Through a twisty and circuituous path it is possible to currently trick the code into creating a default context and forgetting to pin it immediately into the GGTT. (This requires a system using contexts without an aliasing ppgtt, which is currently restricted to Baytrails machines manually specifying a module parameter to force enable contexts.) The consequence is that during module unload we attempt to unpin the default context twice and encounter a BUG remonstrating that we attempt to unpin an unbound object. [ 161.002869] Kernel BUG at f84861f8 [verbose debug info unavailable] [ 161.002875] invalid opcode: 0000 [#1] SMP [ 161.002882] Modules linked in: coretemp kvm_intel kvm crc32_pclmul aesni_intel aes_i586 xts lrw gf128mul ablk_helper cryptd hid_sensor_accel_3d hid_sensor_gyro_3d hid_sensor_magn_3d hid_sensor_trigger industrialio_triggered_buffer kfifo_buf industrialio hid_sensor_iio_common snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_page_alloc snd_seq_midi snd_seq_midi_event dm_multipath scsi_dh asix ppdev usbnet snd_rawmidi mii hid_sensor_hub microcode snd_seq rfcomm bnep snd_seq_device bluetooth snd_timer snd parport_pc binfmt_misc soundcore dw_dmac_pci dw_dmac_core mac_hid lp parport dm_mirror dm_region_hash dm_log hid_generic usbhid hid i915(O-) drm_kms_helper(O) igb dca ptp pps_core i2c_algo_bit drm(O) ahci libahci video [ 161.002991] CPU: 0 PID: 2114 Comm: rmmod Tainted: G W O 3.13.0-rc8+ #2 [ 161.002997] Hardware name: NEXCOM VTC1010/Aptio CRB, BIOS 5.6.5 09/24/2013 [ 161.003004] task: dbdd6800 ti: dbe0e000 task.ti: dbe0e000 [ 161.003010] EIP: 0060:[<f84861f8>] EFLAGS: 00010246 CPU: 0 [ 161.003044] EIP is at i915_gem_object_ggtt_unpin+0x88/0x90 [i915] [ 161.003050] EAX: dfce3840 EBX: 00000000 ECX: dfafd690 EDX: dfce3874 [ 161.003056] ESI: c0086b40 EDI: df962e00 EBP: dbe0fe1c ESP: dbe0fe0c [ 161.003062] DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 [ 161.003068] CR0: 8005003b CR2: b7718000 CR3: 1bec0000 CR4: 001007f0 [ 161.003076] Stack: [ 161.003081] 00afc014 00000004 c0086b40 dfafc000 dbe0fe38 f8487e5a dfaa5400 c0086b40 [ 161.003099] dfafc000 dfaa5400 dfaa5414 dbe0fe58 f84741aa 00000000 f89c34b9 dfaa5414 [ 161.003117] dfaa5400 dfaa5400 f644b000 dbe0fe6c f89a5443 dfaa5400 f8505000 f644b000 [ 161.003134] Call Trace: [ 161.003169] [<f8487e5a>] i915_gem_context_fini+0xba/0x1c0 [i915] [ 161.003202] [<f84741aa>] i915_driver_unload+0x1fa/0x2f0 [i915] [ 161.003232] [<f89a5443>] drm_dev_unregister+0x23/0x90 [drm] [ 161.003259] [<f89a54ed>] drm_put_dev+0x3d/0x70 [drm] [ 161.003294] [<f8470615>] i915_pci_remove+0x15/0x20 [i915] [ 161.003306] [<c1338a6f>] pci_device_remove+0x2f/0xa0 [ 161.003317] [<c140c871>] __device_release_driver+0x61/0xc0 [ 161.003328] [<c140d12f>] driver_detach+0x8f/0xa0 [ 161.003341] [<c140c54f>] bus_remove_driver+0x4f/0xc0 [ 161.003353] [<c140d708>] driver_unregister+0x28/0x60 [ 161.003362] [<c10cee42>] ? stop_cpus+0x32/0x40 [ 161.003372] [<c10bd510>] ? module_refcount+0x90/0x90 [ 161.003383] [<c13378c5>] pci_unregister_driver+0x15/0x60 [ 161.003413] [<f89a739f>] drm_pci_exit+0x9f/0xb0 [drm] [ 161.003458] [<f84e624a>] i915_exit+0x1b/0x1d [i915] [ 161.003468] [<c10bf8a8>] SyS_delete_module+0x158/0x1f0 [ 161.003480] [<c1173d5d>] ? ____fput+0xd/0x10 [ 161.003488] [<c106f0fe>] ? task_work_run+0x7e/0xb0 [ 161.003499] [<c165a68d>] sysenter_do_call+0x12/0x28 [ 161.003505] Code: 0f b6 4d f3 8d 51 0f 83 e1 f0 83 e2 0f 09 d1 84 d2 88 48 54 75 07 80 a7 91 00 00 00 7f 83 c4 04 5b 5e 5f 5d c3 8d b6 00 00 00 00 <0f> 0b 8d b6 00 00 00 00 55 89 e5 57 56 53 83 ec 64 3e 8d 74 26 [ 161.003586] EIP: [<f84861f8>] i915_gem_object_ggtt_unpin+0x88/0x90 [i915] SS:ESP 0068:dbe0fe0c Reported-by: Jesse Barnes <jess@xxxxxxxxxxxxxxxx> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=73985 Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> Cc: Jesse Barnes <jess@xxxxxxxxxxxxxxxx> Cc: Ben Widawsky <benjamin.widawsky@xxxxxxxxx> --- drivers/gpu/drm/i915/i915_gem_context.c | 41 ++++++++++++++++++--------------- 1 file changed, 23 insertions(+), 18 deletions(-) diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c index fed9aaf14465..bc12d31517e7 100644 --- a/drivers/gpu/drm/i915/i915_gem_context.c +++ b/drivers/gpu/drm/i915/i915_gem_context.c @@ -252,6 +252,7 @@ i915_gem_create_context(struct drm_device *dev, struct drm_i915_file_private *file_priv, bool create_vm) { + const bool is_default_ctx = file_priv == NULL; struct drm_i915_private *dev_priv = dev->dev_private; struct i915_hw_context *ctx; int ret = 0; @@ -262,6 +263,22 @@ i915_gem_create_context(struct drm_device *dev, if (IS_ERR(ctx)) return ctx; + if (is_default_ctx) { + /* We may need to do things with the shrinker which + * require us to immediately switch back to the default + * context. This can cause a problem as pinning the + * default context also requires GTT space which may not + * be available. To avoid this we always pin the default + * context. + */ + ret = i915_gem_obj_ggtt_pin(ctx->obj, + get_context_alignment(dev), 0); + if (ret) { + DRM_DEBUG_DRIVER("Couldn't pin %d\n", ret); + goto err_destroy; + } + } + if (create_vm) { struct i915_hw_ppgtt *ppgtt = create_vm_for_ctx(dev, ctx); @@ -269,34 +286,19 @@ i915_gem_create_context(struct drm_device *dev, DRM_DEBUG_DRIVER("PPGTT setup failed (%ld)\n", PTR_ERR(ppgtt)); ret = PTR_ERR(ppgtt); - goto err_destroy; + goto err_unpin; } else ctx->vm = &ppgtt->base; /* This case is reserved for the global default context and * should only happen once. */ - if (!file_priv) { + if (is_default_ctx) { if (WARN_ON(dev_priv->mm.aliasing_ppgtt)) { ret = -EEXIST; - goto err_destroy; + goto err_unpin; } dev_priv->mm.aliasing_ppgtt = ppgtt; - - /* We may need to do things with the shrinker which - * require us to immediately switch back to the default - * context. This can cause a problem as pinning the - * default context also requires GTT space which may not - * be available. To avoid this we always pin the default - * context. - */ - ret = i915_gem_obj_ggtt_pin(ctx->obj, - get_context_alignment(dev), 0); - if (ret) { - DRM_DEBUG_DRIVER("Couldn't pin %d\n", ret); - goto err_destroy; - } - ctx->vm = &dev_priv->mm.aliasing_ppgtt->base; } } else if (USES_ALIASING_PPGTT(dev)) { @@ -309,6 +311,9 @@ i915_gem_create_context(struct drm_device *dev, return ctx; +err_unpin: + if (is_default_ctx) + i915_gem_object_ggtt_unpin(ctx->obj); err_destroy: i915_gem_context_unreference(ctx); return ERR_PTR(ret); -- 1.8.5.3 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
