From mboxrd@z Thu Jan 1 00:00:00 1970 From: Florian Weimer Subject: Re: [PATCH v5 07/27] mm/mmap: Create a guard area between VMAs Date: Fri, 12 Oct 2018 12:24:25 +0200 Message-ID: <87va67799i.fsf@mid.deneb.enyo.de> References: <20181011151523.27101-1-yu-cheng.yu@intel.com> <20181011151523.27101-8-yu-cheng.yu@intel.com> <20167c74-9b98-6fa1-972e-bcd2c9c4a1c8@linux.intel.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: In-Reply-To: <20167c74-9b98-6fa1-972e-bcd2c9c4a1c8@linux.intel.com> (Dave Hansen's message of "Thu, 11 Oct 2018 13:49:09 -0700") Sender: linux-kernel-owner@vger.kernel.org To: Dave Hansen Cc: Yu-cheng Yu , x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Cyrill Gorcunov , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel List-Id: linux-arch.vger.kernel.org * Dave Hansen: > On 10/11/2018 08:15 AM, Yu-cheng Yu wrote: >> Create a guard area between VMAs to detect memory corruption. > > This is a pretty major change that has a bunch of end-user implications. > It's not dependent on any debugging options and can't be turned on/off > by individual apps, at runtime, or even at boot. > > Its connection to this series is also tenuous and not spelled out in the > exceptionally terse changelog. I agree. We did have application failures due to the introduction of the stack gap, so this change is likely to cause failures when applied to existing mappings as well. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from albireo.enyo.de ([5.158.152.32]:51670 "EHLO albireo.enyo.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726917AbeJLR4d (ORCPT ); Fri, 12 Oct 2018 13:56:33 -0400 From: Florian Weimer Subject: Re: [PATCH v5 07/27] mm/mmap: Create a guard area between VMAs References: <20181011151523.27101-1-yu-cheng.yu@intel.com> <20181011151523.27101-8-yu-cheng.yu@intel.com> <20167c74-9b98-6fa1-972e-bcd2c9c4a1c8@linux.intel.com> Date: Fri, 12 Oct 2018 12:24:25 +0200 In-Reply-To: <20167c74-9b98-6fa1-972e-bcd2c9c4a1c8@linux.intel.com> (Dave Hansen's message of "Thu, 11 Oct 2018 13:49:09 -0700") Message-ID: <87va67799i.fsf@mid.deneb.enyo.de> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-arch-owner@vger.kernel.org List-ID: To: Dave Hansen Cc: Yu-cheng Yu , x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Cyrill Gorcunov , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Pavel Machek , Peter Zijlstra , Randy Dunlap , "Ravi V. Shankar" , Vedvyas Shanbhogue Message-ID: <20181012102425.q5pE4vQBKK1R8s3-ESfsa4EskwCL99xA3vG0fUcRWVc@z> * Dave Hansen: > On 10/11/2018 08:15 AM, Yu-cheng Yu wrote: >> Create a guard area between VMAs to detect memory corruption. > > This is a pretty major change that has a bunch of end-user implications. > It's not dependent on any debugging options and can't be turned on/off > by individual apps, at runtime, or even at boot. > > Its connection to this series is also tenuous and not spelled out in the > exceptionally terse changelog. I agree. We did have application failures due to the introduction of the stack gap, so this change is likely to cause failures when applied to existing mappings as well.