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sched: fix nr_uninterruptible accounting of frozen tasks really

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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 task with state TASK_UNINTERRUPTIBLE
is accounted to nr_uninterruptible on freeze 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.

Cc: <stable@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Thomas Gleixner
2009-07-17 14:15:47 +02:00
parent a468d38934
commit 6301cb95c1
2 changed files with 9 additions and 1 deletions
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7
kernel/freezer.c
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@@ -44,12 +44,19 @@ void refrigerator(void)
recalc_sigpending(); /* We sent fake signal, clean it up */
spin_unlock_irq(&current->sighand->siglock);
/* prevent accounting of that task to load */
current->flags |= PF_FREEZING;
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (!frozen(current))
break;
schedule();
}
/* Remove the accounting blocker */
current->flags &= ~PF_FREEZING;
pr_debug("%s left refrigerator\n", current->comm);
__set_current_state(save);
}