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Subject: Re: posix-cpu-timers revamp
From: Frank Mayhar <fmayhar@google.com>
To: Roland McGrath <roland@redhat.com>
Cc: frank@exit.com, linux-kernel@vger.kernel.org
In-Reply-To: <1207690074.4687.18.camel@bobble.smo.corp.google.com>
References: <bug-9906-10286@http.bugzilla.kernel.org/>
	 <20080206165045.89b809cc.akpm@linux-foundation.org>
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	 <20080207162203.3e3cf5ab@Varda>
	 <alpine.LRH.1.00.0802071040010.29320@mini.warudkars.net>
	 <alpine.LRH.1.00.0802071054160.29320@mini.warudkars.net>
	 <20080207165455.04ec490b@Varda>
	 <alpine.LRH.1.00.0802071100230.29369@mini.warudkars.net>
	 <alpine.LRH.1.00.0802071153130.15220@mini.warudkars.net>
	 <1204314904.4850.23.camel@peace.smo.corp.google.com>
	 <20080304070016.903E127010A@magilla.localdomain>
	 <1204660376.9768.1.camel@bobble.smo.corp.google.com>
	 <20080305040826.D0E6127010A@magilla.localdomain>
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	 <1206380079.21896.20.camel@bobble.smo.corp.google.com>
	 <20080331054404.78CDB26F8E9@magilla.localdomain>
	 <1206995072.14649.41.camel@bobble.smo.corp.google.com>
	 <20080402020707.151E126F8DC@magilla.localdomain>
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Content-Type: text/plain
Organization: Google, Inc.
Date: Tue, 08 Apr 2008 14:52:41 -0700
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On Tue, 2008-04-08 at 14:27 -0700, Frank Mayhar wrote:
> And, you guessed it, the invariant gets violated.  Apparently the passed
> task_struct isn't the same as "current" at this point.
> 
> Any ideas?  Am I checking the wrong thing?  If we're really not updating
> current then the task we are updating could very easily be running
> through __exit_signal() on another CPU.  (And while I wait for your
> response I will of course continue to try to figure this out.)

Found the exception.  do_fork() violates the invariant when it's
cranking up a new process.  Hmmm.
-- 
Frank Mayhar <fmayhar@google.com>
Google, Inc.