[Why] In multi-monitor scenario, if first crtc's flip done event occurs delayed (but within timeout), due to non-blocking design of commit_tail(), there are more than one commit's scheduled by the time the second crtc's wait_for_completion_timeout() is called in drm_atomic_helper_wait_for_flip_done. Due to these in-between additions and deletions in the atomic state, it is found that the system fails while accessing common data structures of the second crtc in drm_atomic_helper_wait_for_flip_done(), leading to crash as below: BUG: unable to handle kernel paging request at 000000010000001c IP: do_raw_spin_lock+0xf/0x94 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI Call Trace: __wait_for_common+0x36/0x60 drm_atomic_helper_wait_for_flip_done+0x47/0x89 amdgpu_dm_atomic_commit_tail+0xf4b/0xf84 ? drm_atomic_helper_wait_for_dependencies+0x1cd/0x217 commit_tail+0x41/0x5f [How] Move drm_atomic_helper_commit_hw_done() post wait_for_flip_done(), which cleans up the atomic state's commit and completes pending hw_done and flip_done works as a result there wont be dangling flip waits on random commits. Signed-off-by: Shirish S <shirish.s@xxxxxxx> --- drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c index 0f10d92..41a1958 100644 --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c @@ -4626,12 +4626,17 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state) } spin_unlock_irqrestore(&adev->ddev->event_lock, flags); - /* Signal HW programming completion */ - drm_atomic_helper_commit_hw_done(state); if (wait_for_vblank) drm_atomic_helper_wait_for_flip_done(dev, state); + /* Atomic state pointer gets corrupted in case of frequent + * modesets operations like changing resolutions. + * Hence discard state->commit before signalling to user + * space. + */ + drm_atomic_helper_commit_hw_done(state); + drm_atomic_helper_cleanup_planes(dev, state); /* -- 2.7.4 _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
