From: Chris Wilson chris@chris-wilson.co.uk
commit 20612303a0b45de748d31331407e84300c38e497 upstream.
(NOTE: This is the minimal backportable fix, a full fix is being developed at https://patchwork.freedesktop.org/patch/388048/)
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+ Reviewed-by: Matthew Auld matthew.auld@intel.com Link: https://patchwork.freedesktop.org/patch/msgid/20200728152144.1100-1-chris@ch... Signed-off-by: Rodrigo Vivi rodrigo.vivi@intel.com [Joonas: Rebased and reordered into drm-intel-gt-next branch] [Joonas: Added a note and link about more complete fix] Signed-off-by: Joonas Lahtinen joonas.lahtinen@linux.intel.com (cherry picked from commit f4b3c395540aa3d4f5a6275c5bdd83ab89034806) Signed-off-by: Jani Nikula jani.nikula@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/gpu/drm/i915/i915_sw_fence.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/i915/i915_sw_fence.c +++ b/drivers/gpu/drm/i915/i915_sw_fence.c @@ -158,9 +158,13 @@ static void __i915_sw_fence_wake_up_all(
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))