| Message ID | 1277199893.1875.690.camel@laptop |
|---|---|
| State | Not Applicable, archived |
| Delegated to: | David Miller |
| Headers | show |
Peter Zijlstra wrote: > Paul Menage, Li Zefan, any comments? > > > --- > Because cgroup_fork() is ran before sched_fork() [ from copy_process() ] > and the child's pid is not yet visible the child is pinned to its > cgroup. Therefore we can silence this warning. > The explanation is correct. We silenced another warning according to the same reason. See freezer_fork() in kernel/cgroup_freezer.c > A nicer solution would be moving cgroup_fork() to right after > dup_task_struct() and exclude PF_STARTING from task_subsys_state(). > Seems PF_STARTING is set in copy_flags(), that's after dup_task_struct() and before cgroup_fork(). But it's cleared after copy_process(), that's after the task is linked into tasklist, so this doesn't seem work... > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> For this patch: Reviewed-by: Li Zefan <lizf@cn.fujitsu.com> > --- > kernel/sched.c | 9 +++++++++ > 1 files changed, 9 insertions(+), 0 deletions(-) > > diff --git a/kernel/sched.c b/kernel/sched.c > index b697606..2e79518 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -2561,7 +2561,16 @@ void sched_fork(struct task_struct *p, int clone_flags) > if (p->sched_class->task_fork) > p->sched_class->task_fork(p); > > + /* > + * The child is not yet in the pid-hash so no cgroup attach races, > + * and the cgroup is pinned to this child due to cgroup_fork() > + * is ran before sched_fork(). > + * > + * Silence PROVE_RCU. > + */ > + rcu_read_lock(); > set_task_cpu(p, cpu); > + rcu_read_unlock(); > > #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) > if (likely(sched_info_on())) > > > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/kernel/sched.c b/kernel/sched.c index b697606..2e79518 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -2561,7 +2561,16 @@ void sched_fork(struct task_struct *p, int clone_flags) if (p->sched_class->task_fork) p->sched_class->task_fork(p); + /* + * The child is not yet in the pid-hash so no cgroup attach races, + * and the cgroup is pinned to this child due to cgroup_fork() + * is ran before sched_fork(). + * + * Silence PROVE_RCU. + */ + rcu_read_lock(); set_task_cpu(p, cpu); + rcu_read_unlock(); #if defined(CONFIG_SCHEDSTATS) || defined(CONFIG_TASK_DELAY_ACCT) if (likely(sched_info_on()))
Paul Menage, Li Zefan, any comments? --- Because cgroup_fork() is ran before sched_fork() [ from copy_process() ] and the child's pid is not yet visible the child is pinned to its cgroup. Therefore we can silence this warning. A nicer solution would be moving cgroup_fork() to right after dup_task_struct() and exclude PF_STARTING from task_subsys_state(). Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> --- kernel/sched.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html