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An rq-level flag > only works while dispatches and picks pair up one to one, which core > scheduling breaks: selections interleave through dispatch's lock drops and a > pick can consume a stale flag, keeping a task that has since been dequeued. > Fixing core scheduling support requires the decision to travel with the > dispatch that made it. Make scx_dispatch_sched() and balance_one() return an > explicit verdict instead. > > Also factor the pick-side invocation, its follow-up queueing and the > post-dispatch checks out of do_pick_task_scx() into dispatch_pick(). No > functional changes intended. > > Fixes: 4c95380701f5 ("sched/ext: Fold balance_scx() into pick_task_scx()") > Cc: stable@vger.kernel.org # v6.19+ > Signed-off-by: Tejun Heo > --- ... > diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h > index 450b6a04669f..14c2df6fd9af 100644 > --- a/kernel/sched/sched.h > +++ b/kernel/sched/sched.h > @@ -784,7 +784,6 @@ enum scx_rq_flags { > */ > SCX_RQ_ONLINE = 1 << 0, > SCX_RQ_CAN_STOP_TICK = 1 << 1, > - SCX_RQ_BAL_KEEP = 1 << 3, /* balance decided to keep current */ > SCX_RQ_CLK_VALID = 1 << 5, /* RQ clock is fresh and valid */ > SCX_RQ_BAL_CB_PENDING = 1 << 6, /* must queue a cb after dispatching */ Should we update also tools/sched_ext/include/scx/*.h to remove SCX_RQ_BAL_KEEP? Thanks, -Andrea