Thank you for your contribution! Sashiko AI review found 2 potential issue(s) to consider: - [High] Double allocation of `dma_resv` causes a permanent memory leak because `vm->_resv` is allocated twice and the first pointer is unconditionally overwritten. - [High] Calls to `i915_address_space_init()` ignore the new `-ENOMEM` error return value, leading to incomplete initialization and potential NULL pointer dereferences. --
commit 5239b0e3c5a536da51a7fa10affcf28e378bea31 Author: Christian König <[email protected]> drm/i915/gt: Use dma_resv_alloc for VM reservation objects Replaces the embedded dma_resv object in struct i915_address_space with a dynamically allocated pointer, returning int from initialization functions to properly handle allocation failures. > diff --git a/drivers/gpu/drm/i915/gt/intel_gtt.c > b/drivers/gpu/drm/i915/gt/intel_gtt.c > index 7b1bdb121c88d..670cbe0b8cc05 100644 > --- a/drivers/gpu/drm/i915/gt/intel_gtt.c > +++ b/drivers/gpu/drm/i915/gt/intel_gtt.c > @@ -258,7 +258,7 @@ void i915_vm_release(struct kref *kref) > queue_work(vm->i915->wq, &vm->release_work); > } > > -void i915_address_space_init(struct i915_address_space *vm, int subclass) > +int i915_address_space_init(struct i915_address_space *vm, int subclass) > { [Severity: High] Does this change leave some callers unhandled? i915_address_space_init() now returns an error code, but it appears some existing callers were not updated to check the return value. For instance, i915_dpt_create() in drivers/gpu/drm/i915/i915_dpt.c, as well as the mock tests in drivers/gpu/drm/i915/selftests/mock_gtt.c, seem to ignore this return value. If dma_resv_alloc() fails under memory pressure, it could leave vm->mm uninitialized and vm->_resv as NULL, which might lead to a panic later when the Display Page Table is used. [ ... ] > @@ -295,7 +295,10 @@ void i915_address_space_init(struct i915_address_space > *vm, int subclass) > might_alloc(GFP_KERNEL); > mutex_release(&vm->mutex.dep_map, _THIS_IP_); > } > - dma_resv_init(&vm->_resv); > + > + vm->_resv = dma_resv_alloc(); > + if (!vm->_resv) > + return -ENOMEM; [Severity: High] Could this unconditionally overwrite an already allocated vm->_resv pointer? The callers ppgtt_init() and ggtt_probe_hw() explicitly allocate vm->_resv before calling i915_address_space_init(), which then allocates it again here. This appears to cause a permanent memory leak of the first allocation on every successful VM initialization. > > GEM_BUG_ON(!vm->total); [ ... ] > diff --git a/drivers/gpu/drm/i915/gt/intel_ppgtt.c > b/drivers/gpu/drm/i915/gt/intel_ppgtt.c > index 72d8473a448b9..9abd4faa2e550 100644 > --- a/drivers/gpu/drm/i915/gt/intel_ppgtt.c > +++ b/drivers/gpu/drm/i915/gt/intel_ppgtt.c > @@ -315,9 +315,17 @@ void ppgtt_init(struct i915_ppgtt *ppgtt, struct > intel_gt *gt, > ppgtt->vm.total = BIT_ULL(RUNTIME_INFO(i915)->ppgtt_size); > ppgtt->vm.lmem_pt_obj_flags = lmem_pt_obj_flags; > > - dma_resv_init(&ppgtt->vm._resv); > - i915_address_space_init(&ppgtt->vm, VM_CLASS_PPGTT); > + ppgtt->vm._resv = dma_resv_alloc(); > + if (!ppgtt->vm._resv) > + return -ENOMEM; > + > + if (i915_address_space_init(&ppgtt->vm, VM_CLASS_PPGTT)) { > + dma_resv_put(ppgtt->vm._resv); > + return -ENOMEM; > + } [Severity: High] If i915_address_space_init() fails, does this leak the first allocation? Inside i915_address_space_init(), if its own dma_resv_alloc() fails, ppgtt->vm._resv is clobbered to NULL. When control returns here and dma_resv_put() is called, it will be passing NULL, leaving the original allocation leaked. -- Sashiko AI review · https://sashiko.dev/#/patchset/[email protected]?part=8
