Srivatsa Vaddagiri wrote:
> We rely very much on task_cpu(p) to be correct at all times, so that we
> can correctly find the runqueue from which the task has to be removed or
> added to.
>
> There is however one place in the scheduler where this assumption of
> task_cpu(p) being correct is broken. This patch fixes that piece of
> code.
>
> (Thanks to Balbir Singh for pointing this out to me)
>
> Signed-off-by : Srivatsa Vaddagiri <[EMAIL PROTECTED]>
>
Acked-by: Balbir Singh <[EMAIL PROTECTED]>
> ---
> kernel/sched.c | 8 +++++---
> 1 files changed, 5 insertions(+), 3 deletions(-)
>
> Index: current/kernel/sched.c
> ===================================================================
> --- current.orig/kernel/sched.c 2007-06-09 15:07:17.000000000 +0530
> +++ current/kernel/sched.c 2007-06-09 15:07:32.000000000 +0530
> @@ -4624,7 +4624,7 @@
> static int __migrate_task(struct task_struct *p, int src_cpu, int dest_cpu)
> {
> struct rq *rq_dest, *rq_src;
> - int ret = 0;
> + int ret = 0, on_rq;
>
> if (unlikely(cpu_is_offline(dest_cpu)))
> return ret;
> @@ -4640,9 +4640,11 @@
> if (!cpu_isset(dest_cpu, p->cpus_allowed))
> goto out;
>
> - set_task_cpu(p, dest_cpu);
> - if (p->se.on_rq) {
> + on_rq = p->se.on_rq;
> + if (on_rq)
> deactivate_task(rq_src, p, 0);
> + set_task_cpu(p, dest_cpu);
> + if (on_rq) {
> activate_task(rq_dest, p, 0);
> check_preempt_curr(rq_dest, p);
> }
--
Warm Regards,
Balbir Singh
Linux Technology Center
IBM, ISTL
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