From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759018AbYJVT23 (ORCPT ); Wed, 22 Oct 2008 15:28:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752109AbYJVT2U (ORCPT ); Wed, 22 Oct 2008 15:28:20 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:53801 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751535AbYJVT2T (ORCPT ); Wed, 22 Oct 2008 15:28:19 -0400 Date: Wed, 22 Oct 2008 12:26:54 -0700 From: Andrew Morton To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, fweisbec@gmail.com, sagar.abhishek@gmail.com, davem@davemloft.net, tglx@linutronix.de, peterz@infradead.org, torvalds@linux-foundation.org, srostedt@redhat.com Subject: Re: [PATCH 04/11] ftrace: comment arch ftrace code Message-Id: <20081022122654.744d9e85.akpm@linux-foundation.org> In-Reply-To: References: <20081022184313.179487464@goodmis.org> <20081022185136.134729572@goodmis.org> <20081022120951.11665534.akpm@linux-foundation.org> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 22 Oct 2008 15:16:33 -0400 (EDT) Steven Rostedt wrote: > > Also, I hope that the above code is called from within a > > pagefault_disable()d region? Or are relying upon some magical > > side-effect of something which happens to do the same thing as > > pagefault_disable()? IOW: by what means does the above code ensure > > that do_page_fault() will see in_atomic()==true? > > This code is called from kstop_machine, or simply has interrupts disabled. in_atomic() doesn't test irqs_disabled()! Still, probe_kernel_write() correctly handles the secret-argument-passing to do_page_fault().