0000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 DR6: ffff0ff0 DR7: 00000400 Process X (pid: 2866, ti=f51d6000 task=f61af8d0 task.ti=f51d6000) Stack: 00000001 00000000 f5835414 f51d7e84 f5835400 f54f85c0 f51d7f10 c12b530b 00000001 c151b139 c14751b6 c152e030 00000b32 00006459 00000059 0000e200 00000001 00000000 00006459 c159ddd0 c12dc1a0 ffffffea 00000000 00000000 Call Trace: [] drm_ioctl+0x2eb/0x440 [] ? i915_gem_init+0xe0/0xe0 [] ? enqueue_hrtimer+0x1b/0x50 [] ? __hrtimer_start_range_ns+0x161/0x330 [] ? lock_hrtimer_base+0x23/0x50 [] ? hrtimer_try_to_cancel+0x33/0x70 [] ? drm_version+0x90/0x90 [] vfs_ioctl+0x31/0x50 [] do_vfs_ioctl+0x64/0x510 [] ? hrtimer_nanosleep+0x8e/0x100 [] ? update_rmtp+0x80/0x80 [] sys_ioctl+0x39/0x60 [] syscall_call+0x7/0xb Code: 83 c4 0c 5b 5e 5f 5d c3 c7 44 24 04 2c 05 53 c1 c7 04 24 6f ef 47 c1 e8 6e e0 fd ff c7 83 38 1e 00 00 00 00 00 00 e9 3f ff ff +ff <0f> 0b eb fe 0f 0b eb fe 8d b4 26 00 00 00 00 0f 0b eb fe 8d b6 EIP: [] i915_gem_entervt_ioctl+0xf1/0x110 SS:ESP 0068:f51d7e20 ---[ end trace dd332ec083cbd513 ]--- The crash happens here in i915_gem_entervt_ioctl() : 3659 BUG_ON(!list_empty(&dev_priv->mm.active_list)); 3660 BUG_ON(!list_empty(&dev_priv->mm.flushing_list)); -> 3661 BUG_ON(!list_empty(&dev_priv->mm.inactive_list)); 3662 mutex_unlock(&dev->struct_mutex); Quoting Chris : "That BUG_ON there is silly and can simply be removed. The check is to verify that no batches were submitted to the kernel whilst the UMS/GEM client was suspended - to which the BUG_ONs are a crude approximation. Furthermore, the checks are too late, since it means we attempted to program the hardware whilst it was in an invalid state, the BUG_ONs are the least of your concerns at that point." Note that this regression has been introduced in commit 1b50247a8ddde4af5aaa0e6bc125615372ce6c16 Author: Chris Wilson Date: Tue Apr 24 15:47:30 2012 +0100 drm/i915: Remove the list of pinned inactive objects Cc: Chris Wilson Signed-off-by: Willy Tarreau [danvet: Added note about the regressing commit and cc: stable.] Cc: stable@vger.kernel.org Signed-off-by: Daniel Vetter