sched_ext: Temporarily work around pick_task_scx() being called without balance_scx()

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pick_task_scx() must be preceded by balance_scx() but there currently is a
bug where fair could say yes on balance() but no on pick_task(), which then
ends up calling pick_task_scx() without preceding balance_scx(). Work around
by dropping WARN_ON_ONCE() and ignoring cases which don't make sense.

This isn't great and can theoretically lead to stalls. However, for
switch_all cases, this happens only while a BPF scheduler is being loaded or
unloaded, and, for partial cases, fair will likely keep triggering this CPU.

This will be reverted once the fair behavior is fixed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>

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Tejun Heo 2024-09-06 08:17:09 -10:00

parent 649e980dad

commit da330f5e4c

1 changed files with 16 additions and 1 deletions

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kernel/sched/ext.c

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