drain_local_pages_wq() disables preemption to avoid CPU migration during CPU hotplug and can't use cpus_read_lock(). Using migrate_disable() works here, too. The scheduler won't take the CPU offline until the task left the migrate-disable section. The problem with disabled preemption here is that drain_local_pages() acquires locks which are turned into sleeping locks on PREEMPT_RT and can't be acquired with disabled preemption. Use migrate_disable() in drain_local_pages_wq(). Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> --- mm/page_alloc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3147,9 +3147,9 @@ static void drain_local_pages_wq(struct * cpu which is alright but we also have to make sure to not move to * a different one. */ - preempt_disable(); + migrate_disable(); drain_local_pages(drain->zone); - preempt_enable(); + migrate_enable(); } /*
