From patchwork Wed Aug 22 10:03:48 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Avi Kivity X-Patchwork-Id: 1360821 Return-Path: X-Original-To: patchwork-kvm@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id CCE1DDF280 for ; Wed, 22 Aug 2012 10:04:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752167Ab2HVKEQ (ORCPT ); Wed, 22 Aug 2012 06:04:16 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46572 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751502Ab2HVKEO (ORCPT ); Wed, 22 Aug 2012 06:04:14 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q7MA3sPG004795 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Wed, 22 Aug 2012 06:03:55 -0400 Received: from balrog.usersys.tlv.redhat.com (dhcp-4-121.tlv.redhat.com [10.35.4.121]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id q7MA3mvZ005717; Wed, 22 Aug 2012 06:03:49 -0400 Message-ID: <5034AE84.90708@redhat.com> Date: Wed, 22 Aug 2012 13:03:48 +0300 From: Avi Kivity User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120717 Thunderbird/14.0 MIME-Version: 1.0 To: Tomas Racek , the arch/x86 maintainers CC: Michael Tokarev , Borislav Petkov , kvm-devel , Marcelo Tosatti , qemu-devel@nongnu.org, linux-kernel@vger.kernel.org, Anthony Liguori , "H. Peter Anvin" , Alan Cox , Alan Cox , linux-kernel Subject: [PATCH] x86, alternative: fix p6 nops on non-modular kernels References: <592618508.2357204.1345541334852.JavaMail.root@redhat.com> <5034AC61.9030704@redhat.com> In-Reply-To: <5034AC61.9030704@redhat.com> X-Scanned-By: MIMEDefang 2.67 on 10.5.11.11 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 08/22/2012 12:54 PM, Avi Kivity wrote: > On 08/21/2012 12:28 PM, Tomas Racek wrote: >> >> http://fi.muni.cz/~xracek/debian2.img.bz2 >> >> Other things are the same. >> >> The runtest.sh sets environment for xfstests and runs test 285 which I wrote and and which should test if FS sends discard requests only on free sectors: >> 285: >> 1. Create loop device and FS on it. >> 2. Populate it with some garbage. >> 3. Get free sectors from FS. >> 4. Run fstrim and look for discard requests via blk tracer. >> 5. Compare free sectors to discard requests. >> >> The test itself can have some issues but I'm pretty sure it shouldn't crash the system. ;-) > > Does the following patch help? > It's obvious that it should. You're running a non-modular kernel, and those nops are discarded (probably a leftover from the days patching was a boot-only activity), so the kernel patched garbage over its own code. -------8<----cut-here-----8<----------------------------------- From: Avi Kivity Date: Wed, 22 Aug 2012 12:58:18 +0300 Subject: [PATCH] x86, alternative: fix p6 nops on non-modular kernels Probably a leftover from the early days of self-patching, p6nops are marked __initconst_or_module, which causes them to be discarded in a non-modular kernel. If something later triggers patching, it will overwrite kernel code with garbage. Reported-by: Tomas Racek Signed-off-by: Avi Kivity diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c index afb7ff7..ced4534 100644 --- a/arch/x86/kernel/alternative.c +++ b/arch/x86/kernel/alternative.c @@ -165,7 +165,7 @@ static int __init setup_noreplace_paravirt(char *str) #endif #ifdef P6_NOP1 -static const unsigned char __initconst_or_module p6nops[] = +static const unsigned char p6nops[] = { P6_NOP1, P6_NOP2,