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Subject: Re: [PATCH 01/13] powerpc: Add rcu_read_lock() to gup_fast()
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From: James Bottomley <James.Bottomley@HansenPartnership.com>
To: paulmck@linux.vnet.ibm.com
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Date: Sat, 17 Apr 2010 22:06:36 -0500
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On Fri, 2010-04-16 at 09:45 -0700, Paul E. McKenney wrote:
> o	mutex_lock(): Critical sections need not guarantee
> 	forward progress, as general blocking is permitted.

This isn't quite right.  mutex critical sections must guarantee eventual
forward progress against the class of other potential acquirers of the
mutex otherwise the system will become either deadlocked or livelocked.

James