The call_usermodehelper_exec_[a]sync() kernel threads are created by unbound workqueues precisely because we want them to be affine to all CPUs, irrespective of any call_usermodehelper() caller with possibly reduced CPU affinity. So this explicit all-CPUs wide affinity forcing is useless.
Not only useless it even adds disturbance on isolated CPUs in nohz full configurations where users set the unbound workqueues low level cpumask to a reduced set in order to execute non-user-critical work on housekeeping dedicated CPUs. This reduced affinity is naturally inherited to usermodehelper kernel threads but the explicit call to set_cpus_allowed_ptr() breaks that. So just remove it. Cc: Rik van Riel <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Christoph Lameter <[email protected]> Signed-off-by: Frederic Weisbecker <[email protected]> --- kernel/kmod.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/kernel/kmod.c b/kernel/kmod.c index 9ffb24c..d190178 100644 --- a/kernel/kmod.c +++ b/kernel/kmod.c @@ -221,9 +221,6 @@ static int call_usermodehelper_exec_async(void *data) flush_signal_handlers(current, 1); spin_unlock_irq(¤t->sighand->siglock); - /* We can run anywhere, unlike our parent (unbound workqueue). */ - set_cpus_allowed_ptr(current, cpu_all_mask); - /* * Our parent is the unbound workqueue, which runs with elevated * scheduling priority. Avoid propagating that into the userspace child. -- 2.1.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
