!2811 [sync] PR-2716: ext4: recheck buffer valid after page unlock

Merge Pull Request from: @openeuler-sync-bot 
 

Origin pull request: 
https://gitee.com/openeuler/kernel/pulls/2716 
 
PR sync from: yangerkun <yangerkun@huawei.com>
https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/KM5ZGQQVCMZJORVBS7ZBCITFCOIN7S7L/ 
 
https://gitee.com/openeuler/kernel/issues/I8BBWH 
 
Link:https://gitee.com/openeuler/kernel/pulls/2811

 

Reviewed-by: zhangyi (F) <yi.zhang@huawei.com>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>