kernel/git/next/linux-next.git/tools/sched_ext, branch master

Merge branch 'for-next' of https://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext.git

2026-07-15T12:31:33+00:00

Merge branch 'for-next' of https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git

2026-07-15T12:13:46+00:00

tools/sched_ext: scx_qmap: Fix stale API name in comment

2026-07-14T21:40:59+00:00

The comment above dispatch_highpri() still references scx_bpf_dispatch[_vtime]_from_dsq(), which was renamed to scx_bpf_dsq_move[_vtime]() in v6.13 to unload the overloaded "dispatch" verb. The code below already uses the new names; only the comment was left behind during the rename. Fixes: 5cbb302880f5 ("sched_ext: Rename scx_bpf_dispatch[_vtime]_from_dsq*() -> scx_bpf_dsq_move[_vtime]*()") Signed-off-by: Liang Luo Signed-off-by: Tejun Heo

tools/sched_ext: scx_qmap - Add sub-sched cap fault injection

2026-07-14T08:18:44+00:00

Add a fault-injection mode to the scx_qmap sub-scheduler that deliberately dispatches one of its own tasks to a cid it does not hold. The kernel cap check must reject it and re-enqueue with SCX_TASK_REENQ_CAP, so the nr_inject_attempts counter tracks nr_reenq_cap one to one, exercising the delivery-time cap enforcement. Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi

tools/sched_ext: scx_qmap - Expand hierarchical sub-scheduling

2026-07-14T08:18:44+00:00

sched_ext sub-scheduling began as dispatch delegation only: a parent could call into a child cgroup sub-scheduler's ops.dispatch() from its own dispatch path, but could not delegate cpus to the child for enqueue and the other paths. sched_ext has since gained cap-based cid delegation, where a parent grants and revokes a child's per-cid caps. Expand scx_qmap to demonstrate it. scx_qmap can now delegate the cids it holds exclusively, split among itself and its children by cpu.weight. Each gets the floor of its share as dedicated cids. The leftover from rounding forms a shared pool, round-robined among them as an ENQ_IMMED time-share. This shape is deliberate. Exclusive cids exercise the basic grant and revoke of ownership, and the shared pool exercises time-sharing one cid across several schedulers. The implemented policy is impractical, but it covers most of what a practical sub-scheduler would need without overcomplicating qmap. Delegation nests. A cid a node receives from its parent only as a round-robin share stays self-local and is never re-delegated. A node left with no exclusive cid, e.g. after its cpus went offline, evicts its children. v5: Highpri dispatch masked with self_cids, single-read dispatch cgroup_id, feed_weights race comment. (sashiko AI) v4: Track all idle cids and mask with self_cids at the dispatch pick, dropping the reseed. (sashiko AI) v3: Dispatch IMMED flags, repartition accounting order, partition-input snapshot. (sashiko AI) v2: Use __sync_fetch_and_add() for the shared nr_dsps counter. (sashiko AI) Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi

tools/sched_ext: Add three-mask cmask intersection iterator

2026-07-14T08:18:44+00:00

Add cmask_next_and2_set() and its round-robin wrap, extending cmask_next_and_set() to a three-mask intersection: the next cid set in all three masks at or after @start. A caller iterating the intersection of three cmasks can then scan it in one pass, folding the third mask into the word-level AND rather than skipping non-members one candidate at a time. Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi

sched_ext: Add scx_bpf_sub_kill() to evict a child sub-scheduler

2026-07-14T08:18:44+00:00

A cid-form scheduler can grant caps to and revoke them from its child sub-schedulers but has no way to tear one down. Add scx_bpf_sub_kill() to evict a direct child with a printf-style reason that reaches the child's scx_exit_info. No exit code is taken because the child is a separate scheduler whose exit-code semantics the parent cannot know. The child and its subtree are disabled through the usual async path under a new exit kind, SCX_EXIT_PARENT_KILL. The bstr formatting infrastructure in ext.c is exposed through internal.h with scx_ prefixes so the kfunc, which lives in sub.c, can format the reason. Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi

sched_ext: Add per-shard cap delegation for sub-schedulers

2026-07-14T08:18:43+00:00

Caps are per-cid permissions parents delegate to direct children via scx_bpf_sub_grant() / scx_bpf_sub_revoke(). A child's cap set is always a subset of its parent's. Sub-scheds check their caps locally, and cross-sched communication is needed only when the delegation set itself changes. Caps will be used to implement sub-sched scheduling on the enqueue path. Picking a cid for a task at a leaf depends on which cids the leaf is allowed to use, and resolving that programmatically on every enqueue would mean a cross-sched round-trip call chain, possibly retrying if the request can't be granted as-is. The dispatch path is different - it runs as top-down recursion via scx_bpf_sub_dispatch(). Locking is per shard. cid space is split into shards, and each sub-sched has its own pshard->lock for each shard. Operations are broken up on shard boundaries. Different shards never contend. Shards are expected to be topology-aligned and likely to serve as the locality unit when cids are allocated to schedulers, so per-shard lock granularity scales naturally with the allocation pattern. This patch adds the framework with a single dummy cap. Real caps land in later patches. The enable path is reordered for pshards. scx_arena_pool_init() moves ahead of scx_link_sched() so the pshards are allocated before the sched becomes reachable - scx_alloc_pshards() skips allocation when the arena pool isn't initialized. - scx_bpf_sub_grant(): Per-cid all-or-nothing grant to direct child. - scx_bpf_sub_revoke(): Clear caps on @cmask across @child and its subtree. - scx_bpf_sub_caps(): Lockless snapshot of caps on a cid range. /sys/kernel/sched_ext/SCHED/caps shows the caps each scheduler currently holds. v4: Move the pshard[] full build/publish and the err_disable scx_error() recording to earlier patches. (sashiko AI) v3: Build pshard[] fully before publishing it, read it with READ_ONCE. (sashiko AI) v2: Validate ops before scx_link_sched() publishes the sub. (sashiko AI) Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi

sched_ext: Add shard boundaries to scx_bpf_cid_override()

2026-07-14T08:18:42+00:00

An overridden cid mapping invalidates the auto-generated shard layout, so the override call has to provide both. Extend scx_bpf_cid_override() with a shard_start[] array that lists the first cid of each shard (starting at 0, strictly increasing, last shard implicitly extends to num_possible_cpus()). A scheduler that wants only custom shards with the auto-generated cid mapping can read the current mapping and pass it back unchanged. Overridden shards can span NUMA nodes, so scx_shard_node[] is rebuilt by majority count: each shard is assigned to the node that owns the most cpus in it. v2: Snapshot the caller's cpu_to_cid/shard_start arrays before validating. (sashiko AI) Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi

sched_ext: Add ops.init_cids() to finalize the cid layout before init

2026-07-14T08:18:42+00:00

A cid-form scheduler that calls scx_bpf_cid_override() to install a custom cid layout can only do so from ops.init(). Enable-path setup that depends on the cid layout thus has to run after ops.init(), and ops.init() itself can't use anything derived from the final layout, which turned out to be too restrictive. Add an ops.init_cids() callback dedicated to finalizing the cid layout. It runs before the rest of the enable-path setup, so the final layout is in effect for everything that follows including ops.init(), which now runs after the arena pool and cmask scratch allocations. scx_bpf_cid_override() is restricted to ops.init_cids() at load time. It sits in a kfunc set gated by SCX_KF_ALLOW_INIT_CIDS, a flag set only on the init_cids op, so the verifier rejects a call from any other context. The runtime root-only check is dropped as ops.init_cids() only runs during root enable. The qmap demo moves its override into a dedicated qmap_init_cids() and, while at it, introduces an enum for the cid override modes instead of hard-coded integers. Signed-off-by: Tejun Heo Reviewed-by: Andrea Righi