Re: [PATCH v7 1/6] drm/amdgpu: Fix init ordering in amdgpu_vram_mgr_init()

["Thomas Hellström" <thomas.hellstrom@linux.intel.com>]

Hi, Maarten,

On Tue, 2026-07-21 at 13:46 +0200, Maarten Lankhorst wrote:
> Hey,
> 
> Can I merge this through drm-misc-next together with the rest of the
> series?
> 
> Kind regards
> ~Maarten

For the xe patches, Ack from me.

I do have a v8 that fixes a sashiko comment on the last patch, though,
but I was holding that awaiting a review on the other patches.

Thanks,
Thomas



> 
> On 7/7/26 20:05, Arunpravin Paneer Selvam wrote:
> > 
> > 
> > On 7/3/2026 6:38 PM, Christian König wrote:
> > > Arun please take a look at this.
> > Sure Christian. This fix looks correct to me.
> > Reviewed-by: Arunpravin Paneer Selvam
> > <Arunpravin.PaneerSelvam@amd.com>
> > 
> > Thanks,
> > Arun.
> > > 
> > > Thanks,
> > > Christian.
> > > 
> > > On 7/3/26 15:05, Thomas Hellström wrote:
> > > > 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>
> > > > ---
> > > >   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 2a241a5b12c4..ac3f71d77140 100644
> > > > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> > > > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vram_mgr.c
> > > > @@ -918,9 +918,6 @@ 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);
> > > >   @@ -935,6 +932,10 @@ 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;
> >