sched_ext: Call ops.dequeue() when a task arrives on a remote local DSQ

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When a task in the BPF scheduler's custody is moved to another CPU's
local DSQ, ops.dequeue() is only called once the task is picked for
execution, from set_next_task_scx() with SCX_DEQ_CORE_SCHED_EXEC, even
though no core-sched pick took place. It should instead be called
without flags when the task is inserted into the destination DSQ, as it
is for same-rq dispatches.

move_remote_task_to_local_dsq() sets p->scx.sticky_cpu across the
migration so that deactivate_task() on the source rq doesn't end custody.
Since commit b75aaea24c ("sched_ext: Properly mark SCX-internal
migrations via sticky_cpu"), enqueue_task_scx() only clears it after
inserting the task, so task_leave_custody() still sees the migration in
progress and skips the custody exit.

Clear p->scx.sticky_cpu as soon as enqueue_task_scx() has read it, as
was done before that commit. The source side is unaffected.

Fixes: ebf1ccff79 ("sched_ext: Fix ops.dequeue() semantics")
Cc: stable@vger.kernel.org # 7.1.x: 18d62044cd: sched_ext: Preserve rq tracking across local DSQ dispatch
Cc: stable@vger.kernel.org # 7.1.x
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Assisted-by: Claude:claude-opus-5.5
Signed-off-by: Kuba Piecuch <jpiecuch@google.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

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Kuba Piecuch 2026-09-30 14:23:58 +00:00 • committed by Tejun Heo

parent d35a535d3e

commit af701b8d32

1 changed files with 7 additions and 3 deletions

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kernel/sched/ext/ext.c

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