sched_ext: Fix spurious aborts in scx_bpf_dsq_move() on ownership change races

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scx_dsq_move() verifies that the task belongs to the calling scheduler
before taking any locks and aborts the scheduler on mismatch. The task can
lose the sched association at any point: It can run and fully exit, which
clears the association, or get rehomed to a different sub-sched. Both are
benign races, but the early ownership check escalates them into scheduler
aborts.

Move the ownership check below the cursor-lost check. Every ownership change
dequeues the task first, so a task that is still on the iterated DSQ under
the lock while owned elsewhere indicates a genuine violation and should
abort.

Also fix two stale comments still referencing sched_ext_free(), which has
been renamed to sched_ext_dead().

Fixes: bb4d9fd551 ("sched_ext: scx_dsq_move() should validate the task belongs to the right scheduler")
Signed-off-by: Tejun Heo <tj@kernel.org>

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This commit is contained in:

Tejun Heo 2026-08-21 09:05:52 -10:00

parent 9e8581a090

commit cca061dccf

1 changed files with 13 additions and 8 deletions

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kernel/sched/ext/ext.c

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