From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934113AbcAZIkG (ORCPT ); Tue, 26 Jan 2016 03:40:06 -0500 Received: from mail.karo-electronics.de ([81.173.242.67]:52925 "EHLO mail.karo-electronics.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932681AbcAZIkC convert rfc822-to-8bit (ORCPT ); Tue, 26 Jan 2016 03:40:02 -0500 Date: Tue, 26 Jan 2016 09:39:51 +0100 From: Lothar =?UTF-8?B?V2HDn21hbm4=?= To: Brian Norris Cc: Rusty Russell , linux-kernel@vger.kernel.org Subject: Re: module: Fix regression introduced by commit: b0d7290e85a5 "module: clean up RO/NX handling." Message-ID: <20160126093951.1d6c80fe@ipc1.ka-ro> In-Reply-To: <20160125234108.GA16175@google.com> References: <1453720311-9594-1-git-send-email-LW@KARO-electronics.de> <20160125234108.GA16175@google.com> Organization: Ka-Ro electronics GmbH MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Mon, 25 Jan 2016 15:41:08 -0800 Brian Norris wrote: > On Mon, Jan 25, 2016 at 12:11:51PM +0100, Lothar Wassmann wrote: > > commit b0d7290e85a5 ("module: clean up RO/NX handling.") > > threw away the size checks which were in place before calling the > > set_memory_*() functions. > > This produces a kernel bug upon module load with > > CONFIG_DEBUG_SET_MODULE_RONX=y: > > > > kernel BUG at mm/memory.c:1898! > > Internal error: Oops - BUG: 0 [#1] ARM > > Modules linked in: > > CPU: 0 PID: 825 Comm: modprobe Not tainted 4.4.0-next-20160121+ #53 > > Hardware name: Freescale MXS (Device Tree) > > task: cef6c380 ti: ce93a000 task.ti: ce93a000 > > PC is at apply_to_page_range+0x190/0x1bc > > LR is at change_memory_common+0x74/0xcc > > pc : [] lr : [] psr: 60000013 > > sp : ce93be40 ip : bf011000 fp : bf012000 > > r10: bf012000 r9 : bf0091d4 r8 : ce93be80 > > r7 : 00000000 r6 : bf012000 r5 : 00000001 r4 : bf012000 > > r3 : c0011d38 r2 : 00000000 r1 : bf012000 r0 : c0633458 > > Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA ARM Segment none > > Control: 0005317f Table: 4ef0c000 DAC: 00000051 > > Process modprobe (pid: 825, stack limit = 0xce93a190) > > Stack: (0xce93be40 to 0xce93c000) > > be40: c0633458 bf012000 00000000 bf012000 00000001 bf012000 00000000 00000080 > > be60: bf0091d4 ce93bef4 00000000 c0011ce0 ce93be80 00000000 bf0071dc bf0091e4 > > be80: 00000080 00000000 bf009100 ce93bf48 00000001 bf00910c bf009100 00000000 > > bea0: bf0091d4 c005d2a0 00000000 cfbd8de0 00000000 00000014 007fb980 00000000 > > bec0: d0a1d01c bf009250 bf00910c 00000000 d0a19000 b6e4b000 00000f80 755f6f74 > > bee0: 5f726573 bf007024 00000032 bf0071b4 00000006 00000000 00000000 00000000 > > bf00: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 > > bf20: c005da70 0000306c 00000000 b6e4f06c d0a1d06c ce93a000 007fb980 00000051 > > bf40: 007fbbd8 c005dae0 d0a0a000 0001306c d0a1c98c d0a13c07 d0a177c8 0000a000 > > bf60: 0000cbe0 00000000 00000000 00000000 0000002a 0000002b 00000020 00000024 > > bf80: 00000018 00000000 b6f83228 bec859f8 00000000 00000080 c000a4e4 ce93a000 > > bfa0: 00000000 c000a340 b6f83228 bec859f8 b6e3c000 0001306c 007fb980 00000000 > > bfc0: b6f83228 bec859f8 00000000 00000080 007fb980 00000008 00000000 007fbbd8 > > bfe0: b6f1fa70 bec856c8 0000aab4 b6f1fa80 60000010 b6e3c000 00000000 00000000 > > [] (apply_to_page_range) from [] (change_memory_common+0x74/0xcc) > > [] (change_memory_common) from [] (load_module+0x16c8/0x1e3c) > > [] (load_module) from [] (SyS_init_module+0xcc/0x138) > > [] (SyS_init_module) from [] (ret_fast_syscall+0x0/0x38) > > Code: e0834104 eaffffc3 e5191008 eaffffbb (e7f001f2) > > ---[ end trace fbf287e335e94b28 ]--- > > > > This happens because the set_memory_*() functions are eventually being > > called with a zero parameter and thus apply_to_page_range() in > > mm/memory.c barfs due to: > > unsigned long end = addr + size; > > ... > > BUG_ON(addr >= end); > > Hit this BUG_ON() on a mt8173 platform with v4.5-rc1. > I just found a patch that fixes this problem in a different way (making the set_memory_*() functions accept a zero size argument): <1453561543-14756-1-git-send-email-mika.penttila@nextfour.com> http://lkml.iu.edu/hypermail/linux/kernel/1601.2/04934.html So this patch is obsolete. Lothar Waßmann