Merge pull request #11361 from alalek:ocl_use_host_mem_ptr_workaround

modules/core/src/ocl.cpp

@@ -4666,7 +4666,9 @@ public:
 #endif
             {
                 tempUMatFlags = UMatData::TEMP_UMAT;
-                if (u->origdata == cv::alignPtr(u->origdata, 4)) // There are OpenCL runtime issues for less aligned data
+                if (u->origdata == cv::alignPtr(u->origdata, 4)  // There are OpenCL runtime issues for less aligned data
+                    && !(u->originalUMatData && u->originalUMatData->handle)  // Avoid sharing of host memory between OpenCL buffers
+                )
                 {
                     handle = clCreateBuffer(ctx_handle, CL_MEM_USE_HOST_PTR|createFlags,
                                             u->size, u->origdata, &retval);

modules/core/src/umatrix.cpp

@@ -381,6 +381,7 @@ UMat Mat::getUMat(int accessFlags, UMatUsageFlags usageFlags) const
         if(!a)
             a = a0;
         new_u = a->allocate(dims, size.p, type(), data, step.p, accessFlags, usageFlags);
+        new_u->originalUMatData = u;
     }
     bool allocated = false;
     CV_TRY
@@ -404,7 +405,6 @@ UMat Mat::getUMat(int accessFlags, UMatUsageFlags usageFlags) const
             CV_Assert(new_u->tempUMat());
         }
 #endif
-        new_u->originalUMatData = u;
         CV_XADD(&(u->refcount), 1);
         CV_XADD(&(u->urefcount), 1);
     }