8a6543ba47
We have a struct_mutex deadlock during driver init on ILK [ 54.320273] ============================================= [ 54.320371] [ INFO: possible recursive locking detected ] [ 54.320471] 3.15.0-rc2-flip_race+ #2 Not tainted [ 54.320567] --------------------------------------------- [ 54.320665] modprobe/2178 is trying to acquire lock: [ 54.320762] (&dev->struct_mutex){+.+.+.}, at: [<ffffffffa0568b05>] intel_enable_gt_powersave+0xa5/0x9d0 [i915] [ 54.321111] [ 54.321111] but task is already holding lock: [ 54.321250] (&dev->struct_mutex){+.+.+.}, at: [<ffffffffa05b4c2e>] intel_modeset_init_hw+0x3e/0x60 [i915] [ 54.321583] [ 54.321583] other info that might help us debug this: [ 54.321724] Possible unsafe locking scenario: [ 54.321724] [ 54.321863] CPU0 [ 54.321954] ---- [ 54.322046] lock(&dev->struct_mutex); [ 54.322221] lock(&dev->struct_mutex); [ 54.322397] [ 54.322397] *** DEADLOCK *** [ 54.322397] [ 54.322638] May be due to missing lock nesting notation [ 54.322638] [ 54.322781] 4 locks held by modprobe/2178: [ 54.322875] #0: (&dev->mutex){......}, at: [<ffffffff813592eb>] __driver_attach+0x5b/0xb0 [ 54.323230] #1: (&dev->mutex){......}, at: [<ffffffff813592f9>] __driver_attach+0x69/0xb0 [ 54.323582] #2: (drm_global_mutex){+.+.+.}, at: [<ffffffffa04e1e0d>] drm_dev_register+0x2d/0x120 [drm] [ 54.323945] #3: (&dev->struct_mutex){+.+.+.}, at: [<ffffffffa05b4c2e>] intel_modeset_init_hw+0x3e/0x60 [i915] This regression got introduced in: commit 586d5270b60dc1f35cc3ca982d403765bad77965 Author: Imre Deak <imre.deak@intel.com> Date: Mon Apr 14 20:24:28 2014 +0300 drm/i915: move getting struct_mutex lower in the callstack during GPU reset Fix the problem by not taking struct_mutex around intel_enable_gt_powersave() in intel_modeset_init_hw() since intel_enable_gt_powersave() now grabs the mutex itself. Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch> |
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