From: Steven Price <steven.price@arm.com>
To: "Boris Brezillon" <boris.brezillon@collabora.com>,
"Liviu Dudau" <liviu.dudau@arm.com>,
"Adrián Larumbe" <adrian.larumbe@collabora.com>
Cc: dri-devel@lists.freedesktop.org,
"David Airlie" <airlied@gmail.com>,
"Simona Vetter" <simona@ffwll.ch>,
"Akash Goel" <akash.goel@arm.com>,
"Rob Clark" <robin.clark@oss.qualcomm.com>,
"Sean Paul" <sean@poorly.run>,
"Konrad Dybcio" <konradybcio@kernel.org>,
"Akhil P Oommen" <akhilpo@oss.qualcomm.com>,
"Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>,
"Maxime Ripard" <mripard@kernel.org>,
"Thomas Zimmermann" <tzimmermann@suse.de>,
"Dmitry Osipenko" <dmitry.osipenko@collabora.com>,
"Chris Diamand" <chris.diamand@arm.com>,
"Danilo Krummrich" <dakr@kernel.org>,
"Matthew Brost" <matthew.brost@intel.com>,
"Thomas Hellström" <thomas.hellstrom@linux.intel.com>,
"Alice Ryhl" <aliceryhl@google.com>,
"Chia-I Wu" <olvaffe@gmail.com>,
kernel@collabora.com
Subject: Re: [PATCH v4 0/9] drm/panthor: Add a GEM shrinker
Date: Fri, 6 Mar 2026 11:58:11 +0000 [thread overview]
Message-ID: <61d9080c-48ea-41fa-a727-e1f63b3b8f61@arm.com> (raw)
In-Reply-To: <20260305124320.156606-1-boris.brezillon@collabora.com>
Hi Boris,
On 05/03/2026 12:43, Boris Brezillon wrote:
> Hello,
>
> This is an attempt at adding a GEM shrinker to panthor so the system
> can finally reclaim GPU memory.
>
> This implementation is losely based on the MSM shrinker (which is why
> I added the MSM maintainers in Cc), and it's relying on the drm_gpuvm
> eviction/validation infrastructure.
>
> I've only done very basic IGT-based [1] and chromium-based (opening
> a lot of tabs on Aquarium until the system starts reclaiming+swaping
> out GPU buffers) testing, but I'm posting this early so I can get
> preliminary feedback on the implementation. If someone knows about
> better tools/ways to test the shrinker, please let me know.
I did a very basic test with glmark and I can reproduce the below splat:
[ 290.502999] ------------[ cut here ]------------
[ 290.504338] refcount_t: underflow; use-after-free.
[ 290.504843] WARNING: lib/refcount.c:28 at refcount_warn_saturate+0xf4/0x144, CPU#5: kworker/u32:3/75
[ 290.505715] Modules linked in: panthor drm_gpuvm drm_exec gpu_sched
[ 290.506402] CPU: 5 UID: 0 PID: 75 Comm: kworker/u32:3 Not tainted 7.0.0-rc1-00176-g608e8196cd63 #202 PREEMPT
[ 290.507323] Hardware name: Radxa ROCK 5B (DT)
[ 290.507733] Workqueue: events_unbound commit_work
[ 290.508185] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 290.508835] pc : refcount_warn_saturate+0xf4/0x144
[ 290.509287] lr : refcount_warn_saturate+0xf4/0x144
[ 290.509741] sp : ffff800083cb3b80
[ 290.510056] x29: ffff800083cb3b80 x28: ffff8000821d1e88 x27: ffff00010fa058a0
[ 290.510724] x26: 0000000000000000 x25: 0000000000000000 x24: 00000000ffffffff
[ 290.511398] x23: ffff00010b149000 x22: ffff00010dd3a7c8 x21: ffff80008226c828
[ 290.512065] x20: ffff00010dd3a780 x19: ffff00010dd3a780 x18: 00000000ffffffff
[ 290.512735] x17: 00000000ffffffff x16: ffff800083cb3668 x15: 0000000000001e00
[ 290.513403] x14: ffff000102a8f69f x13: ffff8000821fb558 x12: 000000000000083d
[ 290.514074] x11: 00000000000002bf x10: ffff800082253558 x9 : ffff8000821fb558
[ 290.514746] x8 : 00000000ffffefff x7 : ffff800082253558 x6 : 80000000fffff000
[ 290.515414] x5 : ffff0001fef31588 x4 : 0000000000000000 x3 : ffff80017d1e5000
[ 290.516083] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff000102b61980
[ 290.516752] Call trace:
[ 290.516987] refcount_warn_saturate+0xf4/0x144 (P)
[ 290.517440] drm_sched_fence_release_scheduled+0xe0/0xe4 [gpu_sched]
[ 290.518046] dma_fence_release+0xb4/0x3cc
[ 290.518429] drm_sched_fence_release_finished+0x94/0xa8 [gpu_sched]
[ 290.519021] dma_fence_release+0xb4/0x3cc
[ 290.519401] dma_fence_array_release+0x94/0x104
[ 290.519829] dma_fence_release+0xb4/0x3cc
[ 290.520208] drm_atomic_helper_wait_for_fences+0x1a4/0x228
[ 290.520724] commit_tail+0x38/0x18c
[ 290.521056] commit_work+0x14/0x20
[ 290.521381] process_one_work+0x208/0x76c
[ 290.521763] worker_thread+0x1c4/0x36c
[ 290.522121] kthread+0x13c/0x148
[ 290.522430] ret_from_fork+0x10/0x20
[ 290.522774] irq event stamp: 2167444
[ 290.523114] hardirqs last enabled at (2167443): [<ffff80008016772c>] __up_console_sem+0x6c/0x80
[ 290.523941] hardirqs last disabled at (2167444): [<ffff80008132977c>] el1_brk64+0x20/0x60
[ 290.524703] softirqs last enabled at (2167428): [<ffff8000800c94c4>] handle_softirqs+0x604/0x61c
[ 290.525528] softirqs last disabled at (2167421): [<ffff8000800102d0>] __do_softirq+0x14/0x20
[ 290.526320] ---[ end trace 0000000000000000 ]---
I haven't yet dug into what's happening.
Thanks,
Steve
next prev parent reply other threads:[~2026-03-06 11:58 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-05 12:43 [PATCH v4 0/9] drm/panthor: Add a GEM shrinker Boris Brezillon
2026-03-05 12:43 ` [PATCH v4 1/9] drm/gem: Consider GEM object reclaimable if shrinking fails Boris Brezillon
2026-03-05 12:43 ` [PATCH v4 2/9] drm/panthor: Move panthor_gems_debugfs_init() to panthor_gem.c Boris Brezillon
2026-03-05 12:43 ` [PATCH v4 3/9] drm/panthor: Group panthor_kernel_bo_xxx() helpers Boris Brezillon
2026-03-05 12:43 ` [PATCH v4 4/9] drm/panthor: Don't call drm_gpuvm_bo_extobj_add() if the object is private Boris Brezillon
2026-03-05 12:43 ` [PATCH v4 5/9] drm/panthor: Part ways with drm_gem_shmem_object Boris Brezillon
2026-03-06 8:01 ` kernel test robot
2026-03-06 11:58 ` Steven Price
2026-03-06 12:15 ` Boris Brezillon
2026-03-06 12:17 ` Steven Price
2026-03-05 12:43 ` [PATCH v4 6/9] drm/panthor: Lazily allocate pages on mmap() Boris Brezillon
2026-03-05 12:43 ` [PATCH v4 7/9] drm/panthor: Split panthor_vm_prepare_map_op_ctx() to prepare for reclaim Boris Brezillon
2026-03-05 12:43 ` [PATCH v4 8/9] drm/panthor: Track the number of mmap on a BO Boris Brezillon
2026-03-05 12:43 ` [PATCH v4 9/9] drm/panthor: Add a GEM shrinker Boris Brezillon
2026-03-06 15:17 ` Steven Price
2026-03-09 10:44 ` Boris Brezillon
2026-03-06 11:58 ` Steven Price [this message]
2026-03-06 12:30 ` [PATCH v4 0/9] " Boris Brezillon
2026-03-06 15:13 ` Steven Price
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