laptop-kernel/tools/testing/selftests/sched_ext, branch master

selftests/sched_ext: Add a test for ops.dequeue() on remote local DSQ moves

2026-09-30T17:49:52Z

Add a dequeue_remote test that makes moves of tasks in the BPF scheduler's custody to another CPU's local DSQ the common case, both via SCX_DSQ_LOCAL_ON dispatch and via scx_bpf_dsq_move_to_local(). The BPF scheduler tracks each task's custody state and triggers scx_bpf_error() if a custody period doesn't end with exactly one ops.dequeue() before the task runs, or if it ends with an SCX_DEQ_CORE_SCHED_EXEC dequeue of a task without a core cookie. Without the previous patch, the test fails with: sched_ext: dequeue_remote: dequeue_remote.bpf.c:141: 15 (rcu_preempt): late ops.dequeue() with SCX_DEQ_CORE_SCHED_EXEC (enq_cpu=3 cpu=2 seq=1) ... ops_dequeue+0x114/0x170 set_next_task_scx+0x104/0x1e0 __pick_next_task+0xc7/0x180 __schedule+0x154/0x1870 Reviewed-by: Andrea Righi Assisted-by: Claude:claude-opus-5.5 Signed-off-by: Kuba Piecuch Signed-off-by: Tejun Heo

selftests/sched_ext: Check the cmask cid-form ops.enable() receives

2026-09-19T14:09:37Z

cid-form ops.enable() now hands the task's cmask to the scheduler and set_cmask() repeats it right after. Add a cid-form selftest that checks both against p->cpus_ptr, that they match each other, that the initial set_cmask() lands before set_weight() and before the task first becomes runnable, and that set_cmask() never precedes enable(), across class-switch enables, fork-path enables and live affinity changes. v2: Mismatch details returned through a caller-local struct instead of globals, alloc_words validated in the header check, loop bounded by nr_cids directly (Andrea Righi). Signed-off-by: Tejun Heo

selftests/sched_ext: Test that ops.dequeue() can iterate the consumed DSQ

2026-09-17T17:20:17Z

Add a scheduler whose ops.dequeue() iterates the source user DSQ with bpf_iter_scx_dsq. The iteration takes the DSQ's raw spinlock; on a kernel that runs ops.dequeue() while the consume path still holds that lock, the first task consumed self-deadlocks the CPU with IRQs disabled. The watchdog cannot recover from that state, so on an unfixed kernel this test wedges the system instead of failing cleanly. On a fixed kernel the scheduler runs clean and the test passes. Signed-off-by: fangqiurong Signed-off-by: Tejun Heo

selftests/sched_ext: Fix flaky ddsp failure tests on busy systems

2026-08-14T22:32:23Z

The ddsp_vtimelocal_fail and ddsp_bogus_dsq_fail tests skip calling scx_bpf_dsq_insert_vtime() if scx_bpf_pick_idle_cpu() fails to find an idle CPU (returns a negative error code). On loaded systems, this results in the tests skipping the very assertions they are meant to verify. Eliminate this flakiness by falling back to prev_cpu if no idle CPU is found, ensuring the illegal dispatch operations are unconditionally attempted and tested. Fixes: a5db7817af78 ("sched_ext: Add selftests") Signed-off-by: Michal Blaszczyk Signed-off-by: Tejun Heo

selftests/sched_ext: Make numa idle validation race-free

2026-08-14T22:24:24Z

A CPU returned by scx_bpf_pick_idle_cpu_node() can be re-advertised as idle by an idle-to-idle re-pick before the BPF program validates the selection, and the scx_bpf_pick_any_cpu_node() fallback doesn't claim the CPU at all. Asserting that the picked CPU is absent from the node's idle cpumask is therefore inherently racy. Follow the same approach as commit 12da4723b679 ("selftests/sched_ext: Make allowed_cpus idle validation race-free") and validate a stable local invariant instead: a CPU executing ops.select_cpu() in a non-idle scheduling context must not be advertised as idle in its node's idle cpumask. Keep the node-membership validation of the picked CPU, which is stable. Signed-off-by: Cheng-Yang Chou Signed-off-by: Tejun Heo

sched_ext: Merge branch 'for-7.2-fixes' into for-7.3

2026-08-12T16:46:28Z

Pull to receive: c10b216a072f ("sched/core: Handle pick_task() releasing the rq lock") f3629c63a4af ("sched/core: Make core-sched flips wait for in-flight selections") ffaab58d2175 ("sched_ext: Replace SCX_RQ_BAL_KEEP with a dispatch verdict return") 3dd52416e44a ("sched_ext: Fix this_rq() assumptions in dispatch kfuncs") f2da9587118d ("sched_ext: Count rq lock releases in rq->scx.lock_drop_seq") d954004205c1 ("sched_ext: Fix rq->core_pick corruption under core scheduling") for the pending core scheduling follow-ups and to resolve the conflicts with the code reorganization and cap gate work on for-7.3. ffaab58d2175 converts scx_dispatch_sched() to a dispatch verdict return which for-7.3 moved from ext.c into inlines.h. Resolved by applying the conversion to the relocated copy and combining balance_one()'s verdict returns with the scx_task_can_stay_on_cpu() gate from the cap work. ffaab58d2175 and 3dd52416e44a update scx_bpf_sub_dispatch() which for-7.3 moved into sub.c. Resolved by applying the scx_locked_rq() switch and the verdict test to the sub.c copy. f2da9587118d instruments the open-coded lock releases in consume_remote_task() which for-7.3 folded into switch_rq_lock(). Resolved by keeping the accounting in switch_rq_lock() which covers all its callers. d954004205c1 widens the put_prev_task_scx() WARN suppression to all core-sched rqs on the same condition that for-7.3 gated with scx_task_can_stay_on_cpu(). Resolved by combining both. Signed-off-by: Tejun Heo

selftests/sched_ext: Check skeleton open failure in exit test

2026-08-10T19:39:35Z

exit.c does not check the return value of exit__open(). If it returns NULL, which happens when the skeleton wrapper fails to allocate the object or open the BPF ELF, the very next line dereferences it via SCX_ENUM_INIT(). That macro expands to SCX_ENUM_SET(), which accesses skel->rodata, causing a NULL pointer dereference. Every other selftest guards this with SCX_FAIL_IF(!skel, ...); exit.c is the only one missing it. Fixes: a5db7817af78 ("sched_ext: Add selftests") Signed-off-by: Liang Luo Signed-off-by: Tejun Heo

selftests/sched_ext: Make allowed_cpus idle validation race-free

2026-08-03T16:21:11Z

A remotely selected CPU can be re-advertised as idle by an idle-to-idle re-pick before the BPF program validates the selection. Checking that the selected CPU remains absent from the idle mask is therefore inherently racy. Validate a stable local invariant instead: a CPU executing ops.select_cpu() or ops.enqueue() in a non-idle scheduling context must not be advertised as idle. Read the idle mask without modifying it and also validate selected CPUs against the requested domain and task affinity. Suggested-by: Kuba Piecuch Signed-off-by: Andrea Righi Reviewed-by: Kuba Piecuch Signed-off-by: Tejun Heo

selftests/sched_ext: Handle sleeping task affinity changes in numa test

2026-07-23T17:50:37Z

When a sleeping task's affinity is changed, task_cpu(p) can be outside of p->cpus_ptr until after select_task_rq() selects a new runqueue for the task during wakeup. Thus, the task's NUMA node determined by numa_select_cpu() can be completely outside of the task's cpumask, leading to scx_pick_{idle,any}_cpu_node() failing to find an eligible CPU and returning -EBUSY. This leads to the numa.bpf.c scheduler abnormally exiting with the following message in dmesg: sched_ext: numa: invalid CPU -16 scx_bpf_cpu_node+0x120/0x190 bpf_prog_0a34b8e0f515771f_numa_select_cpu+0x108/0x14e bpf__sched_ext_ops_select_cpu+0x4f/0xb4 select_task_rq_scx+0xb0/0x210 select_task_rq+0xa0/0xd0 __try_to_wake_up+0x196/0x650 complete_all+0x76/0x100 migration_cpu_stop+0x22b/0x300 cpu_stopper_thread+0xc1/0x180 smpboot_thread_fn+0x16b/0x230 kthread+0x2d7/0x350 ret_from_fork+0x1c2/0x350 ret_from_fork_asm+0x1a/0x30 Make numa_select_cpu() robust against this case by returning @prev_cpu if no CPU could be found in the selected NUMA node _and_ we have reason to believe that the task's affinity was changed while it was sleeping. Fixes: 5ae5161820e5 ("selftests/sched_ext: Add NUMA-aware scheduler test") Signed-off-by: Kuba Piecuch Signed-off-by: Tejun Heo

Merge branch 'for-7.2-fixes' into for-7.3

2026-07-09T21:41:10Z

Pull to receive: db4e9defd2e8 ("sched_ext: Record an error on errno-only sub-enable failure") 49b3378a750c ("sched_ext: Fix premature ops->priv publication in scx_alloc_and_add_sched()") e6979d05c6a6 ("tools/sched_ext: scx - Fix cmask_subset(), cmask_equal() and cmask_weight()") for further sub-sched changes and to resolve the conflicts with the sub-sched updates on for-7.3. db4e9defd2e8 adds scx_error() to the sub-enable err_disable sink which for-7.3 moved from ext.c into sub.c. Resolved by applying the fix to scx_sub_enable_workfn() in sub.c. 49b3378a750c drops RCU_INIT_POINTER() from an scx_alloc_and_add_sched() unwind label whose body changed with for-7.3's stall_cpus addition. Resolved by dropping the line from the updated unwind. Signed-off-by: Tejun Heo