From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762141AbbA3Mrn (ORCPT ); Fri, 30 Jan 2015 07:47:43 -0500 Received: from eddie.linux-mips.org ([148.251.95.138]:52017 "EHLO cvs.linux-mips.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754800AbbA3Mrl (ORCPT ); Fri, 30 Jan 2015 07:47:41 -0500 Date: Fri, 30 Jan 2015 12:47:39 +0000 (GMT) From: "Maciej W. Rozycki" To: James Hogan cc: Aaro Koskinen , Ralf Baechle , David Daney , linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, Hemmo Nieminen , stable@vger.kernel.org Subject: Re: [PATCH v2 2/2] MIPS: fix kernel lockup or crash after CPU offline/online In-Reply-To: <54CB5B59.5050203@imgtec.com> Message-ID: References: <1421355719-17576-1-git-send-email-aaro.koskinen@iki.fi> <1421355719-17576-2-git-send-email-aaro.koskinen@iki.fi> <54CB5B59.5050203@imgtec.com> User-Agent: Alpine 2.11 (LFD 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 30 Jan 2015, James Hogan wrote: > > Hmm, why can a call to `printk' cause a TLB miss, what's so special about > > this function? Does it use kernel mapped addresses for any purpose such > > as `vmalloc'? > > It would be the fact netconsole (or whatever other console is in use) is > built as a kernel module, memory for which is allocated from the vmalloc > area. Ah, I see, thanks for enlightening me. But in that case wouldn't it be possible to postpone console output from `printk' until it is safe to access the device? In a manner similar to how for example we handle calls to `printk' made from the hardirq context. That would make things less fragile. Maciej