[Intel-gfx] [PATCH] drm/i915/display: cleanup intel_bw_state on i915 module removal

Tue Dec 17 19:39:05 UTC 2019

On Thu, Dec 12, 2019 at 12:34:49PM -0800, Lucas De Marchi wrote:
>On Thu, Dec 12, 2019 at 09:37:17AM -0800, Matt Roper wrote:
>>On Wed, Dec 11, 2019 at 04:22:50PM -0800, Lucas De Marchi wrote:
>>>On Wed, Dec 11, 2019 at 12:10:41PM +0530, Bharadiya,Pankaj wrote:
>>>> On Tue, Dec 10, 2019 at 09:57:39PM -0800, Lucas De Marchi wrote:
>>>> > On Mon, Dec 09, 2019 at 08:09:02PM +0530, Pankaj Bharadiya wrote:
>>>> > >intel_bw_state allocated memory is not getting freed even after
>>>> > >module removal.
>>>> > >
>>>> > >kmemleak reported backtrace:
>>>> > >
>>>> > >   [<0000000079019739>] kmemdup+0x17/0x40
>>>> > >   [<00000000d58c1b9d>] intel_bw_duplicate_state+0x1b/0x40 [i915]
>>>> > >   [<000000007423ed0c>] drm_atomic_get_private_obj_state+0xca/0x140
>>>> > >   [<00000000100e3533>] intel_bw_atomic_check+0x133/0x350 [i915]
>>>> > >   [<00000000126d0e0c>] intel_atomic_check+0x1ab7/0x20d0 [i915]
>>>> > >   [<00000000d5dfc004>] drm_atomic_check_only+0x563/0x810
>>>> > >   [<00000000c9379611>] drm_atomic_commit+0xe/0x50
>>>> > >   [<00000000ec82b765>] drm_atomic_helper_disable_all+0x133/0x160
>>>> > >   [<000000003c44760c>] drm_atomic_helper_shutdown+0x65/0xc0
>>>> > >   [<00000000414e3e5c>] i915_driver_remove+0xcb/0x130 [i915]
>>>> > >   [<00000000f8544c2a>] i915_pci_remove+0x19/0x40 [i915]
>>>> > >   [<000000002dcbd148>] pci_device_remove+0x36/0xb0
>>>> > >   [<000000003c8c6b0a>] device_release_driver_internal+0xe0/0x1c0
>>>> > >   [<00000000580e9566>] unbind_store+0xc3/0x120
>>>> > >   [<00000000869d0df5>] kernfs_fop_write+0x104/0x190
>>>> > >   [<000000004dc1a355>] vfs_write+0xb9/0x1d0
>>>> >
>>>> > what I find strange in this is that the last state was allocated by the
>>>> > "driver remove" code path.
>>>> >
>>>> > >
>>>> > >Call the drm_atomic_private_obj_fini(), which inturn calls the
>>>> > >intel_bw_destroy_state() to make sure the intel_bw_state memory is
>>>> > >freed properly.
>>>> > >
>>>> > >Signed-off-by: Pankaj Bharadiya <pankaj.laxminarayan.bharadiya at intel.com>
>>>> > >---
>>>> > >drivers/gpu/drm/i915/display/intel_bw.c      | 5 +++++
>>>> > >drivers/gpu/drm/i915/display/intel_bw.h      | 1 +
>>>> > >drivers/gpu/drm/i915/display/intel_display.c | 2 ++
>>>> > >3 files changed, 8 insertions(+)
>>>> > >
>>>> > >diff --git a/drivers/gpu/drm/i915/display/intel_bw.c b/drivers/gpu/drm/i915/display/intel_bw.c
>>>> > >index dcb66a33be9b..b228671d5a5d 100644
>>>> > >--- a/drivers/gpu/drm/i915/display/intel_bw.c
>>>> > >+++ b/drivers/gpu/drm/i915/display/intel_bw.c
>>>> > >@@ -486,3 +486,8 @@ int intel_bw_init(struct drm_i915_private *dev_priv)
>>>> > >
>>>> > >	return 0;
>>>> > >}
>>>> > >+
>>>> > >+void intel_bw_cleanup(struct drm_i915_private *dev_priv)
>>>> > >+{
>>>> > >+	drm_atomic_private_obj_fini(&dev_priv->bw_obj);
>>>> > >+}
>>>> > >diff --git a/drivers/gpu/drm/i915/display/intel_bw.h b/drivers/gpu/drm/i915/display/intel_bw.h
>>>> > >index 9db10af012f4..20b9ad241802 100644
>>>> > >--- a/drivers/gpu/drm/i915/display/intel_bw.h
>>>> > >+++ b/drivers/gpu/drm/i915/display/intel_bw.h
>>>> > >@@ -25,6 +25,7 @@ struct intel_bw_state {
>>>> > >
>>>> > >void intel_bw_init_hw(struct drm_i915_private *dev_priv);
>>>> > >int intel_bw_init(struct drm_i915_private *dev_priv);
>>>> > >+void intel_bw_cleanup(struct drm_i915_private *dev_priv);
>>>> > >int intel_bw_atomic_check(struct intel_atomic_state *state);
>>>> > >void intel_bw_crtc_update(struct intel_bw_state *bw_state,
>>>> > >			  const struct intel_crtc_state *crtc_state);
>>>> > >diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
>>>> > >index 3190aa27ffdc..756eb90b1bb1 100644
>>>> > >--- a/drivers/gpu/drm/i915/display/intel_display.c
>>>> > >+++ b/drivers/gpu/drm/i915/display/intel_display.c
>>>> > >@@ -17912,6 +17912,8 @@ void intel_modeset_driver_remove(struct drm_i915_private *i915)
>>>> > >
>>>> > >	intel_gmbus_teardown(i915);
>>>> > >
>>>> > >+	intel_bw_cleanup(i915);
>>>> >
>>>> > This doesn't seem to match the (reverse) order of
>>>> > intel_modeset_init()... but it's actually the gmbus_teardown() that is
>>>> > out of place. Did you check if it's not a wrong shutdown ordering?
>>>> >
>>>>
>>>> In intel_modeset_init(), intel_gmbus_setup() happens after
>>>> intel_bw_init().
>>>> I think the patch follows the reverse ordering properly.
>>>> Am I missing anything?
>>>
>>>I said it seems that it's the gmbus_teardown() that is out of place.
>>>Have you seen my comment above? Why are we duplicating the bw_state on
>>>the module-remove code path?
>>
>>I think that part is legitimate.  Part of the module remove sequence
>>does an atomic commit to turn everything off.  During atomic
>>transactions, we create duplicates of all modesetting state objects can
>>be modified; if/when the transaction succeeds, those duplicates are
>>swapped into the actual driver state and the old objects are destroyed.
>>Thus in cases like this where we forget to destroy a private object
>>state, that leaked state structure will be the one allocated during the
>>very last atomic transaction that happened (i.e., on the driver teardown
>>codepath).
>
>humn, that makes sense. The new duplicate state will replace the
>previous one and hence why we see it in the backtrace, rather than one
>allocated previously.
>
>thanks
>Lucas De Marchi

and...


Reviewed-by: Lucas De Marchi <lucas.demarchi at intel.com>

Lucas De Marchi

>
>>
>>
>>Matt
>>
>>>
>>>Lucas De Marchi
>>>
>>>>
>>>> Thanks,
>>>> Pankaj
>>>>
>>>> > thanks
>>>> > Lucas De Marchi
>>>> >
>>>> > >+
>>>> > >	destroy_workqueue(i915->flip_wq);
>>>> > >	destroy_workqueue(i915->modeset_wq);
>>>> > >
>>>> > >--
>>>> > >2.23.0
>>>> > >
>>>> > >_______________________________________________
>>>> > >Intel-gfx mailing list
>>>> > >Intel-gfx at lists.freedesktop.org
>>>> > >https://lists.freedesktop.org/mailman/listinfo/intel-gfx
>>
>>-- 
>>Matt Roper
>>Graphics Software Engineer
>>VTT-OSGC Platform Enablement
>>Intel Corporation
>>(916) 356-2795