kernel/git/stable/linux.git/tools/sched_ext, branch master

sched_ext: Merge branch 'for-7.3-arena-args' into for-7.3

2026-08-17T21:20:34+00:00

Pull to receive the __arena argument conversion: 67f1f4a48c24 ("sched_ext: Pass kernel arena pointers to ops_cid callbacks") a8dc810968af ("sched_ext: Convert sub-cap kfuncs to __arena cmask arguments") a05c5b5cb5cf ("sched_ext: Convert scx_bpf_cid_override() to __arena array arguments") along with the bpf-next branch carrying the __arena argument support they depend on. Conflict in kernel/sched/ext/ext.c between: c384ab8a0b13 ("sched_ext: Move the config-off sub-cap kfunc stubs into sub.c") and: a8dc810968af ("sched_ext: Convert sub-cap kfuncs to __arena cmask arguments") which updated the stubs in their old ext.c location. Resolved by keeping ext.c without the stubs and applying the prototype conversion to the relocated stubs in sub.c. Signed-off-by: Tejun Heo

sched_ext: Make core-sched task ordering hierarchy-aware

2026-08-16T02:07:49+00:00

With sub-schedulers, tasks of different schedulers routinely share rqs and SMT siblings, but scx_prio_less() consults ops.core_sched_before() only when both tasks belong to the same scheduler. Every pair spanning two schedulers falls back to the default ordering, so no scheduler can express ordering across a scheduler boundary, including a root over its sub-schedulers' tasks. Order a pair spanning schedulers by the nearest common ancestor that implements ops.core_sched_before(): both tasks are in its subtree, making this the one op where a scheduler is called on tasks it delegated to its sub-schedulers and may not be scheduling anymore. Same-scheduler pairs keep using the owning scheduler's op so a parent never orders inside a subtree it delegated. The op is skipped when the deciding scheduler is bypassing on either task's CPU. Update scx_qmap to fall back to the kernel's default ordering when handed a delegated task it has no task_ctx for. Signed-off-by: Tejun Heo

sched_ext: Fix inverted ops.core_sched_before() invocation

2026-08-16T02:07:49+00:00

scx_prio_less() implements prio_less() semantics - %true means that @a is the lower priority and should run after @b. ops.core_sched_before() is documented to return %true when @a should run before @b. scx_prio_less() returns the op's value as-is, inverting the documented semantics at runtime. Call the op with the arguments swapped. scx_qmap followed the wiring instead of the documentation and returned %true for the younger task, so the two inversions canceled out and it behaved as intended. Flip its comparison to match. scx_qmap is likely the only current user in or out of the kernel tree. Any scheduler written the same way needs the same flip, while schedulers following the documentation are fixed by this change. Fixes: 7b0888b7cc19 ("sched_ext: Implement core-sched support") Cc: stable@vger.kernel.org # v6.12+ Signed-off-by: Tejun Heo

sched_ext: Rename balance-era identifiers to dispatch terms

2026-08-15T10:07:42+00:00

sched_class->balance() is gone from sched_ext and what balance_one() does is run dispatch to produce something pickable. Update the balance-era names to dispatch terms: - balance_one() -> dispatch_one() - SCX_RQ_IN_BALANCE -> SCX_RQ_IN_DISPATCH No BPF scheduler reads the flag. The enum autogen headers gain the new name with the old entry retained like other removed enumerators, zero-filling at load time. No functional changes. Signed-off-by: Tejun Heo

sched_ext/scx_flatcg: Fix cvtime true-up on slice expiry

2026-08-15T09:50:47+00:00

fcg_dispatch() true-ups the current cgroup's cvtime when its slice expires or its DSQ runs empty while the slice is still active: __sync_fetch_and_add(&cgc->cvtime_delta, (cpuc->cur_at + cgrp_slice_ns - now) * FCG_HWEIGHT_ONE / (cgc->hweight ?: 1)); The true-up should be actual minus charged: on CNS_EXPIRE, the overrun (now - cur_at - cgrp_slice_ns) should be added; on CNS_EMPTY, the unused portion of the slice should be subtracted. The expression above has the sign inverted, and in the CNS_EXPIRE case now is already past cur_at + cgrp_slice_ns, so the u64 subtraction wraps. The multiplication preserves the two's complement encoding but the unsigned division by hweight destroys it, adding roughly 2^64/hweight per expiry instead of a small correction. Under saturation the hweight budget clamp in cgrp_cap_budget() masks most of the garbage, so the weight distribution barely moves, but the accounting is broken all the same. Compute the delta as a signed value and use fetch_and_add()/fetch_and_sub() so that the dividends stay positive, as BPF division is unsigned. Instrumented the true-up and ran a saturated three-leaf cgroup tree on a 4-CPU VM: without the fix, each expiry added ~5e15 (2^64/hweight territory) to cvtime_delta; with it, the corrections are back to slice scale, with the overrun added and the unused portion subtracted. Fixes: a4103eacc2ab ("sched_ext: Add a cgroup scheduler which uses flattened hierarchy") Suggested-by: Tejun Heo Signed-off-by: Tao Cui Signed-off-by: Tejun Heo

sched_ext: Fix scx_bpf_dsq_move_to_local___v2 compat detection

2026-08-15T09:50:47+00:00

libbpf strips the last ___flavor suffix when resolving kfunc externs, so the bare ___v2 declaration resolves to scx_bpf_dsq_move_to_local, whose BTF proto lacks @enq_flags. The extern never matches, bpf_ksym_exists() returns false on every kernel that has the ___v2 kfunc, and the macro falls back to ___v1, silently dropping @enq_flags. Add the trailing ___compat suffix used by the other versioned externs in this file (scx_bpf_dsq_insert___v2, scx_bpf_reenqueue_local___v2). Any caller passing non-zero @enq_flags through the compat macro silently loses them. Fixes: 860683763ebf ("sched_ext: Add enq_flags to scx_bpf_dsq_move_to_local()") Cc: stable@vger.kernel.org # v7.1+ Assisted-by: Z.ai:glm-5.2 Signed-off-by: fangqiurong Signed-off-by: Tejun Heo

sched_ext: Fix scx_bpf_dsq_reenq___compat kfunc extern prototype

2026-08-14T21:00:56+00:00

scx_bpf_dsq_reenq() is registered with KF_IMPLICIT_ARGS and its kernel BTF prototype omits the trailing bpf_prog_aux argument. The ___compat extern declares the argument explicitly, so libbpf never matches the prototype and the weak extern silently stays unresolved on every kernel. The wrapper always takes the old fallback path, which disables generic reenq users like scx_qmap's lowpri mechanism and fails non-local reenq with "kernel too old" even on kernels that have the kfunc. Drop the explicit aux argument. Also correct the stale v6.20 reference, the kfunc was added in v7.1. Fixes: 9c34c5074d1b ("sched_ext: Introduce scx_bpf_dsq_reenq() for remote local DSQ reenqueue") Cc: stable@vger.kernel.org # v7.1+ Signed-off-by: Tejun Heo

sched_ext/scx_flatcg: expire cached hweights on weight changes

2026-08-14T19:56:28+00:00

fcg_cgroup_set_weight() updates cgc->weight and the parent's child_weight_sum but doesn't bump hweight_gen, so the hweights cached by cgrp_refresh_hweight() stay stale until some task activation bumps the generation. For cgroups whose tasks never go through a 0->n runnable transition (e.g. persistently busy ones), a cpu.weight change never propagates to scheduling at all. Bump hweight_gen on weight changes so the next refresh recomputes with the new weight. Verified on a flatcg VM: a live cpu.weight 100->800 change on a busy cgroup leaves HWT update at 0 and the distribution unchanged; with it, hweight_gen increments and the refresh recomputes. Signed-off-by: Tao Cui Signed-off-by: Tejun Heo

sched_ext: Convert scx_bpf_cid_override() to __arena array arguments

2026-08-12T19:55:33+00:00

scx_bpf_cid_override() predates the cid-form arena transition and takes its arrays as verifier-checked mem+size buffers, forcing scx_qmap to keep the cpu_to_cid and shard_start arrays in writable bss while the rest of its state lives in the arena. Unify on arena arguments before cid-form schedulers start seeing real use. BPF now translates between BPF and kernel arena addresses for __arena arguments. Take the arrays as __arena arguments, with the counts passed in entries. The counts now size the snapshot copies and are bounds-checked before them. scx_qmap moves the arrays into struct qmap_arena. As the arena is mmapped at load, the loader populates them between load and attach instead of before load. The arena argument address translation is currently implemented only on x86-64. Schedulers calling this kfunc load only there for now. Signed-off-by: Tejun Heo

sched_ext: Convert sub-cap kfuncs to __arena cmask arguments

2026-08-12T19:55:33+00:00

The sub-cap kfuncs take their cmask arguments as __ign pointers. The values cross the kfunc boundary as unchecked scalars and scx_cmask_ref_init() rebases them into the arena by hand. BPF now translates between BPF and kernel arena addresses for __arena arguments. Tag the cmask arguments __arena so the kfuncs receive kernel addresses and scx_cmask_ref_init() loses the hand-rolled conversion. The optional denied_out keeps its NULL not-provided signal via __arena__nullable. The mandatory masks use plain __arena. scx_qmap's call sites drop the (void *)(long) casts since the BPF-side declarations type the cmask arguments __arena and take arena pointers directly. The arena argument address translation is currently implemented only on x86-64. Schedulers calling these kfuncs load only there for now. Signed-off-by: Tejun Heo