From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752959AbbCJSqF (ORCPT ); Tue, 10 Mar 2015 14:46:05 -0400 Received: from mail-qg0-f45.google.com ([209.85.192.45]:34934 "EHLO mail-qg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751330AbbCJSqC (ORCPT ); Tue, 10 Mar 2015 14:46:02 -0400 Message-ID: <54FF3BE3.308@hurleysoftware.com> Date: Tue, 10 Mar 2015 14:45:55 -0400 From: Peter Hurley User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-Version: 1.0 To: Stas Sergeev , Andrew Morton CC: Linux kernel , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH] n_tty: use kmalloc() instead of vmalloc() to avoid crash on armada-xp References: <54FF21BE.2040506@list.ru> <54FF2B45.8060407@hurleysoftware.com> <54FF2F3E.7050503@list.ru> In-Reply-To: <54FF2F3E.7050503@list.ru> 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 On 03/10/2015 01:51 PM, Stas Sergeev wrote: > 10.03.2015 20:35, Peter Hurley пишет: >> On 03/10/2015 12:54 PM, Stas Sergeev wrote: >>> Hello, the patch below is needed for a successful boot on armada-xp. >>> >>> >>> -=-=-=-=-=-=-=-=-=# Don't remove this line #=-=-=-=-=-=-=-=-=- >>> This fixes the following crash at boot: >>> >>> Unhandled fault: external abort on non-linefetch (0x808) at 0xf00ca018 >>> Internal error: : 808 [#1] SMP ARM >>> >>> CPU: 2 PID: 1 Comm: swapper/0 Not tainted 4.0.0-rc1 #3 >>> Hardware name: Marvell Armada 370/XP (Device Tree) >>> task: ed41e800 ti: ed43e000 task.ti: ed43e000 >>> PC is at _set_bit+0x28/0x50 >>> LR is at n_tty_set_termios+0x328/0x358 >>> pc : [] lr : [] psr: 40000113 >>> sp : ed43fd00 ip : 00000000 fp : 00000000 >>> r10: 00000002 r9 : 00000000 r8 : ec930200 >>> r7 : 00000000 r6 : f00ca018 r5 : f00ca000 r4 : ed69cc00 >>> r3 : 00002000 r2 : 00002000 r1 : f00ca018 r0 : 00000000 >>> Flags: nZcv IRQs on FIQs on Mode SVC_32 ISA ARM Segment kernel >>> Control: 10c5387d Table: 0000406a DAC: 00000015 >>> Process swapper/0 (pid: 1, stack limit = 0xed43e220) >>> >>> The offending instruction in _set_bit() is "strex r0, r2, [r1]" >>> For some reason the exclusive access instructions do not like the >>> vmalloc() space... While there may be another fix to make them >>> fine about vmalloc() space, it still looks like a good idea to >>> use kmalloc() for allocating a small (sub-page) struct. >> NAK. >> >> struct n_tty_data is order 2, not sub-page. > OK, you are right, sorry. 8844 bytes. > Is this really a target for vmalloc() though? I thought kmalloc() > is preferable even for that size. It doubles as a selftest for arch page table setup :) I considered only using vmalloc() as a fallback, but problems like this make me *less* interested in doing that. At least this way the problem is unambiguous. Regards, Peter Hurley