fedora 10 新内核升级问题

用yum upgrade命令升级，郁闷，提示如下错误

Package Arch Version Repository Size
================================================================================
Installing:
kernel x86_64 2.6.27.19-170.2.35.fc10 updates 20 M
kernel-devel x86_64 2.6.27.19-170.2.35.fc10 updates 5.5 M

Transaction Summary
================================================================================
Install 2 Package(s)
Update 0 Package(s)
Remove 0 Package(s)

Total size: 25 M
Is this ok [y/N]: y
Downloading Packages:
Running rpm_check_debug
Running Transaction Test
Finished Transaction Test


Transaction Check Error:
installing package kernel-2.6.27.19-170.2.35.fc10.x86_64 needs 6MB on the / filesystem
installing package kernel-devel-2.6.27.19-170.2.35.fc10.x86_64 needs 6MB on the / filesystem

Error Summary
-------------
Disk Requirements:
At least 6MB needed on the / filesystem.

我的 / 目录下还有71M的空间为什么还提示出错？