There are many different error-logs for the same issue, they contain plasmashell too, I do not think the plasmashell is fault, but browser with AMD driver is.
See my first error log today:
Nov 15 08:16:52 zesko kernel: [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring vcn_dec timeout, signaled seq=6534, emitted seq=6536
Nov 15 08:16:52 zesko kernel: [drm:amdgpu_job_timedout [amdgpu]] *ERROR* Process information: process vivaldi-bin pid 2019 thread vivaldi-bi:cs0 pid 2069
Nov 15 08:17:00 zesko kernel: [drm:amdgpu_cs_ioctl [amdgpu]] *ERROR* Failed to initialize parser -125!
Nov 15 08:17:00 zesko kernel: [drm:amdgpu_cs_ioctl [amdgpu]] *ERROR* Failed to initialize parser -125!
Nov 15 08:17:00 zesko kernel: amdgpu 0000:09:00.0: amdgpu: [gfxhub] page fault (src_id:0 ring:221 vmid:6 pasid:32771, for process plasmashell pid 1228 thread plasmashel:cs0 pid 1293)
Nov 15 08:17:00 zesko kernel: amdgpu 0000:09:00.0: amdgpu: in page starting at address 0x0000800000000000 from client 0x1b (UTCL2)
my second error-log today:
Nov 15 08:27:50 zesko kernel: [drm:amdgpu_dm_atomic_commit_tail [amdgpu]] *ERROR* Waiting for fences timed out!
Nov 15 08:27:55 zesko kernel: [drm:amdgpu_dm_atomic_commit_tail [amdgpu]] *ERROR* Waiting for fences timed out!
Nov 15 08:27:55 zesko kernel: [drm:amdgpu_job_timedout [amdgpu]] *ERROR* ring gfx_0.0.0 timeout, signaled seq=235399, emitted seq=235401
Nov 15 08:27:55 zesko kernel: [drm:amdgpu_job_timedout [amdgpu]] *ERROR* Process information: process vivaldi-bin pid 1862 thread vivaldi-bi:cs0 pid 1907
Nov 15 08:27:59 zesko kernel: amdgpu 0000:09:00.0: [drm:amdgpu_ring_test_helper [amdgpu]] *ERROR* ring kiq_2.1.0 test failed (-110)
Nov 15 08:27:59 zesko kernel: [drm:gfx_v10_0_hw_fini [amdgpu]] *ERROR* KGQ disable failed
Nov 15 08:27:59 zesko kernel: amdgpu 0000:09:00.0: [drm:amdgpu_ring_test_helper [amdgpu]] *ERROR* ring kiq_2.1.0 test failed (-110)
Nov 15 08:27:59 zesko kernel: [drm:gfx_v10_0_hw_fini [amdgpu]] *ERROR* KCQ disable failed
Nov 15 08:28:00 zesko kernel: [drm:gfx_v10_0_hw_fini [amdgpu]] *ERROR* failed to halt cp gfx
Nov 15 08:28:03 zesko kernel: [drm:amdgpu_cs_ioctl [amdgpu]] *ERROR* Failed to initialize parser -125!
Nov 15 08:28:03 zesko kernel: [drm:amdgpu_cs_ioctl [amdgpu]] *ERROR* Failed to initialize parser -125!
Nov 15 08:28:03 zesko kernel: [drm:amdgpu_cs_ioctl [amdgpu]] *ERROR* Failed to initialize parser -125!
Nov 15 08:28:03 zesko kernel: amdgpu 0000:09:00.0: amdgpu: [gfxhub] page fault (src_id:0 ring:221 vmid:5 pasid:32771, for process plasmashell pid 1236 thread plasmashel:cs0 pid 1301)
Nov 15 08:28:03 zesko kernel: amdgpu 0000:09:00.0: amdgpu: in page starting at address 0x0000800000030000 from client 0x1b (UTCL2)
You can see that is why both logs are different.
I am waiting for Linux Kernel 5.16 for this bug fix.