drm/amdkfd: Use mmget_not_zero in MMU notifier

From Philip Yang
09c5cdbc62d99fc6306a21b24b60eb11a3bd0963 in linux 5.15.y/5.15.49
fa582c6f3684ac0098a9d02ddf0ed52a02b37127 in mainline linux

diff --git a/sys/dev/pci/drm/amd/amdkfd/kfd_svm.c b/sys/dev/pci/drm/amd/amdkfd/kfd_svm.c
index 830809b..74e6f61 100644 (file)
--- a/sys/dev/pci/drm/amd/amdkfd/kfd_svm.c
+++ b/sys/dev/pci/drm/amd/amdkfd/kfd_svm.c
@@ -2181,6 +2181,8 @@ svm_range_cpu_invalidate_pagetables(struct mmu_interval_notifier *mni,
 
        if (range->event == MMU_NOTIFY_RELEASE)
                return true;
+       if (!mmget_not_zero(mni->mm))
+               return true;
 
        start = mni->interval_tree.start;
        last = mni->interval_tree.last;
@@ -2207,6 +2209,7 @@ svm_range_cpu_invalidate_pagetables(struct mmu_interval_notifier *mni,
        }
 
        svm_range_unlock(prange);
+       mmput(mni->mm);
 
        return true;
 }