Subject: Re: [PATCH 1/3] [PATCH i386] during VM oom condition, kill all
	threads in process group
From: Will Schmidt <will_schmidt@vnet.ibm.com>
Reply-To: will_schmidt@vnet.ibm.com
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linuxppc-dev@ozlabs.org, "Eric W. Biederman" <ebiederm@xmission.com>,
       Oleg Nesterov <oleg@tv-sign.ru>, Anton Blanchard <anton@samba.org>,
       linux-kernel@vger.kernel.org
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Organization: IBM
Date: Fri, 08 Jun 2007 16:12:26 -0500
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On Fri, 2007-06-08 at 12:32 -0700, Andrew Morton wrote:
> On Fri, 08 Jun 2007 14:19:18 -0500
> Will Schmidt <will_schmidt@vnet.ibm.com> wrote:
> 
> > > > > zap_other_threads() requires tasklist_lock.
> > 

> In fact, it's probably the case that rcu_read_lock() is now sufficient
> locking coverage for zap_other_threads() (cc's people).
> 
> It had better be, because do_group_exit() forgot to take tasklist_lock.  It
> is perhaps relying upon spin_lock()'s hidden rcu_read_lock() properties
> without so much as a code comment, which would be somewhat nasty of it.

> You could perhaps just call do_group_exit() from within the fault
> handler,
> btw.

Yup, so looks like I can actually replace the existing do_exit() call
with do_group_exit().   I'll sit on this for a bit to give other folks a
chance to comment on which lock call is sufficient, read_lock() or
rcu_read_lock(), etc;  and do_group_exit()'s issue with taking
tasklist_lock. 

Thanks,

-Will

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