It will loss a large number of blocks when I reboot the geth

[ptr66]

Geth version: 1.1.1-stable
OS & Version: Linux

Hi, It will loss a large number of blocks when I reboot the geth. Like this（I catch the state of syncing after reboot）：

eth.syncing
{
currentBlock: 7881263,
highestBlock: 7970698,
knownStates: 190833495,
pulledStates: 190833495,
startingBlock: 7970681
}

I think the 'startingBlock' is right, it is the block number where the moment I kill the geth process, but the 'currentBlock' is wrong, and I find the problem also exist in old geth version. How can I repair this problem？ Thank you！

[wangsai-silence]

Do not use kill -9. Use kill -15