Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1765802AbXHWVux (ORCPT ); Thu, 23 Aug 2007 17:50:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1761493AbXHWVup (ORCPT ); Thu, 23 Aug 2007 17:50:45 -0400 Received: from smtp2.linux-foundation.org ([207.189.120.14]:51356 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760979AbXHWVuo (ORCPT ); Thu, 23 Aug 2007 17:50:44 -0400 Date: Thu, 23 Aug 2007 14:50:38 -0700 From: Andrew Morton To: Frederik Deweerdt Cc: linux-kernel@vger.kernel.org, jeremy@goop.org Subject: Re: [-mm patch] enforce noreplace-smp in alternative_instructions() Message-Id: <20070823145038.9895784f.akpm@linux-foundation.org> In-Reply-To: <20070822202551.GB31846@slug> References: <20070822020648.5ea3a612.akpm@linux-foundation.org> <20070822202551.GB31846@slug> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.6; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1950 Lines: 57 On Wed, 22 Aug 2007 22:25:51 +0200 Frederik Deweerdt wrote: > On Wed, Aug 22, 2007 at 02:06:48AM -0700, Andrew Morton wrote: > > > > ftp://ftp.kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.23-rc3/2.6.23-rc3-mm1/ > > > Hi Jeremy, > > arch/i386/kernel/alternative.c:alternative_instructions() doesn't > check for noreplace-smp before setting capability bits and freeing the > __smp_locks section. umm, so? What happens then? What bug is being fixed here, and what are its consequences? > Every call to alternatives_smp_unlock() checks for noreplace-smp > beforehand, so remove the check from there. > > Boot tested on i386 with UP+noreplace-smp (lguest) and SMP (real hardware) > > Regards, > Frederik > > Signed-off-by: Frederik Deweerdt > > diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c > index 9f4ac8b..7c5af80 100644 > --- a/arch/i386/kernel/alternative.c > +++ b/arch/i386/kernel/alternative.c > @@ -221,9 +221,6 @@ static void alternatives_smp_unlock(u8 **start, u8 **end, u8 *text, u8 *text_end > u8 **ptr; > char insn[1]; > > - if (noreplace_smp) > - return; > - > add_nops(insn, 1); > for (ptr = start; ptr < end; ptr++) { > if (*ptr < text) > @@ -406,7 +403,7 @@ void __init alternative_instructions(void) > #endif > > #ifdef CONFIG_SMP > - if (smp_alt_once) { > + if (smp_alt_once && !noreplace_smp) { > if (1 == num_possible_cpus()) { > printk(KERN_INFO "SMP alternatives: switching to UP code\n"); > set_bit(X86_FEATURE_UP, boot_cpu_data.x86_capability); You refer to rc3-mm1 and this is described as a "-mm patch" but it seems to also be applicable to mainline? - 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/