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

[Gene Heskett]

On Thursday 09 December 2004 08:13, Ingo Molnar wrote:
>* 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?

I'm still on -9 here Ingo, and I just rmmod'ed eeprom with no ill
effects.  I'd built -10 last night but as kde was trying to build,
didn't reboot.  I just got -12, so I'll do it and reboot to it next.

Or am I the wrong Gene?

>
> 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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-- 
Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
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Copyright 2004 by Maurice Eugene Heskett, all rights reserved.

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