On Fri, 2026-07-03 at 15:08 +0200, Christian König wrote: > Arun please take a look at this. > > Thanks, > Christian.
FWIW Sashiko claims there is yet another pre-existing bug WRT ordering here, but since the fix wasn't needed for the rest of the series, I focused on this one. Thanks, Thomas > > 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 <[email protected]> > > Closes: > > https://sashiko.dev/#/patchset/[email protected]?part=4 > > Fixes: 2b624a2c1865 ("drm/ttm: Handle cgroup based eviction in > > TTM") > > Cc: Friedrich Vock <[email protected]> > > Cc: Maarten Lankhorst <[email protected]> > > Cc: Tejun Heo <[email protected]> > > Cc: Maxime Ripard <[email protected]> > > Cc: Christian König <[email protected]> > > Cc: Alex Deucher <[email protected]> > > Cc: [email protected] > > Cc: [email protected] > > Cc: <[email protected]> # v6.14+ > > Assisted-by: GitHub_Copilot:claude-sonnet-4.6 > > Signed-off-by: Thomas Hellström <[email protected]> > > --- > > 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;
