Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752888Ab2BTLBH (ORCPT ); Mon, 20 Feb 2012 06:01:07 -0500 Received: from merlin.infradead.org ([205.233.59.134]:43679 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752007Ab2BTLBF convert rfc822-to-8bit (ORCPT ); Mon, 20 Feb 2012 06:01:05 -0500 Message-ID: <1329735648.2293.307.camel@twins> Subject: Re: [PATCH 0/2 x86] fix some page faults in nmi if kmemcheck is enabled From: Peter Zijlstra To: Li Zhong Cc: LKML , tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, paulus@samba.org, mingo@elte.hu, acme@ghostprotocols.net Date: Mon, 20 Feb 2012 12:00:48 +0100 In-Reply-To: <1329717665.3448.28.camel@ThinkPad-T61> References: <1329717665.3448.28.camel@ThinkPad-T61> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7BIT X-Mailer: Evolution 3.2.2- Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3062 Lines: 55 On Mon, 2012-02-20 at 14:01 +0800, Li Zhong wrote: > If CONFIG_KMEMCHECK is enabled, there might be page faults in nmi if the > pages are marked as not present by kmemcheck, like following: > > [ 4.535803] WARNING: at arch/x86/mm/kmemcheck/kmemcheck.c:634 kmemcheck_fault+0xb9/0xd0() > [ 4.633429] Hardware name: System x3650 M3 -[7945AC1]- > [ 4.694710] Modules linked in: > [ 4.731105] Pid: 1, comm: swapper/0 Not tainted 3.3.0-rc3 #15 > [ 4.799654] Call Trace: > [ 4.828751] [] warn_slowpath_common+0x7a/0xb0 > [ 4.907713] [] warn_slowpath_null+0x15/0x20 > [ 4.977301] [] kmemcheck_fault+0xb9/0xd0 > [ 5.043778] [] do_page_fault+0x406/0x550 > [ 5.110252] [] page_fault+0x25/0x30 > [ 5.171535] [] ? nmi_handle.clone.1+0x75/0xc0 > [ 5.243202] [] ? nmi_handle.clone.1+0x3f/0xc0 > [ 5.314867] [] ? __die+0xf0/0xf0 > [ 5.373038] [] do_nmi+0x10f/0x360 > [ 5.432243] [] restart_nmi+0x1a/0x1e > [ 5.494565] [] ? general_protection+0x30/0x30 > [ 5.566234] [] ? general_protection+0x30/0x30 > [ 5.637898] [] ? general_protection+0x30/0x30 > [ 5.709566] <> [] ? rb_insert_color+0xa4/0x150 > [ 5.788526] [] sysfs_link_sibling+0x8b/0x110 > [ 5.859155] [] __sysfs_add_one+0xc1/0x100 > [ 5.926666] [] sysfs_add_one+0x26/0xd0 > [ 5.991065] [] sysfs_add_file_mode+0xc4/0x100 > [ 6.062731] [] internal_create_group+0xc1/0x1a0 > [ 6.136473] [] sysfs_create_group+0xe/0x10 > [ 6.205026] [] dpm_sysfs_add+0x2a/0xd0 > [ 6.269425] [] device_add+0x5e5/0x730 > [ 6.332783] [] device_register+0x19/0x20 > [ 6.399260] [] add_memory_section+0x158/0x1e0 > [ 6.470927] [] memory_dev_init+0x75/0x108 > [ 6.538439] [] driver_init+0x31/0x33 > [ 6.600762] [] kernel_init+0xcc/0x169 > [ 6.664121] [] kernel_thread_helper+0x4/0x10 > [ 6.734749] [] ? start_kernel+0x3ab/0x3ab > [ 6.802261] [] ? gs_change+0x13/0x13 > [ 6.864585] ---[ end trace a7919e7f17c0a725 ]--- > > These two patches tries to fix some of the problems by avoiding using the > non-present pages. Hell no, these are some of the ugliest patches I've seen in a while. Not to mention that their changelogs are utter crap since they don't even explain why they're doing what they're doing. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/