[patch 2/2] sched: fix nr_uninterruptible accounting of frozen tasks really

Nathan Lynch ntl at pobox.com
Fri Jul 17 13:54:25 PDT 2009

On Fri, 2009-07-17 at 12:25 +0000, Thomas Gleixner wrote:
> commit e3c8ca8336 (sched: do not count frozen tasks toward load) broke
> the nr_uninterruptible accounting on freeze/thaw. On freeze the task
> is excluded from accounting with a check for (task->flags &
> PF_FROZEN), but that flag is cleared before the task is thawed. So
> while we prevent that the freezing task with state
> TASK_UNINTERRUPTIBLE is accounted to nr_uninterruptible we decrement
> nr_uninterruptible on thaw.
> Use a separate flag which is handled by the freezing task itself. Set
> it before calling the scheduler with TASK_UNINTERRUPTIBLE state and
> clear it after we return from frozen state.

Thanks for the fix, and sorry for the regression.  I'll test this early
next week but I don't anticipate any problems for the use case the
original patch was addressing.

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