From: Linus Torvalds Subject: Re: [PATCH 1/1] x86: fix text_poke Date: Fri, 25 Apr 2008 09:37:46 -0700 (PDT) Message-ID: References: <20080425.021301.193689806.davem@davemloft.net> <1209343883-7991-1-git-send-email-jirislaby@gmail.com> <20080425151931.GA25510@elte.hu> <20080425152650.GA894@elte.hu> <20080425154854.GC3265@one.firstfloor.org> <20080425162215.GA16273@elte.hu> Mime-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Cc: Andi Kleen , Jiri Slaby , David Miller , zdenek.kabelac@gmail.com, rjw@sisk.pl, paulmck@linux.vnet.ibm.com, akpm@linux-foundation.org, linux-ext4@vger.kernel.org, herbert@gondor.apana.org.au, penberg@cs.helsinki.fi, clameter@sgi.com, linux-kernel@vger.kernel.org, Mathieu Desnoyers , pageexec@freemail.hu, "H. Peter Anvin" , Jeremy Fitzhardinge To: Ingo Molnar Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:35769 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760851AbYDYQop (ORCPT ); Fri, 25 Apr 2008 12:44:45 -0400 In-Reply-To: <20080425162215.GA16273@elte.hu> Sender: linux-ext4-owner@vger.kernel.org List-ID: On Fri, 25 Apr 2008, Ingo Molnar wrote: > > hm, right now we've got a debug protection in set_fixmap() to make sure > it's only ever called once. So it's going to be a noisy bootup. (but > it's a warning only) The patch below removes that. No, I think the warning is good, I should have done some kind of clear_fixmap() after doing the mmap. But there was actually a much worse problem with my patch: __set_fixmap() is __init. Which means that my patch was just totally broken. What I really wanted to do was to just follow the page tables and mark it writable temporarily over the whole loop, and get rid of the whole mess. (We'd need to make __set_fixmap() non-init, and probably return the pte_t pointer that it used, so that we could then just use "native_pte_clear()" on the thing after having done the memcpy()). I suspect I should have just kept using vmap(), even if I do dislike just how insanely expensive that likely is. Linus