic registration of callback function.
+                * this event.
                 */
                spin_lock(&blkio_list_lock);
-               list_for_each_entry(blkiop, &blkio_list, list)
+               list_for_each_entry(blkiop, &blkio_list, list) {
+                       if (blkiop->plid != blkg->plid)
+                               continue;
                        blkiop->ops.blkio_unlink_group_fn(key, blkg);
+               }
                spin_unlock(&blkio_list_lock);
        } while (1);