[PATCH] drm/gpusvm: Fix MM reference leak in drm_gpusvm_range_evict

[Matthew Brost <matthew.brost@intel.com>]

If kvmalloc_array() fails in drm_gpusvm_range_evict(), the MM
reference acquired earlier is not released, resulting in a reference
leak.

Fix this by dropping the MM reference on the kvmalloc_array()
failure path.

Fixes: 99624bdff867 ("drm/gpusvm: Add support for GPU Shared Virtual Memory")
Cc: stable@vger.kernel.org
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
---
 drivers/gpu/drm/drm_gpusvm.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/drm_gpusvm.c b/drivers/gpu/drm/drm_gpusvm.c
index f45bf1d59a06..ac1f135abe68 100644
--- a/drivers/gpu/drm/drm_gpusvm.c
+++ b/drivers/gpu/drm/drm_gpusvm.c
@@ -1778,8 +1778,10 @@ int drm_gpusvm_range_evict(struct drm_gpusvm *gpusvm,
 		return -EFAULT;
 
 	pfns = kvmalloc_array(npages, sizeof(*pfns), GFP_KERNEL);
-	if (!pfns)
+	if (!pfns) {
+		mmput(mm);
 		return -ENOMEM;
+	}
 
 	hmm_range.hmm_pfns = pfns;
 	while (!time_after(jiffies, timeout)) {
-- 
2.34.1