From: Christoph Lameter Interrupts must be disabled for request queue locks if we want to run load_balance() with interrupts enabled. Signed-off-by: Christoph Lameter Cc: Peter Williams Cc: Nick Piggin Cc: Christoph Lameter Cc: "Siddha, Suresh B" Cc: "Chen, Kenneth W" Cc: Ingo Molnar Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton --- kernel/sched.c | 11 ++++++----- 1 files changed, 6 insertions(+), 5 deletions(-) diff -puN kernel/sched.c~sched-disable-interrupts-for-locking-in-load_balance kernel/sched.c --- a/kernel/sched.c~sched-disable-interrupts-for-locking-in-load_balance +++ a/kernel/sched.c @@ -2546,8 +2546,6 @@ static inline unsigned long minus_1_or_z /* * Check this_cpu to ensure it is balanced within domain. Attempt to move * tasks if there is an imbalance. - * - * Called with this_rq unlocked. */ static int load_balance(int this_cpu, struct rq *this_rq, struct sched_domain *sd, enum idle_type idle) @@ -2557,6 +2555,7 @@ static int load_balance(int this_cpu, st unsigned long imbalance; struct rq *busiest; cpumask_t cpus = CPU_MASK_ALL; + unsigned long flags; /* * When power savings policy is enabled for the parent domain, idle @@ -2596,11 +2595,13 @@ redo: * still unbalanced. nr_moved simply stays zero, so it is * correctly treated as an imbalance. */ + local_irq_save(flags); double_rq_lock(this_rq, busiest); nr_moved = move_tasks(this_rq, this_cpu, busiest, minus_1_or_zero(busiest->nr_running), imbalance, sd, idle, &all_pinned); double_rq_unlock(this_rq, busiest); + local_irq_restore(flags); /* All tasks on this runqueue were pinned by CPU affinity */ if (unlikely(all_pinned)) { @@ -2617,13 +2618,13 @@ redo: if (unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2)) { - spin_lock(&busiest->lock); + spin_lock_irqsave(&busiest->lock, flags); /* don't kick the migration_thread, if the curr * task on busiest cpu can't be moved to this_cpu */ if (!cpu_isset(this_cpu, busiest->curr->cpus_allowed)) { - spin_unlock(&busiest->lock); + spin_unlock_irqrestore(&busiest->lock, flags); all_pinned = 1; goto out_one_pinned; } @@ -2633,7 +2634,7 @@ redo: busiest->push_cpu = this_cpu; active_balance = 1; } - spin_unlock(&busiest->lock); + spin_unlock_irqrestore(&busiest->lock, flags); if (active_balance) wake_up_process(busiest->migration_thread); _