CVE-2026-90432 sched_ext: Abort directly from the hardlockup handler

In the Linux kernel, the following vulnerability has been resolved: schedext: Abort directly from the hardlockup handler scxhardlockup defers the abort to an irqwork because exit claiming used to take scxschedlock and couldn't run from NMI. The deferral is now unnecessary - claiming is NMI-safe a...