From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752196AbdLJSvJ (ORCPT ); Sun, 10 Dec 2017 13:51:09 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:51450 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751991AbdLJSvH (ORCPT ); Sun, 10 Dec 2017 13:51:07 -0500 Date: Sun, 10 Dec 2017 10:51:01 -0800 From: "Paul E. McKenney" To: Andy Shevchenko Cc: Kees Cook , Linus Torvalds , David Laight , "linux-kernel@vger.kernel.org" , "mingo@kernel.org" , "jiangshanlai@gmail.com" , "dipankar@in.ibm.com" , "akpm@linux-foundation.org" , "mathieu.desnoyers@efficios.com" , "josh@joshtriplett.org" , "tglx@linutronix.de" , "peterz@infradead.org" , "rostedt@goodmis.org" , "dhowells@redhat.com" , "edumazet@google.com" , "fweisbec@gmail.com" , "oleg@redhat.com" Subject: Re: [PATCH tip/core/rcu 02/20] torture: Prepare scripting for shift from %p to %pK Reply-To: paulmck@linux.vnet.ibm.com References: <20171201200819.GA25519@linux.vnet.ibm.com> <1512158945-27269-2-git-send-email-paulmck@linux.vnet.ibm.com> <20171204134203.GR7829@linux.vnet.ibm.com> <20171204161100.GT7829@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 17121018-0008-0000-0000-000002AD5825 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00008185; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000244; SDB=6.00958289; UDB=6.00484536; IPR=6.00738311; BA=6.00005733; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00018463; XFM=3.00000015; UTC=2017-12-10 18:51:03 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17121018-0009-0000-0000-0000378DBC2C Message-Id: <20171210185101.GI7829@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-12-10_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1711220000 definitions=main-1712100283 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Dec 10, 2017 at 02:52:49PM +0200, Andy Shevchenko wrote: > On Mon, Dec 4, 2017 at 6:11 PM, Paul E. McKenney > wrote: > > On Mon, Dec 04, 2017 at 02:13:38PM +0000, David Laight wrote: > >> From: Paul E. McKenney > >> > Sent: 04 December 2017 13:42 > >> > On Mon, Dec 04, 2017 at 12:32:30PM +0000, David Laight wrote: > >> > > From: Paul E. McKenney > >> > > > Sent: 01 December 2017 20:09 > >> > > > > >> > > > Because %p prints "(null)" and %pK prints "0000000000000000" or (on > >> > > > 32-bit systems) "00000000", this commit adjusts torture-test scripting > >> > > > accordingly. > >> > > > >> > > Surely NULL v not-NULL is one bit of info that the message needs to contain? > >> > > >> > Indeed. So the script needs to check for the strings "00000000", > >> > "0000000000000000", and "(null) in the console output". The "(null)" > >> > is what "%p" prints for a NULL pointer, and the other two strings are > >> > what "%pK" prints for a NULL pointer. > >> > > >> > Or am I missing your point? > >> > >> I was thinking that even %pK should print "(null)". > > > > That was my expectation, as in the need for this patch came as a > > surprise to me. > > > >> Perhaps it should have printed a fixed, non-zero value for non-zero > >> pointers. > > > > I must leave this to the people who have a dog in that contest. ;-) > > Since there is an ongoing discussion with security people near to %pK > and alike, I added Kees and Linus to Cc list. > > The proposed change can be done easily, though I have no knowledge > about possible implications. One question I have is whether the patches to convert RCU to %pK are even desirable at this point: https://lwn.net/Articles/737451/ If something like the patches in that article get to mainline, then shouldn't I just drop RCU's %pK patches? Thanx, Paul