linux-kernel - Re: [patch 1/2] x86_64 page fault NMI-safe

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Message-ID: <4C3E490B.4000702@gmail.com>
Date:	Thu, 15 Jul 2010 01:32:27 +0200
From:	Tejun Heo <htejun@...il.com>
To:	"H. Peter Anvin" <hpa@...or.com>
CC:	Andi Kleen <andi@...stfloor.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Ingo Molnar <mingo@...e.hu>,
	LKML <linux-kernel@...r.kernel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Steven Rostedt <rostedt@...tedt.homelinux.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Christoph Hellwig <hch@....de>, Li Zefan <lizf@...fujitsu.com>,
	Lai Jiangshan <laijs@...fujitsu.com>,
	Johannes Berg <johannes.berg@...el.com>,
	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
	Arnaldo Carvalho de Melo <acme@...radead.org>,
	Tom Zanussi <tzanussi@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	"Frank Ch. Eigler" <fche@...hat.com>
Subject: Re: [patch 1/2] x86_64 page fault NMI-safe

Hello,

On 07/14/2010 10:08 PM, H. Peter Anvin wrote:
>> I suspect the low level per cpu allocation functions should 
>> just call it.
>>
> 
> Yes, specifically the point at which we allocate new per cpu memory
> blocks.

We can definitely do that but walking whole page table list is too
heavy to do automatically at that level especially when all users
other than NMI would be fine w/ the default lazy approach.  If Linus'
approach doesn't pan out, I think the right thing to do would be
adding a wrapper to vmalloc_sync_all() and let perf code call it after
percpu allocation.

Thanks.

-- 
tejun
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