drm/panthor: Recover from panthor_gpu_flush_caches() failures

CVE-2025-71314

What is CVE-2025-71314?

In the Linux kernel, the following vulnerability has been resolved:

drm/panthor: Recover from panthor_gpu_flush_caches() failures

We have seen a few cases where the whole memory subsystem is blocked and flush operations never complete. When that happens, we want to:

• schedule a reset, so we can recover from this situation
• in the reset path, we need to reset the pending_reqs so we can send new commands after the reset
• if more panthor_gpu_flush_caches() operations are queued after the timeout, we skip them and return -EIO directly to avoid needless waits (the memory block won't miraculously work again)

Note that we drop the WARN_ON()s because these hangs can be triggered with buggy GPU jobs created by the UMD, and there's no way we can prevent it. We do keep the error messages though.

v2:

• New patch

v3:

• Collect R-b
• Explicitly mention the fact we dropped the WARN_ON()s in the commit message

v4:

• No changes

References