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authorKirill Korotaev <dev@openvz.org>2006-12-10 02:20:11 -0800
committerChris Wright <chrisw@sous-sol.org>2007-02-05 08:31:45 -0800
commit56cf77091500709c99253b305708bc47196f7d21 (patch)
tree5414c3f2ba385a60614dcf24a90b0d21e8173e3f
parent16a2980e7a2d9afe5b6c68c783d025036edcf70e (diff)
[PATCH] move_task_off_dead_cpu() should be called with disabled ints
move_task_off_dead_cpu() requires interrupts to be disabled, while migrate_dead() calls it with enabled interrupts. Added appropriate comments to functions and added BUG_ON(!irqs_disabled()) into double_rq_lock() and double_lock_balance() which are the origin sources of such bugs. Signed-off-by: Kirill Korotaev <dev@openvz.org> Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org> Signed-off-by: Chris Wright <chrisw@sous-sol.org>
-rw-r--r--kernel/sched.c17
1 files changed, 14 insertions, 3 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 0512417de305..5f6939cad314 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1941,6 +1941,7 @@ static void double_rq_lock(struct rq *rq1, struct rq *rq2)
__acquires(rq1->lock)
__acquires(rq2->lock)
{
+ BUG_ON(!irqs_disabled());
if (rq1 == rq2) {
spin_lock(&rq1->lock);
__acquire(rq2->lock); /* Fake it out ;) */
@@ -1980,6 +1981,11 @@ static void double_lock_balance(struct rq *this_rq, struct rq *busiest)
__acquires(busiest->lock)
__acquires(this_rq->lock)
{
+ if (unlikely(!irqs_disabled())) {
+ /* printk() doesn't work good under rq->lock */
+ spin_unlock(&this_rq->lock);
+ BUG_ON(1);
+ }
if (unlikely(!spin_trylock(&busiest->lock))) {
if (busiest < this_rq) {
spin_unlock(&this_rq->lock);
@@ -5050,7 +5056,10 @@ wait_to_die:
}
#ifdef CONFIG_HOTPLUG_CPU
-/* Figure out where task on dead CPU should go, use force if neccessary. */
+/*
+ * Figure out where task on dead CPU should go, use force if neccessary.
+ * NOTE: interrupts should be disabled by the caller
+ */
static void move_task_off_dead_cpu(int dead_cpu, struct task_struct *p)
{
unsigned long flags;
@@ -5170,6 +5179,7 @@ void idle_task_exit(void)
mmdrop(mm);
}
+/* called under rq->lock with disabled interrupts */
static void migrate_dead(unsigned int dead_cpu, struct task_struct *p)
{
struct rq *rq = cpu_rq(dead_cpu);
@@ -5186,10 +5196,11 @@ static void migrate_dead(unsigned int dead_cpu, struct task_struct *p)
* Drop lock around migration; if someone else moves it,
* that's OK. No task can be added to this CPU, so iteration is
* fine.
+ * NOTE: interrupts should be left disabled --dev@
*/
- spin_unlock_irq(&rq->lock);
+ spin_unlock(&rq->lock);
move_task_off_dead_cpu(dead_cpu, p);
- spin_lock_irq(&rq->lock);
+ spin_lock(&rq->lock);
put_task_struct(p);
}