[Devel] [PATCH hci-8.1 0/1] drm/amdgpu: fix init ordering in amdgpu_vram_mgr_init()

[Devel] [PATCH hci-8.1 0/1] drm/amdgpu: fix init ordering in amdgpu_vram_mgr_init()

[Mirian Shilakadze]

Backport of the upstream stable fix e773798e14ac ("drm/amdgpu: Fix
init ordering in amdgpu_vram_mgr_init()"). It registers the dmem
region after the VRAM manager lists and buddy allocator are set up, so
a failed registration leaves a manager that can be torn down safely.
It is a clean cherry-pick, the changed lines are the same as upstream,
and it only moves the registration down, nothing else changes.

Not run: we have no node with an AMD GPU. Build-tested only,
amdgpu_vram_mgr.o compiles with the 211.52.1.22.19 config.

As far as I can tell from reading the code, the crash described
upstream cannot be triggered in our kernel. amdgpu_ttm_fini() is only
reached from the GMC block sw_fini, and amdgpu_device_ip_fini() skips
a block whose sw_init failed, so a failed registration just fails
the probe.

https://virtuozzo.atlassian.net/browse/VSTOR-153702

Thomas Hellström (1):
  ms/drm/amdgpu: Fix init ordering in amdgpu_vram_mgr_init()

 drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

-- 
2.43.0

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[Devel] [PATCH hci-8.1 1/1] ms/drm/amdgpu: Fix init ordering in amdgpu_vram_mgr_init()

[Mirian Shilakadze]

From: Thomas Hellström <thomas.hellstrom@linux.intel.com>

drmm_cgroup_register_region() is called before INIT_LIST_HEAD() and
gpu_buddy_init() in amdgpu_vram_mgr_init(). If it fails, the function
returns early and bypasses those initializations.

Since adev->mman.initialized is set to true before amdgpu_vram_mgr_init()
is called, a failure triggers amdgpu_ttm_fini(), which calls
amdgpu_vram_mgr_fini(), which then:

 - Calls list_for_each_entry_safe() on reservations_pending and
   reserved_pages, whose list_head::next pointers are zero-initialized
   (NULL). The loop does not recognize them as empty and dereferences NULL.

 - Calls gpu_buddy_fini(), which iterates free_trees[] unconditionally
   via for_each_free_tree(). Since mm->free_trees is NULL
   (never allocated), this dereferences NULL.

Both result in a kernel panic on the module load error path.

Fix by moving drmm_cgroup_register_region() to after the list and buddy
allocator are fully initialized, so the teardown path is safe to run.

Reported-by: Sashiko-bot <sashiko-bot@kernel.org>
Closes: https://sashiko.dev/#/patchset/20260428073116.15687-1-thomas.hellstrom@linux.intel.com?part=4
Fixes: 2b624a2c1865 ("drm/ttm: Handle cgroup based eviction in TTM")
Cc: Friedrich Vock <friedrich.vock@gmx.de>
Cc: Maarten Lankhorst <dev@lankhorst.se>
Cc: Tejun Heo <tj@kernel.org>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Christian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: amd-gfx@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Cc: stable@vger.kernel.org # v6.14+
Assisted-by: GitHub_Copilot:claude-sonnet-4.6
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Reviewed-by: Arunpravin Paneer Selvam <Arunpravin.PaneerSelvam@amd.com>
Reviewed-By: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Tested-by: Thadeu Lima de Souza Cascardo <cascardo@igalia.com>
Link: https://patch.msgid.link/20260725100036.2372-2-thomas.hellstrom@linux.intel.com
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
(cherry picked from commit e773798e14ac0aea54ca9676083b91f445e5bc59)

https://virtuozzo.atlassian.net/browse/VSTOR-153702
Feature: fix ms/drm

Signed-off-by: Mirian Shilakadze <mirian.shilakadze@virtuozzo.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
index 9d934c07fa6b..2e457a0388a3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
@@ -917,9 +917,6 @@ int amdgpu_vram_mgr_init(struct amdgpu_device *adev)
 	struct ttm_resource_manager *man = &mgr->manager;
 	int err;
 
-	man->cg = drmm_cgroup_register_region(adev_to_drm(adev), "vram", adev->gmc.real_vram_size);
-	if (IS_ERR(man->cg))
-		return PTR_ERR(man->cg);
 	ttm_resource_manager_init(man, &adev->mman.bdev,
 				  adev->gmc.real_vram_size);
 
@@ -934,6 +931,10 @@ int amdgpu_vram_mgr_init(struct amdgpu_device *adev)
 	if (err)
 		return err;
 
+	man->cg = drmm_cgroup_register_region(adev_to_drm(adev), "vram", adev->gmc.real_vram_size);
+	if (IS_ERR(man->cg))
+		return PTR_ERR(man->cg);
+
 	ttm_set_driver_manager(&adev->mman.bdev, TTM_PL_VRAM, &mgr->manager);
 	ttm_resource_manager_set_used(man, true);
 	return 0;
-- 
2.43.0

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Re: [Devel] [PATCH hci-8.1 1/1] ms/drm/amdgpu: Fix init ordering in amdgpu_vram_mgr_init()

[no-reply]

> From: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> 
> drmm_cgroup_register_region() is called before INIT_LIST_HEAD() and
> gpu_buddy_init() in amdgpu_vram_mgr_init(). If it fails, the function
> returns early and bypasses those initializations.
> 
> Since adev->mman.initialized is set to true before amdgpu_vram_mgr_init()
> is called, a failure triggers amdgpu_ttm_fini(), which calls
> amdgpu_vram_mgr_fini(), which then:
> 
>  - Calls list_for_each_entry_safe() on reservations_pending and
>    reserved_pages, whose list_head::next pointers are zero-initialized
>    (NULL). The loop does not recognize them as empty and dereferences NULL.
> 
>  - Calls gpu_buddy_fini(), which iterates free_trees[] unconditionally
> [ ... ]
> 
> https://virtuozzo.atlassian.net/browse/VSTOR-153702
> Feature: fix ms/drm
> 
> Signed-off-by: Mirian Shilakadze <mirian.shilakadze@virtuozzo.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261106145524.96305-1-mirian.shilakadze@virtuozzo.com?part=1


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