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Subject: Re: PATCH Multithreaded core dump support for the 2.5.14 (and 15)
	kernel.
From: Robert Love <rml@tech9.net>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: mgross@unix-os.sc.intel.com, Daniel Jacobowitz <dan@debian.org>,
        Andi Kleen <ak@suse.de>, linux-kernel@vger.kernel.org
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Date: 16 May 2002 14:24:39 -0700
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On Thu, 2002-05-16 at 14:32, Alan Cox wrote:
> > For this to happen that semaphore would have to held across schedule()'s.  
> > The ONLY place I've seen that in the kernel is set_CPUs_allowed + 
> > migration_thread.  
>
> The 2.5 kernel is pre-emptible.

Indeed :)

But there is plenty of places in the kernel - sans preemption - where we
sleep while holding a semaphore.  Was that the original question?  If
so, set_cpus_allowed by be one of the few _explicit_ places but we
implicitly sleep holding a semaphore all over.  Heck, we use them for
user-space synchronization.

	Robert Love