Quoting Daniel Vetter (2020-03-31 11:38:50)
On Tue, Mar 31, 2020 at 11:20 AM Chris Wilson chris@chris-wilson.co.uk wrote:
Quoting Daniel Vetter (2020-03-31 10:16:18)
On Tue, Mar 31, 2020 at 10:59:45AM +0200, Christian König wrote:
A not so gentle ping, since this pretty much broke all TTM based drivers.
Could we revert this for now?
Always ack for revert.
Acked-by: Daniel Vetter daniel.vetter@ffwll.ch
So you didn't check the earlier patch either?
I did, but wasn't super sold on the idea of more flags to smack an r-b onto it, so figured I'll throw the default ack-for-revert on this meanwhile.
We allow userspace to poison the drm_mm at roughly 8K intervals, a search space of 35b with typically O(N^2) behaviour and each node traversal (rb_next/rb_prev) will itself be costly. Even our simple tests can generate a search of several minutes before our patience runs out.o Any drm_mm that allows for userspace to control alignment can be arbitrarily fragmented, hence a raised eyebrow that this search would be allowed in atomic context. -Chris