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Date: Sat, 20 Nov 2004 15:03:17 +1100
From: Nick Piggin <nickpiggin@yahoo.com.au>
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To: William Lee Irwin III <wli@holomorphy.com>
CC: Linus Torvalds <torvalds@osdl.org>, Christoph Lameter <clameter@sgi.com>,
       akpm@osdl.org, Benjamin Herrenschmidt <benh@kernel.crashing.org>,
       Hugh Dickins <hugh@veritas.com>, linux-mm@kvack.org,
       linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: page fault scalability patch V11 [0/7]: overview
References: <Pine.LNX.4.58.0411181715280.834@schroedinger.engr.sgi.com> <419D581F.2080302@yahoo.com.au> <Pine.LNX.4.58.0411181835540.1421@schroedinger.engr.sgi.com> <419D5E09.20805@yahoo.com.au> <Pine.LNX.4.58.0411181921001.1674@schroedinger.engr.sgi.com> <1100848068.25520.49.camel@gaston> <Pine.LNX.4.58.0411190704330.5145@schroedinger.engr.sgi.com> <Pine.LNX.4.58.0411191155180.2222@ppc970.osdl.org> <20041120020306.GA2714@holomorphy.com> <419EBBE0.4010303@yahoo.com.au> <20041120035510.GH2714@holomorphy.com>
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William Lee Irwin III wrote:
> William Lee Irwin III wrote:
> 
>>>Unprivileged triggers for full-tasklist scans are NMI oops material.
> 
> 
> On Sat, Nov 20, 2004 at 02:37:04PM +1100, Nick Piggin wrote:
> 
>>Hang on, let's come back to this...
>>We already have unprivileged do-for-each-thread triggers in the proc
>>code. It's in do_task_stat, even. Rss reporting would basically just
>>involve one extra addition within that loop.
>>So... hmm, I can't see a problem with it.
> 
> 
> /proc/ triggering NMI oopses was a persistent problem even before that
> code was merged. I've not bothered testing it as it at best aggravates it.
> 

It isn't a problem. If it ever became a problem then we can just
touch the nmi oopser in the loop.

> And thread groups can share mm's. do_for_each_thread() won't suffice.
> 

I think it will be just fine.