Commit d7eff46c authored by Philip Yang's avatar Philip Yang Committed by Alex Deucher
Browse files

drm/amdgpu: fix fdinfo race with process exit 



Get process vm root BO ref in case process is exiting and root BO is
freed, to avoid NULL pointer dereference backtrace:

BUG: unable to handle kernel NULL pointer dereference at
0000000000000000
Call Trace:
amdgpu_show_fdinfo+0xfe/0x2a0 [amdgpu]
seq_show+0x12c/0x180
seq_read+0x153/0x410
vfs_read+0x91/0x140[ 3427.206183]  ksys_read+0x4f/0xb0
do_syscall_64+0x5b/0x1a0
entry_SYSCALL_64_after_hwframe+0x65/0xca

Signed-off-by: default avatarPhilip Yang <Philip.Yang@amd.com>
Reviewed-by: default avatarFelix Kuehling <Felix.Kuehling@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 703677d9

drivers/gpu/drm/amd/amdgpu/amdgpu_fdinfo.c

+9 −2
Original line number Diff line number Diff line
@@ -59,6 +59,7 @@ void amdgpu_show_fdinfo(struct seq_file *m, struct file *f) 
	uint64_t vram_mem = 0, gtt_mem = 0, cpu_mem = 0;

	struct drm_file *file = f->private_data;

	struct amdgpu_device *adev = drm_to_adev(file->minor->dev);

	struct amdgpu_bo *root;

	int ret;



	ret = amdgpu_file_to_fpriv(f, &fpriv);
@@ -69,13 +70,19 @@ void amdgpu_show_fdinfo(struct seq_file *m, struct file *f) 
	dev = PCI_SLOT(adev->pdev->devfn);

	fn = PCI_FUNC(adev->pdev->devfn);



	ret = amdgpu_bo_reserve(fpriv->vm.root.bo, false);

	root = amdgpu_bo_ref(fpriv->vm.root.bo);

	if (!root)

		return;



	ret = amdgpu_bo_reserve(root, false);

	if (ret) {

		DRM_ERROR("Fail to reserve bo\n");

		return;

	}

	amdgpu_vm_get_memory(&fpriv->vm, &vram_mem, &gtt_mem, &cpu_mem);

	amdgpu_bo_unreserve(fpriv->vm.root.bo);

	amdgpu_bo_unreserve(root);

	amdgpu_bo_unref(&root);



	seq_printf(m, "pdev:\t%04x:%02x:%02x.%d\npasid:\t%u\n", domain, bus,

			dev, fn, fpriv->vm.pasid);

	seq_printf(m, "vram mem:\t%llu kB\n", vram_mem/1024UL);