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Subject[PATCH 1/1] usermodehelper: kill ____call_usermodehelper()->set_cpus_allowed_ptr()
____call_usermodehelper() does set_cpus_allowed_ptr(cpu_all_mask),
this (and the comment) is misleading. We no longer have keventd_wq,
and kmod.c switched to khelper_wq a long ago.

And more importantly, "unlike our parent" is no longer true too,
this thread was created by WQ_UNBOUND worker thread which has the
full ->cpus_allowed mask, so this set_cpus_allowed_ptr() is simply

Perhaps we will change this later, so that userspace can control
the affinity of the usermode helper tasks, but this is yet another
reason to remove this set_cpus_allowed_ptr().

To some degree this also applies to set_user_nice(), but this
patch only updates the comment.

Signed-off-by: Oleg Nesterov <>
kernel/kmod.c | 8 ++------
1 files changed, 2 insertions(+), 6 deletions(-)

diff --git a/kernel/kmod.c b/kernel/kmod.c
index b086006..2fe4544 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -208,13 +208,9 @@ static int ____call_usermodehelper(void *data)
flush_signal_handlers(current, 1);
- /* We can run anywhere, unlike our parent keventd(). */
- set_cpus_allowed_ptr(current, cpu_all_mask);
- * Our parent is keventd, which runs with elevated scheduling priority.
- * Avoid propagating that into the userspace child.
+ * Our parent is a workqueue thread, which can run with elevated
+ * scheduling priority. Avoid propagating that into the userspace.
set_user_nice(current, 0);


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