Messages in this thread Patch in this message | ![/](/images/icornerl.gif) | | Subject | Re: [RFC/RFT PATCH v3] sched: automated per tty task groups | From | Mike Galbraith <> | Date | Thu, 11 Nov 2010 15:20:00 -0700 |
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On Thu, 2010-11-11 at 21:27 +0100, Oleg Nesterov wrote: > I didn't read this patch carefully (yet) but, > > On 11/11, Mike Galbraith wrote: > > > > @@ -2569,6 +2576,7 @@ void sched_fork(struct task_struct *p, i > > * Silence PROVE_RCU. > > */ > > rcu_read_lock(); > > + autogroup_fork(p); > > Surely this doesn't need rcu.
No, it was just a convenient spot.
> But the real problem is that copy_process() can fail after that, > and in this case we have the unbalanced kref_get().
Memory leak, will fix.
> > +++ linux-2.6.36.git/kernel/exit.c > > @@ -174,6 +174,7 @@ repeat: > > write_lock_irq(&tasklist_lock); > > tracehook_finish_release_task(p); > > __exit_signal(p); > > + sched_autogroup_exit(p); > > This doesn't look right. Note that "p" can run/sleep after that > (or in parallel), set_task_rq() can use the freed ->autogroup.
So avoiding refcounting rcu released task_group backfired. Crud.
> Btw, I can't apply this patch...
It depends on the patch below from Peter, or manual fixup.
Subject: sched, cgroup: Fixup broken cgroup movement From: Peter Zijlstra <a.p.zijlstra@chello.nl> Date: Fri Oct 15 15:24:15 CEST 2010
Reported-by: Dima Zavin <dima@android.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> --- include/linux/sched.h | 2 +- kernel/sched.c | 8 ++++---- kernel/sched_fair.c | 25 +++++++++++++++++++------ 3 files changed, 24 insertions(+), 11 deletions(-)
Index: linux-2.6.36.git/kernel/sched.c =================================================================== --- linux-2.6.36.git.orig/kernel/sched.c +++ linux-2.6.36.git/kernel/sched.c @@ -8297,12 +8297,12 @@ void sched_move_task(struct task_struct if (unlikely(running)) tsk->sched_class->put_prev_task(rq, tsk); - set_task_rq(tsk, task_cpu(tsk)); - #ifdef CONFIG_FAIR_GROUP_SCHED - if (tsk->sched_class->moved_group) - tsk->sched_class->moved_group(tsk, on_rq); + if (tsk->sched_class->task_move_group) + tsk->sched_class->task_move_group(tsk, on_rq); + else #endif + set_task_rq(tsk, task_cpu(tsk)); if (unlikely(running)) tsk->sched_class->set_curr_task(rq); Index: linux-2.6.36.git/include/linux/sched.h =================================================================== --- linux-2.6.36.git.orig/include/linux/sched.h +++ linux-2.6.36.git/include/linux/sched.h @@ -1072,7 +1072,7 @@ struct sched_class { struct task_struct *task); #ifdef CONFIG_FAIR_GROUP_SCHED - void (*moved_group) (struct task_struct *p, int on_rq); + void (*task_move_group) (struct task_struct *p, int on_rq); #endif }; Index: linux-2.6.36.git/kernel/sched_fair.c =================================================================== --- linux-2.6.36.git.orig/kernel/sched_fair.c +++ linux-2.6.36.git/kernel/sched_fair.c @@ -3824,13 +3824,26 @@ static void set_curr_task_fair(struct rq } #ifdef CONFIG_FAIR_GROUP_SCHED -static void moved_group_fair(struct task_struct *p, int on_rq) +static void task_move_group_fair(struct task_struct *p, int on_rq) { - struct cfs_rq *cfs_rq = task_cfs_rq(p); - - update_curr(cfs_rq); + /* + * If the task was not on the rq at the time of this cgroup movement + * it must have been asleep, sleeping tasks keep their ->vruntime + * absolute on their old rq until wakeup (needed for the fair sleeper + * bonus in place_entity()). + * + * If it was on the rq, we've just 'preempted' it, which does convert + * ->vruntime to a relative base. + * + * Make sure both cases convert their relative position when migrating + * to another cgroup's rq. This does somewhat interfere with the + * fair sleeper stuff for the first placement, but who cares. + */ + if (!on_rq) + p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime; + set_task_rq(p, task_cpu(p)); if (!on_rq) - place_entity(cfs_rq, &p->se, 1); + p->se.vruntime += cfs_rq_of(&p->se)->min_vruntime; } #endif @@ -3882,7 +3895,7 @@ static const struct sched_class fair_sch .get_rr_interval = get_rr_interval_fair, #ifdef CONFIG_FAIR_GROUP_SCHED - .moved_group = moved_group_fair, + .task_move_group = task_move_group_fair, #endif };
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