Messages in this thread | | | Date | Sat, 6 Oct 2007 10:54:35 -0700 (PDT) | From | David Rientjes <> | Subject | Re: [PATCH] task containersv11 add tasks file interface fix for cpusets |
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On Sat, 6 Oct 2007, Paul Jackson wrote:
> This isn't working for me. > > The key kernel routine for updating a tasks cpus_allowed > cannot be called while holding a spinlock. > > But the above loop holds a spinlock, css_set_lock, between > the cgroup_iter_start and the cgroup_iter_end. > > I end up generating complaints of: > BUG: scheduling while atomic > when I invoke the set_cpus_allowed() above. > > Should css_set_lock be a mutex? Locking changes like that > can be risky. >
It would probably be better to just save references to the tasks.
struct cgroup_iter it; struct task_struct *p, **tasks; int i = 0;
cgroup_iter_start(cs->css.cgroup, &it); while ((p = cgroup_iter_next(cs->css.cgroup, &it))) { get_task_struct(p); tasks[i++] = p; } cgroup_iter_end(cs->css.cgroup, &it);
while (--i >= 0) { set_cpus_allowed(tasks[i], cs->cpus_allowed); put_task_struct(tasks[i]); }
The getting and putting of the tasks will prevent them from exiting or being deallocated prematurely. But this is also a critical section that will need to be protected by some mutex so it doesn't race with other set_cpus_allowed().
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