!6867 v2 nouveau: fix instmem race condition around ptr stores

Merge Pull Request from: @ci-robot 
 
PR sync from: Yipeng Zou <zouyipeng@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/HP4GZ3GDPNI7DFICE2OVSDUZARK4CJU6/ 
 
https://gitee.com/src-openeuler/kernel/issues/I9LK8M 
 
Link:https://gitee.com/openeuler/kernel/pulls/6867

 

Reviewed-by: Zhang Jianhua <chris.zjh@huawei.com>
Reviewed-by: Liu YongQiang <liuyongqiang13@huawei.com>
Signed-off-by: Zhang Changzhong <zhangchangzhong@huawei.com>