Messages in this thread | | | Date | Sat, 6 Oct 2007 13:53:53 -0700 | From | "Paul Menage" <> | Subject | Re: [PATCH] task containersv11 add tasks file interface fix for cpusets |
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On 10/6/07, Paul Jackson <pj@sgi.com> 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.
css_set_lock is an rwlock currently; I'd rather not turn it into an rw mutex since there are places that it gets taken where we can't afford to sleep.
> > Or perhaps there should be another callback, called only by > attach() requests back to the same group. Likely cpusets would > be the only subsystem interested in plugging that callback. > > That, or my original patch, which calls the attach routine > even if re-attaching to the current cgroup ...
I'd prefer David's solution of grabbing references to tasks during the iteration and then doing set_cpus_allowed outside the tasklist_lock.
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