Messages in this thread | | | Subject | Re: [PATCH] kernel/sched: Fix sched_fork() access an invalid sched_task_group | From | Zhang Qiao <> | Date | Wed, 8 Sep 2021 19:32:06 +0800 |
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On 2021/9/8 1:01, Tejun Heo wrote: > Hello, > > On Thu, Sep 02, 2021 at 03:42:15PM +0800, Zhang Qiao wrote: >> I checked the code again. >> I don't quite understand what you said, if the child be moved between >> cgroup_post_fork() and sched_post_sched(), what problems might it cause? > > cgroup_post_fork() is where the child's creation is committed from cgroup's > POV, so it'd be migrating cgroups before the initial creation is finished. >>From glancing, looks like it'll break css_set task counts to begin with. > This violates the basic assumptions and can cause critical failures in > subtle ways. The would replace one subtle race with a possibly worse one.
Hello,
I will update this patch by following the steps below: 1)rename cgroup_subsys->fork() to cgroup_subsys->post_fork(); 2)add cgroup_subsys->fork() and the cpu_cgroup_fork() callback like this:
void cpu_cgroup_fork(struct task_struct *task) { .... p->sched_task_group = task_group(current); __set_task_cpu(p, smp_processor_id()); if (p->sched_class->task_fork) p->sched_class->task_fork(p); ....
3)call cgroup_subsys->fork() after cgroup_can_fork().
Do you have any suggestion? thanks.
Zhang Qiao
> > Thanks. >
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