[CLR] Fix hipMemUnmap segfault on multi-GPU: guard null device memory…

[jaydeeppatel1111]

… in PAL GetMemAccess.

Motivation

hipMemUnmap segfaults on Windows with 2 GPUs while passing with 1 GPU. Crash occurs inside pal::Device::GetMemAccess during the multi-device access-probe loop added for synchronous unmap.

Technical Details

hipMemUnmap segfaults on Windows with 2 GPUs while passing with 1 GPU. Crash occurs inside pal::Device::GetMemAccess during the multi-device access-probe loop added for synchronous unmap.

JIRA ID

ROCM-27508

Test Plan

Seg faulting failures from reported tests.
830 - Unit_hipMemVmm_Uncached (SEGFAULT)
1141 - Unit_hipPointerGetAttribute_ipc_capable (SEGFAULT)
2484 - Unit_hipMemRetainAllocationHandle_SetGet (SEGFAULT)
2485 - Unit_hipMemRetainAllocationHandle_NegTst (SEGFAULT)
2486 - Unit_hipMemRetainAllocationHandle_Capture (SEGFAULT)
2487 - Unit_hipGetProcAddress_VMM (SEGFAULT)
2492 - Unit_hipMemCreate_ChkDev2HstMemcpy_ReleaseHdlPostUnmap (SEGFAULT)
2493 - Unit_hipMemCreate_ChkDev2HstMemcpy_ReleaseHdlPreUse (SEGFAULT)
2494 - Unit_hipMemCreate_ChkWithMemset (SEGFAULT)
2497 - Unit_hipMemSetAccess_SegmentsAccess (SEGFAULT)
2498 - Unit_hipMemSetAccess_Vmm2PeerPeerMemCpy (SEGFAULT)
2499 - Unit_hipMemSetGetAccess_Capture (SEGFAULT)
2503 - Unit_hipMemMap_VMMMemoryReuse_SingleGPU (SEGFAULT)
2504 - Unit_hipMemMap_MapPartialVMMMem (SEGFAULT)
2505 - Unit_hipMemMap_Capture (SEGFAULT)
2507 - Unit_hipMemMap_Retrieve_AllocationHandle (SEGFAULT)
2508 - Unit_hipMemMap_Retrieve_MultiAllocationHandle (SEGFAULT)
2509 - Unit_hipMemMap_CheckAddMemObj (SEGFAULT)
2510 - Unit_hipMemMap_RoundTrip (SEGFAULT)
2511 - Unit_hipMemMap_ConcurrentDisjointMapsNoDeadlock (SEGFAULT)
2514 - Unit_hipMemUnmap_negative (SEGFAULT)
2515 - Unit_hipMemUnmap_Capture (SEGFAULT)
2516 - Unit_hipMemUnmap_CrossLinksTornDown (SEGFAULT)
2517 - Unit_hipMemUnmap_RemapCrossLinks (SEGFAULT)
2518 - Unit_hipMemUnmap_DirectPath_BasicRoundTrip (SEGFAULT)
2519 - Unit_hipMemUnmap_DirectPath_InFlightKernelDrained (SEGFAULT)

Test Result

Seg faulting failures from reported tests pass.

Submission Checklist

• Look over the contributing guidelines at https://github.com/ROCm/ROCm/blob/develop/CONTRIBUTING.md#pull-requests.

[therock-pr-bot]

❌ PR Check — Action Required

Check	Status	Details
🌿 Branch Name	✅ Pass	—
📝 PR Title/Description	❌ Fail	Error: Title does not follow Conventional Commits style. Expected: start with a valid type (feat, fix, docs, …). Desired format: type(optional-scope): short description ─── Error: PR description must reference a JIRA ID, ISSUE ID, or a GitHub closing keyword. Expected: include a JIRA ID / ISSUE ID line (separator : or -, or omitted; value may be a JIRA key, a number with/without #, or a link), OR a closing keyword + issue reference. Accepted examples: • JIRA ID : TESTAUTO-6039 • JIRA ID - #330 • JIRA ID #330 • ISSUE ID : TESTUTO-3334 • ISSUE ID #3334 • ISSUE ID - TESTAUTO-3433 • ISSUE ID : https://github.com/<org_name>/<repo_name>/issues/1234 • Closes #10 • Fixes octo-org/octo-repo#100 • Resolves: #123 • #123 • https://github.com/<org_name>/<repo_name>/issues/123 Current: no valid JIRA/ISSUE/closing-keyword reference found
⛔ Forbidden Files	✅ Pass	—
🧪 Unit Test	❌ Fail	Error: Source/code files changed without an accompanying unit test. Expected: add at least one test file named like test_<name>.py / test_<name>.cpp (or <name>_test.*). Current: code file(s) changed: projects/clr/rocclr/device/pal/paldevice.cpp; no test file found
🔎 pre-commit	⏳ Pending	⏳ Still running…
🚫 Draft PR	🔜 To Be Enabled	—
🚩 Feature Flag	🔜 To Be Enabled	—
📊 Code Coverage	🔜 To Be Enabled	—

⚠️ 2 policy check(s) failed. Please address the issues above before this PR can be Reviewed.

🚫 Please fix the failed policies

• ❌ PR Title/Description
• ❌ Unit Test

The Not ready to Review label was added to this PR. Once all policies pass, the label is removed automatically.

📖 Need help? See the Policy FAQ for details on every check and how to fix failures.

[therock-pr-bot]

🚫 Please fix the failed policies before requesting reviews.

The following policy checks failed:

• ❌ PR Title/Description
• ❌ Unit Test

The Not ready to Review label has been added to this PR.
Once all policies pass, the label will be removed automatically.

[Copilot]

Pull request overview

Fixes a multi-GPU Windows crash in the PAL backend where hipMemUnmap can probe a VA on a device that doesn’t physically back the allocation, leading to a null dereference inside pal::Device::GetMemAccess.

Changes:

• Switch GetMemAccess to query device backing without allocating (getDeviceMemory(*this, false)).
• Add a nullptr guard to avoid dereferencing a missing per-device memory backing.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[AidanBeltonS]

Generally looks fine, one change needed

[jaydeeppatel1111]

Hello @gandryey, @saleelk , Can you pls review this PR? thanks!