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由 Chris Wilson 提交于
Sometimes we know we are the only user of the bo, but since we take a protective pin_pages early on, an attempt to change the vmap on the object is denied because it is busy. i915_gem_object_pin_map() cannot tell from our single pin_count if the operation is safe. Instead we must pass that information down from the caller in the manner of I915_MAP_OVERRIDE. This issue has existed from the introduction of the mapping, but was never noticed as the only place where this conflict might happen is for cached kernel buffers (such as allocated by i915_gem_batch_pool_get()). Until recently there was only a single user (the cmdparser) so no conflicts ever occurred. However, we now use it to allocate batches for different operations (using MAP_WC on !llc for writes) in addition to the existing shadow batch (using MAP_WB for reads). We could either keep both mappings cached, or use a different write mechanism if we detect a MAP_WB already exists (i.e. clflush afterwards), but as we haven't seen this issue in the wild (it requires hitting the GPU reloc path in addition to the cmdparser) for simplicity just allow the mappings to be recreated. v2: Include the i915_MAP_OVERRIDE bit in the enum so the compiler knows about all the valid values. Fixes: 7dd4f672 ("drm/i915: Async GPU relocation processing") Testcase: igt/gem_lut_handle # byt, completely by accident Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20170828104631.8606-1-chris@chris-wilson.co.ukReviewed-by: NJoonas Lahtinen <joonas.lahtinen@linux.intel.com> (cherry picked from commit a575c676) Signed-off-by: NRodrigo Vivi <rodrigo.vivi@intel.com>
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