!7091 nouveau: lock the client object tree.

Merge Pull Request from: @ci-robot 
 
PR sync from: dinglongwei <dinglongwei1@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/2VMM6CRETSQCVPZVQN5MKTQYP2N4J2VC/ 
 
https://gitee.com/src-openeuler/kernel/issues/I9L9IX 
 
Link:https://gitee.com/openeuler/kernel/pulls/7091

 

Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Reviewed-by: Liu YongQiang <liuyongqiang13@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>