[SYCL][UR][L0 v2] use blocking free when returning memory to the driver #17375
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This patch fixes undefined behavior when freeing memory that might still be in use. Using regular zeMemFree (as was done before this change) is unsafe. L0 spec says that for zeMemFree, the application must ensure the device is not referencing memory before it is freed. SYCL sets 'indirect access' flag for every kernel. This means that each kernel can potentially access any memory and hence it is unsafe to free any memory allocation during kernel execution (if that kernel was submitted at some point in time when that allocation was alive). This replaces the 'indirect access tracking' mechanism used in the legacy adapter (see https://github.com/intel/llvm/blob/4c9b19bdd8b4b95b865522d583b6252bda301d98/unified-runtime/source/adapters/level_zero/context.hpp#L153) Related clarification in the SYCL spec: KhronosGroup/SYCL-Docs#758
pbalcer
approved these changes
Mar 12, 2025
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@intel/llvm-gatekeepers this is ready to be merged |
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