Description
In the Linux kernel, the following vulnerability has been resolved: sched_ext: Fix stall when a task enqueued with SCX_ENQ_LAST lands back on its CPU's local DSQ With SCX_OPS_ENQ_LAST, the last runnable task on a CPU is passed to ops.enqueue() instead of being kept running. Exiting tasks without SCX_OPS_ENQ_EXITING, migration disabled tasks without SCX_OPS_ENQ_MIGRATION_DISABLED and tasks on an offline rq skip ops.enqueue() and go straight to the local DSQ. This happens in put_prev_task_scx() after the pick has settled on idle, so nothing reschedules the CPU, which idles with the task queued until an unrelated wakeup lands on it or the watchdog fires. scx_mitosis, which sets SCX_OPS_ENQ_LAST without SCX_OPS_ENQ_EXITING, hit this during mass cgroup teardown: exiting tasks stuck in exit_mmap() for over 40 seconds. A task put on the local DSQ runs, as anywhere else. If the SCX_ENQ_LAST enqueue left the task on this CPU's local DSQ, set need_resched on the task being switched in, as proxy_resched_idle() does. resched_curr() would flag the task being put instead, and __schedule() clears that right after the pick.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
f0e1a0643a59bf1f922fa209cec86a170b784f3f to < ea47eec058fc1b6a3c3c54870d24a8bdcb3e204daffectedf0e1a0643a59bf1f922fa209cec86a170b784f3f to < 8d891c218016b6145993e082e7f732cb69dd0e29affectedf0e1a0643a59bf1f922fa209cec86a170b784f3f to < 396ba6f04da3fd1fb5a3d1c9535bef3f967f4e59affectedf0e1a0643a59bf1f922fa209cec86a170b784f3f to < 7a9df76679633cf26e0fea882a684012c6ec245aaffected
Linux Linux
Default version status: affected
6.12affected0 to < 6.12unaffected6.12.115 to ≤ 6.12.*unaffected6.18.59 to ≤ 6.18.*unaffected7.2.13 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected