Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

suppose when execute job we return the remaining storage capacity of TiKV(%s) is less than 10%%, the context will be cancelled

then here we noticed that context cancelled and return context cancelled error(might be wrapped inside other error, such as rpc error: code = Canceled desc = context canceled: [BR:PD:ErrPDBatchScanRegion]batch scan region" during page scan regions)

and in here, we record this context cancelled err, not the err that causes context cancel is eaten

2. What did you expect to see? (Required)

3. What did you see instead (Required)

4. What is your TiDB version? (Required)

master