The flags passed to the wait_entry.func are passed onwards to try_to_wake_up(), which has a very particular interpretation for its wake_flags. In particular, beyond the published WF_SYNC, it has a few internal flags as well. Since we passed the fence->error down the chain via the flags argument, these ended up in the default_wake_function confusing the kernel/sched.

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/2110 Fixes: ef4688497512 ("drm/i915: Propagate fence errors") Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Matthew Auld matthew.auld@intel.com Cc: stable@vger.kernel.org # v5.4+ --- drivers/gpu/drm/i915/i915_sw_fence.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_sw_fence.c b/drivers/gpu/drm/i915/i915_sw_fence.c index 295b9829e2da..4cd2038cbe35 100644 --- a/drivers/gpu/drm/i915/i915_sw_fence.c +++ b/drivers/gpu/drm/i915/i915_sw_fence.c @@ -164,9 +164,13 @@ static void __i915_sw_fence_wake_up_all(struct i915_sw_fence *fence,

do { list_for_each_entry_safe(pos, next, &x->head, entry) { - pos->func(pos, - TASK_NORMAL, fence->error, - &extra); + int wake_flags; + + wake_flags = fence->error; + if (pos->func == autoremove_wake_function) + wake_flags = 0; + + pos->func(pos, TASK_NORMAL, wake_flags, &extra); }

if (list_empty(&extra))