[SYCL] Merge USMAllocContext for Sub-Devices and Sub-Sub-Devices

[uditagarwal97]

Problem:
Currently, sub-devices and sub-sub-devices have different USM allocation contexts (USMAllocContext) but they share the same ze_device_handle. This causes issues with USM memory allocation, for instance, double-free.

Proposed Fix:
I have merged the USMAllocContext of the sub-device and sub-sub-device.

[uditagarwal97]

The issue is reproducible on the existing test (the one being updated in intel/llvm-test-suite#1515).
We've only seen it internally because the project's CI doesn't use PVC machines currently.

[smaslov-intel]

Problem: Currently, sub-devices and sub-sub-devices have different USM allocation contexts (USMAllocContext) but they share the same ze_device_handle. This causes issues with USM memory allocation, for instance, double-free.

Proposed Fix: I have merged the USMAllocContext of the sub-device and sub-sub-device.

should we just avoid freeing the context of sub-sub-devices since they do not carry unique L0 device handle?

Tag @igchor , the new owner of USM allocators

[igchor]

Problem: Currently, sub-devices and sub-sub-devices have different USM allocation contexts (USMAllocContext) but they share the same ze_device_handle. This causes issues with USM memory allocation, for instance, double-free.

Proposed Fix: I have merged the USMAllocContext of the sub-device and sub-sub-device.

If the ze_device_handle is the same why not just use it as a key for DeviceMemAllocContexts, SharedMemAllocContexts and SharedReadOnlyMemAllocContexts instead of pi_device? This way you wouldn't have to create any shared ptrs - you could just call insert on unordered_map and if the key already exists, do nothing.

[smaslov-intel]

Problem: Currently, sub-devices and sub-sub-devices have different USM allocation contexts (USMAllocContext) but they share the same ze_device_handle. This causes issues with USM memory allocation, for instance, double-free.
Proposed Fix: I have merged the USMAllocContext of the sub-device and sub-sub-device.

If the ze_device_handle is the same why not just use it as a key for DeviceMemAllocContexts, SharedMemAllocContexts and SharedReadOnlyMemAllocContexts instead of pi_device? This way you wouldn't have to create any shared ptrs - you could just call insert on unordered_map and if the key already exists, do nothing.

Sounds good to me!

[uditagarwal97]

Thanks for the feedback, @igchor and @smaslov-intel. I have made the suggested changes.

[smaslov-intel]

Do we really need this intrinsic check here? I thought we would just add an USM allocator for each L0 device. For PI devices that don't have unique L0 device (like this CCS or sub-sub-devices) the allocator wouldn't be added since it would already be there (from sub-device)

[uditagarwal97]

Sure, I've removed the intrinsic check and instead added an extra comment to explicitly state the sharing of USM allocators between CCS and subdevices.

[smaslov-intel]

LGTM

[igchor]

LGTM

[uditagarwal97]

Failure in SYCL :: dword_atomic_smoke.cpp is known #8098

[uditagarwal97]

@intel/llvm-gatekeepers The PR is ready!