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From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Cc: linux-rdma <linux-rdma@vger.kernel.org>,
	"Intel Graphics Development" <intel-gfx@lists.freedesktop.org>,
	"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"amd-gfx list" <amd-gfx@lists.freedesktop.org>,
	"Chris Wilson" <chris@chris-wilson.co.uk>,
	"moderated list:DMA BUFFER SHARING FRAMEWORK"
	<linaro-mm-sig@lists.linaro.org>,
	"DRI Development" <dri-devel@lists.freedesktop.org>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Christian König" <christian.koenig@amd.com>,
	"open list:DMA BUFFER SHARING FRAMEWORK"
	<linux-media@vger.kernel.org>
Subject: Re: [PATCH 13/18] drm/amdgpu/dc: Stop dma_resv_lock inversion in commit_tail
Date: Fri, 5 Jun 2020 14:41:34 +0200
Message-ID: <CAKMK7uG6VN93ZS3Rbi6edvDAMefXJ6CotMx5j916VcUy2nuvqQ@mail.gmail.com> (raw)
In-Reply-To: <e0bfd872-5d38-6718-a23d-6b14b3c14f25@amd.com>

On Fri, Jun 5, 2020 at 10:30 AM Pierre-Eric Pelloux-Prayer
<pierre-eric.pelloux-prayer@amd.com> wrote:
>
> Hi Daniel,
>
> On 04/06/2020 10:12, Daniel Vetter wrote:
> [...]
> > @@ -6910,7 +6910,11 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state,
> >                * explicitly on fences instead
> >                * and in general should be called for
> >                * blocking commit to as per framework helpers
> > +              *
> > +              * Yes, this deadlocks, since you're calling dma_resv_lock in a
> > +              * path that leads to a dma_fence_signal(). Don't do that.
> >                */
> > +#if 0
> >               r = amdgpu_bo_reserve(abo, true);
> >               if (unlikely(r != 0))
> >                       DRM_ERROR("failed to reserve buffer before flip\n");
> > @@ -6920,6 +6924,12 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state,
> >               tmz_surface = amdgpu_bo_encrypted(abo);
> >
> >               amdgpu_bo_unreserve(abo);
> > +#endif
> > +             /*
> > +              * this races anyway, so READ_ONCE isn't any better or worse
> > +              * than the stuff above. Except the stuff above can deadlock.
> > +              */
> > +             tiling_flags = READ_ONCE(abo->tiling_flags);
>
> With this change "tmz_surface" won't be initialized properly.
> Adding the following line should fix it:
>
>   tmz_surface = READ_ONCE(abo->flags) & AMDGPU_GEM_CREATE_ENCRYPTED;

So to make this clear, I'm not really proposing to fix up all the
drivers in detail. There's a lot more bugs in all the other drivers,
I'm pretty sure. The driver fixups really are just quick hacks to
illustrate the problem, and at least in some cases, maybe illustrate a
possible solution.

For the real fixes I think this needs driver teams working on this,
and make sure it's all solid. I can help a bit with review (especially
for placing the annotations, e.g. the one I put in cs_submit()
annotates a bit too much), but that's it.

Also I think the patch is from before tmz landed, and I just blindly
rebased over it :-)
-Daniel

>
>
> Pierre-Eric
>
>
> >
> >               fill_dc_plane_info_and_addr(
> >                       dm->adev, new_plane_state, tiling_flags,
> >



-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch
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  reply index

Thread overview: 106+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-04  8:12 [PATCH 00/18] dma-fence lockdep annotations, round 2 Daniel Vetter
2020-06-04  8:12 ` [PATCH 01/18] mm: Track mmu notifiers in fs_reclaim_acquire/release Daniel Vetter
2020-06-10 12:01   ` Thomas Hellström (Intel)
2020-06-10 12:25     ` [Intel-gfx] " Daniel Vetter
2020-06-10 19:41   ` [PATCH] " Daniel Vetter
2020-06-11 14:29     ` Jason Gunthorpe
2020-06-21 17:42     ` Qian Cai
2020-06-21 18:07       ` Daniel Vetter
2020-06-21 20:01         ` Daniel Vetter
2020-06-21 22:09           ` Qian Cai
2020-06-23 16:17           ` Qian Cai
2020-06-23 22:13             ` Daniel Vetter
2020-06-23 22:29               ` Qian Cai
2020-06-23 22:31       ` Dave Chinner
2020-06-23 22:36         ` Daniel Vetter
2020-06-21 17:00   ` [PATCH 01/18] " Qian Cai
2020-06-21 17:28     ` Daniel Vetter
2020-06-21 17:46       ` Qian Cai
2020-06-04  8:12 ` [PATCH 02/18] dma-buf: minor doc touch-ups Daniel Vetter
2020-06-10 13:07   ` Thomas Hellström (Intel)
2020-06-04  8:12 ` [PATCH 03/18] dma-fence: basic lockdep annotations Daniel Vetter
2020-06-04  8:57   ` Thomas Hellström (Intel)
2020-06-04  9:21     ` Daniel Vetter
2020-06-04  9:26       ` Chris Wilson
2020-06-04  9:36         ` [Intel-gfx] " Daniel Vetter
2020-06-05 13:29   ` [PATCH] " Daniel Vetter
2020-06-05 14:30     ` Thomas Hellström (Intel)
2020-06-11  9:57     ` Maarten Lankhorst
2020-06-10 14:21   ` [Intel-gfx] [PATCH 03/18] " Tvrtko Ursulin
2020-06-10 15:17     ` Daniel Vetter
2020-06-11 10:36       ` Tvrtko Ursulin
2020-06-11 11:29         ` Daniel Vetter
2020-06-11 14:29           ` Tvrtko Ursulin
2020-06-11 15:03             ` Daniel Vetter
2020-06-11  8:00   ` Chris Wilson
2020-06-11  8:44     ` Dave Airlie
2020-06-11  9:01       ` [Intel-gfx] " Daniel Stone
2020-06-19  8:25         ` Chris Wilson
2020-06-19  8:51           ` Daniel Vetter
2020-06-19  9:13             ` Chris Wilson
2020-06-19  9:43               ` Daniel Vetter
2020-06-19 13:12                 ` Chris Wilson
2020-06-22  9:16                   ` Daniel Vetter
2020-07-09  7:29                 ` Daniel Stone
2020-07-09  8:01                   ` Daniel Vetter
2020-06-12  7:06   ` [PATCH] " Daniel Vetter
2020-06-04  8:12 ` [PATCH 04/18] dma-fence: prime " Daniel Vetter
2020-06-11  7:30   ` [Linaro-mm-sig] " Thomas Hellström (Intel)
2020-06-11  8:34     ` Daniel Vetter
2020-06-11 14:15       ` Jason Gunthorpe
2020-06-11 23:35         ` Felix Kuehling
2020-06-12  5:11           ` Daniel Vetter
2020-06-19 18:13           ` Jerome Glisse
2020-06-23  7:39           ` Daniel Vetter
2020-06-23 18:44             ` Felix Kuehling
2020-06-23 19:02               ` Daniel Vetter
2020-06-16 12:07         ` Daniel Vetter
2020-06-16 14:53           ` Jason Gunthorpe
2020-06-17  7:57             ` Daniel Vetter
2020-06-17 15:29               ` Jason Gunthorpe
2020-06-18 14:42                 ` Daniel Vetter
2020-06-17  6:48           ` Daniel Vetter
2020-06-17 15:28             ` Jason Gunthorpe
2020-06-18 15:00               ` Daniel Vetter
2020-06-18 17:23                 ` Jason Gunthorpe
2020-06-19  7:22                   ` Daniel Vetter
2020-06-19 11:39                     ` Jason Gunthorpe
2020-06-19 15:06                       ` Daniel Vetter
2020-06-19 15:15                         ` Jason Gunthorpe
2020-06-19 16:19                           ` Daniel Vetter
2020-06-19 17:23                             ` Jason Gunthorpe
2020-06-19 18:09                               ` Jerome Glisse
2020-06-19 18:18                                 ` Jason Gunthorpe
2020-06-19 19:48                                   ` Felix Kuehling
2020-06-19 19:55                                     ` Jason Gunthorpe
2020-06-19 20:03                                       ` Felix Kuehling
2020-06-19 20:31                                       ` Jerome Glisse
2020-06-22 11:46                                         ` Jason Gunthorpe
2020-06-22 20:15                                           ` Jerome Glisse
2020-06-23  0:02                                             ` Jason Gunthorpe
2020-06-19 20:10                                   ` Jerome Glisse
2020-06-19 20:43                                     ` Daniel Vetter
2020-06-19 20:59                                       ` Jerome Glisse
2020-06-23  0:05                                     ` Jason Gunthorpe
2020-06-19 19:11                                 ` Alex Deucher
2020-06-19 19:30                                   ` Felix Kuehling
2020-06-19 19:40                                     ` Jerome Glisse
2020-06-19 19:51                                     ` Jason Gunthorpe
2020-06-12  7:01   ` [PATCH] " Daniel Vetter
2020-06-04  8:12 ` [PATCH 05/18] drm/vkms: Annotate vblank timer Daniel Vetter
2020-06-04  8:12 ` [PATCH 06/18] drm/vblank: Annotate with dma-fence signalling section Daniel Vetter
2020-06-04  8:12 ` [PATCH 07/18] drm/atomic-helper: Add dma-fence annotations Daniel Vetter
2020-06-04  8:12 ` [PATCH 08/18] drm/amdgpu: add dma-fence annotations to atomic commit path Daniel Vetter
2020-06-23 10:51   ` Daniel Vetter
2020-06-04  8:12 ` [PATCH 09/18] drm/scheduler: use dma-fence annotations in main thread Daniel Vetter
2020-06-04  8:12 ` [PATCH 10/18] drm/amdgpu: use dma-fence annotations in cs_submit() Daniel Vetter
2020-06-04  8:12 ` [PATCH 11/18] drm/amdgpu: s/GFP_KERNEL/GFP_ATOMIC in scheduler code Daniel Vetter
2020-06-04  8:12 ` [PATCH 12/18] drm/amdgpu: DC also loves to allocate stuff where it shouldn't Daniel Vetter
2020-06-04  8:12 ` [PATCH 13/18] drm/amdgpu/dc: Stop dma_resv_lock inversion in commit_tail Daniel Vetter
2020-06-05  8:30   ` Pierre-Eric Pelloux-Prayer
2020-06-05 12:41     ` Daniel Vetter [this message]
2020-06-04  8:12 ` [PATCH 14/18] drm/scheduler: use dma-fence annotations in tdr work Daniel Vetter
2020-06-04  8:12 ` [PATCH 15/18] drm/amdgpu: use dma-fence annotations for gpu reset code Daniel Vetter
2020-06-04  8:12 ` [PATCH 16/18] Revert "drm/amdgpu: add fbdev suspend/resume on gpu reset" Daniel Vetter
2020-06-04  8:12 ` [PATCH 17/18] drm/amdgpu: gpu recovery does full modesets Daniel Vetter
2020-06-04  8:12 ` [PATCH 18/18] drm/i915: Annotate dma_fence_work Daniel Vetter

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