Re: drm: i915+fb: crtc->lock recursive locking deadlock on VT switch[>= 3.9-rc1 regresion]
From: Krzysztof Mazur
Date: Sun Apr 14 2013 - 02:47:15 EST
On Sat, Apr 13, 2013 at 06:10:40PM +0100, Chris Wilson wrote:
> On Sat, Apr 13, 2013 at 05:41:46PM +0200, Krzysztof Mazur wrote:
> > Hi,
> > the drm_fb_helper_hotplug_event() locks all crtc->mutex locks by calling
> > drm_modeset_lock_all() and later calls drm_fb_helper_probe_connector_modes(),
> > which in case of i915 DRM driver effectively calls
> > intel_get_load_detect_pipe() that tries to lock crtc->mutex again.
> > This causes a deadlock, and can be in some cases triggered by VT
> > switch to framebuffer console on i915.
> > This bug is introduced in Linux 3.9-rc1 and still exists
> > in v3.9-rc6-183-gbf81710. Linux 3.8 is ok.
> In Dave's drm-fixes branch:
> commit 89ced125472b8551c65526934b7f6c733a6864fa
> Author: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Date: Thu Apr 11 14:26:55 2013 +0000
> drm/fb-helper: Fix locking in drm_fb_helper_hotplug_event
Yes, this patch fixes the problem.
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