linux-kernel - Re: [RFC][PATCH 6/8] mm: handle_speculative

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Message-ID: <alpine.LFD.2.00.1001050802401.3630@localhost.localdomain>
Date:	Tue, 5 Jan 2010 08:10:21 -0800 (PST)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Al Viro <viro@...IV.linux.org.uk>
cc:	Peter Zijlstra <peterz@...radead.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"minchan.kim@...il.com" <minchan.kim@...il.com>,
	cl@...ux-foundation.org,
	"hugh.dickins" <hugh.dickins@...cali.co.uk>,
	Nick Piggin <nickpiggin@...oo.com.au>,
	Ingo Molnar <mingo@...e.hu>
Subject: Re: [RFC][PATCH 6/8] mm: handle_speculative_fault()



On Tue, 5 Jan 2010, Al Viro wrote:
> 
> - a bunch of fs operations done from RCU callbacks.  Including severely
> blocking ones.

Yeah, you're right (and Peter also pointed out the might_sleep). That is 
likely to be the really fundamental issue. 

You _can_ handle it (make the RCU callback just schedule the work instead 
of doing it directly), but it does sound really nasty. I suspect we should 
explore just about any other approach over this one. 

			Linus
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