Messages in this thread | | | Date | Mon, 27 Aug 2007 11:18:02 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] fix bogus hotplug cpu warning |
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On Mon, 27 Aug 2007 16:06:19 +0100 (BST) Hugh Dickins <hugh@veritas.com> wrote:
> Fix bogus DEBUG_PREEMPT warning on x86_64, when cpu brought online after > bootup: current_is_keventd is right to note its use of smp_processor_id > is preempt-safe, but should use raw_smp_processor_id to avoid the warning. > > Signed-off-by: Hugh Dickins <hugh@veritas.com> > > --- 2.6.23-rc3-git10/kernel/workqueue.c 2007-07-26 19:49:58.000000000 +0100 > +++ linux/kernel/workqueue.c 2007-08-26 18:59:16.000000000 +0100 > @@ -635,7 +635,7 @@ int keventd_up(void) > int current_is_keventd(void) > { > struct cpu_workqueue_struct *cwq; > - int cpu = smp_processor_id(); /* preempt-safe: keventd is per-cpu */ > + int cpu = raw_smp_processor_id(); /* preempt-safe: keventd is per-cpu */ > int ret = 0; > > BUG_ON(!keventd_wq);
But lib/smp_processor_id.c:debug_smp_processor_id() does
/* * Kernel threads bound to a single CPU can safely use * smp_processor_id(): */ this_mask = cpumask_of_cpu(this_cpu);
if (cpus_equal(current->cpus_allowed, this_mask)) goto out;
So I assume that this warning was triggering because some non-keventd, non-pinned task is calling current_is_keventd()?
So I agree with the patch, but not with its description. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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