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Subject: Re: [PATCH -rt 5/5] slub: -rt port
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Oleg Nesterov <oleg@tv-sign.ru>
Cc: linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
       Thomas Gleixner <tglx@linutronix.de>,
       Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
       Steven Rostedt <rostedt@goodmis.org>,
       Christoph Lameter <clameter@sgi.com>
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Date: Sat, 14 Jul 2007 21:49:49 +0200
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On Sat, 2007-07-14 at 23:38 +0400, Oleg Nesterov wrote:
> On 07/14, Peter Zijlstra wrote:

> > Yeah, the function I copied this from: schedule_on_each_cpu() has a
> > comment to that effect.
> 
> Just in case, schedule_on_each_cpu() ptotects cpu_online_map with
> preempt_disable(), its problem is quite different.


I was schedule_on_each_cpu_wq() I copied, and that does not disable
preemption. Also, I'm failing to see how schedule_on_each_cpu() could
work with -rt, since __queue_work() takes a regular spinlock.

> > Any ideas on how to solve this?
> 
> Perhaps slab_cpuup_callback() can take flush_slab_mutex too, in that
> case cpu_online_map will be stable under flush_slab_mutex.

Right, I'll give that a try.