From e9dd685ce81815811fb4da72e6ab10a694ac8468 Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Tue, 27 May 2014 17:02:04 -0400 Subject: [PATCH] sched/numa: Fix use of spin_{un}lock_irq() when interrupts are disabled As Peter Zijlstra told me, we have the following path: do_exit() exit_itimers() itimer_delete() spin_lock_irqsave(&timer->it_lock, &flags); timer_delete_hook(timer); kc->timer_del(timer) := posix_cpu_timer_del() put_task_struct() __put_task_struct() task_numa_free() spin_lock(&grp->lock); Which means that task_numa_free() can be called with interrupts disabled, which means that we should not be using spin_lock_irq() but spin_lock_irqsave() instead. Otherwise we are enabling interrupts while holding an interrupt unsafe lock! Signed-off-by: Steven Rostedt Signed-off-by: Peter Zijlstra Cc: Thomas Gleixner Cc: Mike Galbraith Cc: Eric Dumazet Cc: Linus Torvalds Link: http://lkml.kernel.org/r/20140527182541.GH11096@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- kernel/sched/fair.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 0fdb96de81a5..b4768c069392 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1707,18 +1707,19 @@ no_join: void task_numa_free(struct task_struct *p) { struct numa_group *grp = p->numa_group; - int i; void *numa_faults = p->numa_faults_memory; + unsigned long flags; + int i; if (grp) { - spin_lock_irq(&grp->lock); + spin_lock_irqsave(&grp->lock, flags); for (i = 0; i < NR_NUMA_HINT_FAULT_STATS * nr_node_ids; i++) grp->faults[i] -= p->numa_faults_memory[i]; grp->total_faults -= p->total_numa_faults; list_del(&p->numa_entry); grp->nr_tasks--; - spin_unlock_irq(&grp->lock); + spin_unlock_irqrestore(&grp->lock, flags); rcu_assign_pointer(p->numa_group, NULL); put_numa_group(grp); } -- 2.20.1