sched_ext: A fix for v6.14-rc4

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pick_task_scx() has a workaround to avoid stalling when the fair class's
 balance() says yes but pick_task() says no. The workaround was incorrectly
 deciding to keep the prev taks running if the task is on SCX even when the
 task is in a sleeping state, which can lead to several confusing failure
 modes. Fix it by testing the prev task is currently queued on SCX instead.
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Merge tag 'sched_ext-for-6.14-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext

Pull sched_ext fix from Tejun Heo:
 "pick_task_scx() has a workaround to avoid stalling when the fair
  class's balance() says yes but pick_task() says no.

  The workaround was incorrectly deciding to keep the prev taks running
  if the task is on SCX even when the task is in a sleeping state, which
  can lead to several confusing failure modes.

  Fix it by testing the prev task is currently queued on SCX instead"

* tag 'sched_ext-for-6.14-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
  sched_ext: Fix pick_task_scx() picking non-queued tasks when it's called without balance()

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Linus Torvalds 2025-02-26 14:13:11 -08:00

parent 5394eea106 8fef0a3b17

commit e6d3c4e535

1 changed files with 7 additions and 4 deletions

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kernel/sched/ext.c

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