A long time ago (months? over a year?), I used to have this issue where mesa
would cause the system to leak memory over time by just idling or browsing the
web (kde, firefox) and at some point (just hours) it'd be bad enough (on 8GB
RAM) that over 4GB swap would be used and system would be really slow because
of that.
Sorting processes by ram usage (on eg: top) would show no culprits; the memory
was being leaked kernelside. Not even restarting X would fix the problem: A
reboot was always necessary.
The issue disappeared once I started building mesa with LLVM support... until
now.
10.1.2 disables LLVM for RV770, which among other things fixes games such as
DOTA2, but the problem is suddenly back, making me pretty sure it's linked to
not using LLVM's shader compiler (or same thing, has to do with how shaders are
compiled without LLVM).