Using the latest GIT version, branch 5.7. I am able to set an HTTP cache limit to 10 Mb using QWebEngineProfile. On my desktop KUbuntu the value works fine. When QtWebEngine starts to play a DRM video, it caches small pieces of data in ~/.cache/webeng5/, not exceeding the limit of 10 Mb. However on another system (Ubuntu 14.04, X11+openbox) I see that the same application with the same binary QtWebEngine library (copied from the system #1) ignores the cache limit. It starts to cache more aggressively and very soon exceeds the limit. On some HTML demos the application caches about 50 Mb and crashes with SIGBUS because there is no free space in HOME (total size of HOME is 50 Mb). It looks like that QtWebEngine cannot apply the cache limit value for some reason. Possibly it depends on some system package that is used in runtime. This may explain why it works on the system #1 and doesn't work on the system #2. The sample code is attached.

Steps to reproduce:

1) Compile the sample app
2) Run as follows:

./webeng5 https://shaka-player-demo.appspot.com

3) Select "Sintel (4k) - Widevine" from the list and click "Load stream"
4) Observe the size of ~/.cache/webeng5. It may increase and exceed 10 Mb soon. With https://shaka-player-demo.appspot.com/ the demo consumes all the free space available in HOME and sometimes continues to play, and sometimes crashes with "Bus error".

I can provide any information to help solving the issue.