drm/i915/selftests: Fix i915_address_space refcnt leak

igt_ppgtt_pin_update() invokes i915_gem_context_get_vm_rcu(), which
returns a reference of the i915_address_space object to "vm" with
increased refcount.

When igt_ppgtt_pin_update() returns, "vm" becomes invalid, so the
refcount should be decreased to keep refcount balanced.

The reference counting issue happens in two exception handling paths of
igt_ppgtt_pin_update(). When i915_gem_object_create_internal() returns
IS_ERR, the refcnt increased by i915_gem_context_get_vm_rcu() is not
decreased, causing a refcnt leak.

Fix this issue by jumping to "out_vm" label when
i915_gem_object_create_internal() returns IS_ERR.

Fixes: a4e7ccdac38e ("drm/i915: Move context management under GEM")
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/1587361342-83494-1-git-send-email-xiyuyang19@fudan.edu.cn
(cherry picked from commit e07c7606a00c4361bad72ff4e72ed0dfbefa23b0)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

diff --git a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
index 2d0fd50..d4f94ca 100644 (file)
--- a/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
+++ b/drivers/gpu/drm/i915/gem/selftests/huge_pages.c
@@ -1477,8 +1477,10 @@ static int igt_ppgtt_pin_update(void *arg)
                unsigned int page_size = BIT(first);
 
                obj = i915_gem_object_create_internal(dev_priv, page_size);
-               if (IS_ERR(obj))
-                       return PTR_ERR(obj);
+               if (IS_ERR(obj)) {
+                       err = PTR_ERR(obj);
+                       goto out_vm;
+               }
 
                vma = i915_vma_instance(obj, vm, NULL);
                if (IS_ERR(vma)) {
@@ -1531,8 +1533,10 @@ static int igt_ppgtt_pin_update(void *arg)
        }
 
        obj = i915_gem_object_create_internal(dev_priv, PAGE_SIZE);
-       if (IS_ERR(obj))
-               return PTR_ERR(obj);
+       if (IS_ERR(obj)) {
+               err = PTR_ERR(obj);
+               goto out_vm;
+       }
 
        vma = i915_vma_instance(obj, vm, NULL);
        if (IS_ERR(vma)) {