[patch] Real-Time Preemption, -RT-2.6.10-rc2-mm3-V0.7.32-12

[Ingo Molnar]

* Ingo Molnar <mingo@xxxxxxx> wrote:

> SLAB draining was an oversight - it's mainly called when there is VM
> pressure (which is not a stricly necessary feature, so i disabled it),
> but i forgot about the module-unload case where it's a correctness
> feature. Your patch is a good starting point, i'll try to fix it on
> SMP too.

here's the full patch against a recent tree, or download the -32-12
patch from the usual place:

    http://redhat.com/~mingo/realtime-preempt/

Rui, Gene, does this fix the module unload crash you are seeing?

	Ingo

--- linux/mm/slab.c.orig
+++ linux/mm/slab.c
@@ -1509,22 +1509,26 @@ static void smp_call_function_all_cpus(v
 static void drain_array_locked(kmem_cache_t* cachep,
 				struct array_cache *ac, int force);
 
-#ifndef CONFIG_PREEMPT_RT
-/*
- * Executes in an IRQ context:
- */
-static void do_drain(void *arg)
+static void do_drain_cpu(kmem_cache_t *cachep, int cpu)
 {
-	kmem_cache_t *cachep = (kmem_cache_t*)arg;
 	struct array_cache *ac;
-	int cpu = smp_processor_id();
 
 	check_irq_off();
-	ac = ac_data(cachep, cpu);
+
 	spin_lock(&cachep->spinlock);
+	ac = ac_data(cachep, cpu);
 	free_block(cachep, &ac_entry(ac)[0], ac->avail);
-	spin_unlock(&cachep->spinlock);
 	ac->avail = 0;
+	spin_unlock(&cachep->spinlock);
+}
+
+#ifndef CONFIG_PREEMPT_RT
+/*
+ * Executes in an IRQ context:
+ */
+static void do_drain(void *arg)
+{
+	do_drain_cpu((kmem_cache_t*)arg, smp_processor_id());
 }
 #endif
 
@@ -1532,6 +1536,11 @@ static void drain_cpu_caches(kmem_cache_
 {
 #ifndef CONFIG_PREEMPT_RT
 	smp_call_function_all_cpus(do_drain, cachep);
+#else
+	int cpu;
+
+	for_each_online_cpu(cpu)
+		do_drain_cpu(cachep, cpu);
 #endif
 	check_irq_on();
 	spin_lock_irq(&cachep->spinlock);
-
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