The fix below addresses a lockdep warning i triggered with your config.
(You could hit this if you try to use s2ram or hibernation or explicit
CPU hotplug ops.)
Ingo
-------------->
Subject: sched: cpu hotplug fix
From: Ingo Molnar <mingo@xxxxxxx>
Date: Thu Feb 12 11:35:40 CET 2009
rq_attach_root() does a kfree() with the runqueue lock held.
That's not a very wise move, fix it.
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
kernel/sched.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
Index: tip/kernel/sched.c
===================================================================
--- tip.orig/kernel/sched.c
+++ tip/kernel/sched.c
@@ -7619,20 +7619,26 @@ static void free_rootdomain(struct root_
static void rq_attach_root(struct rq *rq, struct root_domain *rd)
{
+ struct root_domain *old_rd = NULL;
unsigned long flags;
spin_lock_irqsave(&rq->lock, flags);
if (rq->rd) {
- struct root_domain *old_rd = rq->rd;
+ old_rd = rq->rd;
if (cpumask_test_cpu(rq->cpu, old_rd->online))
set_rq_offline(rq);
cpumask_clear_cpu(rq->cpu, old_rd->span);
- if (atomic_dec_and_test(&old_rd->refcount))
- free_rootdomain(old_rd);
+ /*
+ * If we dont want to free the old_rt yet then
+ * set old_rd to NULL to skip the freeing later
+ * in this function:
+ */
+ if (!atomic_dec_and_test(&old_rd->refcount))
+ old_rd = NULL;
}
atomic_inc(&rd->refcount);
@@ -7643,6 +7649,9 @@ static void rq_attach_root(struct rq *rq
set_rq_online(rq);
spin_unlock_irqrestore(&rq->lock, flags);
+
+ if (old_rd)
+ free_rootdomain(old_rd);
}
static int __init_refok init_rootdomain(struct root_domain *rd, bool bootmem)
--
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