[Intel-gfx] [PATCH] drm/i915: Fix vmap_batch page iterator overrun

[shuang.he at intel.com]

Tested-By: PRC QA PRTS (Patch Regression Test System Contact: shuang.he at intel.com)
Task id: 5947
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
PNV                                  276/276              276/276
ILK                                  303/303              303/303
SNB                                  279/279              279/279
IVB                                  343/343              343/343
BYT                                  287/287              287/287
HSW                                  363/363              363/363
BDW                                  308/308              308/308
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
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