On Thursday 14 June 2007, Ingo Molnar wrote:
>From: Ingo Molnar <[EMAIL PROTECTED]>
>Subject: [patch] sched: fix SysRq-N (normalize RT tasks)
>
>Gene Heskett reported the following problem while testing CFS: SysRq-N
>is not always effective in normalizing tasks back to SCHED_OTHER.
>
>the reason for that turns out to be the following bug:
>normalize_rt_tasks() uses for_each_process() to iterate through all
>tasks in the system. The problem is, this method does not iterate
>through all tasks, it iterates through all thread groups. The proper
>mechanism to enumerate all tasks is to use a do_each_thread() +
>while_each_thread() loop.
>
>obvious bugfix for v2.6.22 inclusion. -stable candidate as well.
>
>Reported-by: Gene Heskett <[EMAIL PROTECTED]>
>Signed-off-by: Ingo Molnar <[EMAIL PROTECTED]>
>---
> kernel/sched.c | 8 +++++---
> 1 file changed, 5 insertions(+), 3 deletions(-)
>
>Index: linux/kernel/sched.c
>===================================================================
>--- linux/kernel/sched.c
>+++ linux/kernel/sched.c
>@@ -7071,12 +7071,13 @@ EXPORT_SYMBOL(__might_sleep);
> void normalize_rt_tasks(void)
> {
> struct prio_array *array;
>- struct task_struct *p;
>+ struct task_struct *g, *p;
> unsigned long flags;
> struct rq *rq;
>
> read_lock_irq(&tasklist_lock);
>- for_each_process(p) {
>+
>+ do_each_thread(g, p) {
> if (!rt_task(p))
> continue;
>
>@@ -7094,7 +7095,8 @@ void normalize_rt_tasks(void)
>
> __task_rq_unlock(rq);
> spin_unlock_irqrestore(&p->pi_lock, flags);
>- }
>+ } while_each_thread(g, p);
>+
> read_unlock_irq(&tasklist_lock);
> }
Ingo: I appended this patch to the cfs-v16 patch for 2.6.22-rc4, and got this
while applying it:
patching file kernel/sched.c
Hunk #1 FAILED at 7071.
Hunk #2 FAILED at 7095.
2 out of 2 hunks FAILED -- saving rejects to file kernel/sched.c.rej
done
--
Cheers, Gene
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
One man tells a falsehood, a hundred repeat it as true.
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