From: Danilo Krummrich <dakr@kernel.org>
To: Rob Clark <robdclark@gmail.com>
Cc: dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org,
linux-arm-msm@vger.kernel.org,
Connor Abbott <cwabbott0@gmail.com>,
Rob Clark <robdclark@chromium.org>,
Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
Maxime Ripard <mripard@kernel.org>,
Thomas Zimmermann <tzimmermann@suse.de>,
David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v4 02/40] drm/gpuvm: Allow VAs to hold soft reference to BOs
Date: Thu, 15 May 2025 11:00:16 +0200 [thread overview]
Message-ID: <aCWtINcOUWciwx8L@pollux> (raw)
In-Reply-To: <20250514175527.42488-3-robdclark@gmail.com>
On Wed, May 14, 2025 at 10:53:16AM -0700, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
>
> Eases migration for drivers where VAs don't hold hard references to
> their associated BO, avoiding reference loops.
>
> In particular, msm uses soft references to optimistically keep around
> mappings until the BO is distroyed. Which obviously won't work if the
> VA (the mapping) is holding a reference to the BO.
Ick! This is all complicated enough. Allow drivers to bypass the proper
reference counting for GEM objects in the context of VM_BO structures seems like
an insane footgun.
I don't understand why MSM would need weak references here. Why does msm need
that, but nouveau, Xe, panthor, PowerVR do not?
next prev parent reply other threads:[~2025-05-15 9:00 UTC|newest]
Thread overview: 66+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-05-14 17:53 [PATCH v4 00/40] drm/msm: sparse / "VM_BIND" support Rob Clark
2025-05-14 17:53 ` [PATCH v4 01/40] drm/gpuvm: Don't require obj lock in destructor path Rob Clark
2025-05-15 8:54 ` Danilo Krummrich
2025-05-15 9:06 ` Danilo Krummrich
2025-05-15 17:35 ` Rob Clark
2025-05-15 17:55 ` Danilo Krummrich
2025-05-15 21:57 ` Rob Clark
2025-05-16 9:01 ` Danilo Krummrich
2025-05-16 16:20 ` Rob Clark
2025-05-20 21:25 ` Dave Airlie
2025-05-20 21:52 ` Rob Clark
2025-05-20 22:31 ` Dave Airlie
2025-05-20 22:56 ` Rob Clark
2025-05-23 2:51 ` Rob Clark
2025-05-23 6:28 ` Danilo Krummrich
2025-05-14 17:53 ` [PATCH v4 02/40] drm/gpuvm: Allow VAs to hold soft reference to BOs Rob Clark
2025-05-15 9:00 ` Danilo Krummrich [this message]
2025-05-15 14:59 ` Rob Clark
2025-05-15 15:30 ` Danilo Krummrich
2025-05-15 17:34 ` Rob Clark
2025-05-15 17:51 ` Danilo Krummrich
2025-05-15 20:10 ` Rob Clark
2025-05-14 17:53 ` [PATCH v4 03/40] drm/gem: Add ww_acquire_ctx support to drm_gem_lru_scan() Rob Clark
2025-05-14 17:53 ` [PATCH v4 04/40] drm/sched: Add enqueue credit limit Rob Clark
2025-05-14 17:53 ` [PATCH v4 05/40] iommu/io-pgtable-arm: Add quirk to quiet WARN_ON() Rob Clark
2025-05-15 14:33 ` Will Deacon
2025-05-15 14:48 ` Rob Clark
2025-05-20 11:31 ` Will Deacon
2025-05-20 13:06 ` Robin Murphy
2025-05-20 14:06 ` Will Deacon
2025-05-14 17:53 ` [PATCH v4 06/40] drm/msm: Rename msm_file_private -> msm_context Rob Clark
2025-05-14 17:53 ` [PATCH v4 07/40] drm/msm: Improve msm_context comments Rob Clark
2025-05-14 17:53 ` [PATCH v4 08/40] drm/msm: Rename msm_gem_address_space -> msm_gem_vm Rob Clark
2025-05-14 17:53 ` [PATCH v4 09/40] drm/msm: Remove vram carveout support Rob Clark
2025-05-14 17:53 ` [PATCH v4 10/40] drm/msm: Collapse vma allocation and initialization Rob Clark
2025-05-14 17:53 ` [PATCH v4 11/40] drm/msm: Collapse vma close and delete Rob Clark
2025-05-14 17:53 ` [PATCH v4 12/40] drm/msm: Don't close VMAs on purge Rob Clark
2025-05-14 17:53 ` [PATCH v4 13/40] drm/msm: drm_gpuvm conversion Rob Clark
2025-05-14 17:53 ` [PATCH v4 14/40] drm/msm: Convert vm locking Rob Clark
2025-05-14 17:53 ` [PATCH v4 15/40] drm/msm: Use drm_gpuvm types more Rob Clark
2025-05-14 17:53 ` [PATCH v4 16/40] drm/msm: Split out helper to get iommu prot flags Rob Clark
2025-05-14 17:53 ` [PATCH v4 17/40] drm/msm: Add mmu support for non-zero offset Rob Clark
2025-05-14 17:53 ` [PATCH v4 18/40] drm/msm: Add PRR support Rob Clark
2025-05-14 17:53 ` [PATCH v4 19/40] drm/msm: Rename msm_gem_vma_purge() -> _unmap() Rob Clark
2025-05-14 17:53 ` [PATCH v4 20/40] drm/msm: Drop queued submits on lastclose() Rob Clark
2025-05-14 17:53 ` [PATCH v4 21/40] drm/msm: Lazily create context VM Rob Clark
2025-05-14 17:53 ` [PATCH v4 22/40] drm/msm: Add opt-in for VM_BIND Rob Clark
2025-05-14 17:53 ` [PATCH v4 23/40] drm/msm: Mark VM as unusable on GPU hangs Rob Clark
2025-05-14 17:53 ` [PATCH v4 24/40] drm/msm: Add _NO_SHARE flag Rob Clark
2025-05-14 17:53 ` [PATCH v4 25/40] drm/msm: Crashdump prep for sparse mappings Rob Clark
2025-05-14 17:53 ` [PATCH v4 26/40] drm/msm: rd dumping " Rob Clark
2025-05-14 17:53 ` [PATCH v4 27/40] drm/msm: Crashdec support for sparse Rob Clark
2025-05-14 17:53 ` [PATCH v4 28/40] drm/msm: rd dumping " Rob Clark
2025-05-14 17:53 ` [PATCH v4 29/40] drm/msm: Extract out syncobj helpers Rob Clark
2025-05-14 17:53 ` [PATCH v4 30/40] drm/msm: Use DMA_RESV_USAGE_BOOKKEEP/KERNEL Rob Clark
2025-05-14 17:53 ` [PATCH v4 31/40] drm/msm: Add VM_BIND submitqueue Rob Clark
2025-05-14 17:53 ` [PATCH v4 32/40] drm/msm: Support IO_PGTABLE_QUIRK_NO_WARN_ON Rob Clark
2025-05-14 17:53 ` [PATCH v4 33/40] drm/msm: Support pgtable preallocation Rob Clark
2025-05-14 17:53 ` [PATCH v4 34/40] drm/msm: Split out map/unmap ops Rob Clark
2025-05-14 17:53 ` [PATCH v4 35/40] drm/msm: Add VM_BIND ioctl Rob Clark
2025-05-14 17:53 ` [PATCH v4 36/40] drm/msm: Add VM logging for VM_BIND updates Rob Clark
2025-05-14 17:53 ` [PATCH v4 37/40] drm/msm: Add VMA unmap reason Rob Clark
2025-05-14 17:53 ` [PATCH v4 38/40] drm/msm: Add mmu prealloc tracepoint Rob Clark
2025-05-14 17:53 ` [PATCH v4 39/40] drm/msm: use trylock for debugfs Rob Clark
2025-05-14 17:53 ` [PATCH v4 40/40] drm/msm: Bump UAPI version Rob Clark
-- strict thread matches above, loose matches on Subject: below --
2025-05-14 16:58 [PATCH v4 00/40] drm/msm: sparse / "VM_BIND" support Rob Clark
2025-05-14 16:59 ` [PATCH v4 02/40] drm/gpuvm: Allow VAs to hold soft reference to BOs Rob Clark
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