My laptop freezes while copying data. For example when I copy 5GB data from my local drive to an external hard drive, my laptop becomes completely unresponsive until the copying is finished. I am very familiar with this issue, I experienced it several years ago when I was still using Gentoo. The problem is very well described here (including all symptoms): https://forums.opensuse.org/showthre...e-copying-data

I know it's a kernel related problem and it has something to do with dirty ratio and cache size... But I don't know what to do, how to fix it. Is it a kernel bug? Should I report it somewhere?

Everything worked fine in the previous versions of OpenSuse, it started when I upgraded to OpenSuse 13.1. I'm running desktop kernel 3.12.8 from the OpenSuse Standard Kernel repo (the original kernel shipped with 13.1 doesn't support my laptop).