I'm running an eviction stress test with KFD and find that sometimes it
starts swapping. When that happens, swap usage goes up rapidly, but it
never comes down. Even after the processes terminate, and all VRAM and
GTT allocations are freed (checked in
/sys/kernel/debug/dri/0/amdgpu_{gtt|vram}_mm), swap space is still not
released.
Running the test repeatedly I was able to trigger the OOM killer quite
easily. The system died with a panic, running out of processes to kill.
The symptoms look like swap space is only allocated but never released.
A quick look at the swapping code in ttm_tt.c doesn't show any obvious
problems. I'm assuming that fput should free swap space. That should
happen when BOs are swapped back in, or destroyed. As far as I can tell,
amdgpu doesn't use persistent swap space, so I'm ignoring
TTM_PAGE_FLAG_PERSISTENT_SWAP.
Any other ideas or pointers?
Thanks,
 Felix
--
F e l i x K u e h l i n g
PMTS Software Development Engineer | Vertical Workstation/Compute
1 Commerce Valley Dr. East, Markham, ON L3T 7X6 Canada
(O) +1(289)695-1597
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