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

Thu Dec 12 20:34:49 UTC 2019

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

>
>
>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