Quoting Christian König (2020-03-30 13:34:25)
This reverts commit 7be1b9b8e9d1e9ef0342d2e001f44eec4030aa4d.
The drm_mm is supposed to work in atomic context, so calling schedule() or in this case cond_resched() is illegal.
https://patchwork.freedesktop.org/patch/358535/?series=74984&rev=1
(Though I do question the wisdom in searching, rather than just doing a cursory check, from an atomic context :) -Chris