From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: Kernel oops with 2.6.26, padlock and ipsec: probably problem with fpu state changes Date: Sat, 09 Aug 2008 09:05:50 -0700 Message-ID: <489DC05E.2080901@zytor.com> References: <200807171653.59177.wolfgang.walter@stwm.de> <20080806201401.GA607@linux-os.sc.intel.com> <200808071823.02364.wolfgang.walter@stwm.de> <200808081236.55172.wolfgang.walter@stwm.de> <20080808185356.GC607@linux-os.sc.intel.com> <489C97FB.2030408@zytor.com> <20080808231121.GA13158@linux-os.sc.intel.com> <20080809143727.GA30499@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Suresh Siddha , Wolfgang Walter , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Ingo Molnar , "viro@ZenIV.linux.org.uk" , "vegard.nossum@gmail.com" To: Herbert Xu Return-path: Received: from terminus.zytor.com ([198.137.202.10]:37695 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750758AbYHIQMd (ORCPT ); Sat, 9 Aug 2008 12:12:33 -0400 In-Reply-To: <20080809143727.GA30499@gondor.apana.org.au> Sender: netdev-owner@vger.kernel.org List-ID: Herbert Xu wrote: > On Fri, Aug 08, 2008 at 04:11:21PM -0700, Suresh Siddha wrote: >> With out the recent dynamic fpu allocation changes, while we don't see oops, >> there is a possible race still present in older kernels(for example, >> while kernel is using kernel_fpu_begin() in some optimized clear/copy >> page and an interrupt/softirq happens which uses these padlock >> instructions generating DNA fault). > > No this wasn't a problem because kernel_fpu_begin clears TS and > therefore we don't get faults on SSE instructions. > > However, with your patch it will become a problem due to the > fact that it wasn't designed to be nested. > We're invoking this code from interrupt handlers? -hpa