From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755926Ab3EVKQ7 (ORCPT ); Wed, 22 May 2013 06:16:59 -0400 Received: from merlin.infradead.org ([205.233.59.134]:39094 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755745Ab3EVKQy (ORCPT ); Wed, 22 May 2013 06:16:54 -0400 Date: Wed, 22 May 2013 12:16:10 +0200 From: Peter Zijlstra To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, Catalin Marinas , Will Deacon , David Howells , Hirokazu Takata , Michal Simek , Koichi Yasutake , Benjamin Herrenschmidt , Paul Mackerras , Chris Metcalf , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Arnd Bergmann , linux-arm-kernel@lists.infradead.org, linux-m32r@ml.linux-m32r.org, linux-m32r-ja@ml.linux-m32r.org, microblaze-uclinux@itee.uq.edu.au, linux-am33-list@redhat.com, linuxppc-dev@lists.ozlabs.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org, rostedt@goodmis.org Subject: Re: [PATCH v2 10/10] kernel: might_fault does not imply might_sleep Message-ID: <20130522101610.GL18810@twins.programming.kicks-ass.net> References: <1f85dc8e6a0149677563a2dfb4cef9a9c7eaa391.1368702323.git.mst@redhat.com> <20130516184041.GP19669@dyad.programming.kicks-ass.net> <20130519093526.GD19883@redhat.com> <20130521115734.GA9554@twins.programming.kicks-ass.net> <20130522094709.GA26451@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130522094709.GA26451@redhat.com> User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 22, 2013 at 12:47:09PM +0300, Michael S. Tsirkin wrote: > > > > +static inline bool __can_fault(void) > > +{ > > + /* > > + * Some code (nfs/sunrpc) uses socket ops on kernel memory while > > + * holding the mmap_sem, this is safe because kernel memory doesn't > > + * get paged out, therefore we'll never actually fault, and the > > + * below annotations will generate false positives. > > + */ > > + if (segment_eq(get_fs(), KERNEL_DS)) > > + return false; > > + > > + if (in_atomic() /* || pagefault_disabled() */) > > One question here: I'm guessing you put this comment here > for illustrative purposes, implying code that will > be enabled in -rt? > We don't want it upstream I think, right? Right, and as a reminder that when we do this we need to add a patch to -rt. But yeah, we should have a look and see if its worth pulling those patches from -rt into mainline in some way shape or form. They're big but trivial IIRC. I'm fine with you leaving that comment out though.. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Zijlstra Subject: Re: [PATCH v2 10/10] kernel: might_fault does not imply might_sleep Date: Wed, 22 May 2013 12:16:10 +0200 Message-ID: <20130522101610.GL18810@twins.programming.kicks-ass.net> References: <1f85dc8e6a0149677563a2dfb4cef9a9c7eaa391.1368702323.git.mst@redhat.com> <20130516184041.GP19669@dyad.programming.kicks-ass.net> <20130519093526.GD19883@redhat.com> <20130521115734.GA9554@twins.programming.kicks-ass.net> <20130522094709.GA26451@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20130522094709.GA26451@redhat.com> Sender: owner-linux-mm@kvack.org To: "Michael S. Tsirkin" Cc: linux-kernel@vger.kernel.org, Catalin Marinas , Will Deacon , David Howells , Hirokazu Takata , Michal Simek , Koichi Yasutake , Benjamin Herrenschmidt , Paul Mackerras , Chris Metcalf , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Arnd Bergmann , linux-arm-kernel@lists.infradead.org, linux-m32r@ml.linux-m32r.org, linux-m32r-ja@ml.linux-m32r.org, microblaze-uclinux@itee.uq.edu.au, linux-am33-list@redhat.com, linuxppc-dev@lists.ozlabs.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, kvm@vger.kernel.org, rostedt@goodmis.org List-Id: linux-arch.vger.kernel.org On Wed, May 22, 2013 at 12:47:09PM +0300, Michael S. Tsirkin wrote: > > > > +static inline bool __can_fault(void) > > +{ > > + /* > > + * Some code (nfs/sunrpc) uses socket ops on kernel memory while > > + * holding the mmap_sem, this is safe because kernel memory doesn't > > + * get paged out, therefore we'll never actually fault, and the > > + * below annotations will generate false positives. > > + */ > > + if (segment_eq(get_fs(), KERNEL_DS)) > > + return false; > > + > > + if (in_atomic() /* || pagefault_disabled() */) > > One question here: I'm guessing you put this comment here > for illustrative purposes, implying code that will > be enabled in -rt? > We don't want it upstream I think, right? Right, and as a reminder that when we do this we need to add a patch to -rt. But yeah, we should have a look and see if its worth pulling those patches from -rt into mainline in some way shape or form. They're big but trivial IIRC. I'm fine with you leaving that comment out though.. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:4978:20e::2]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id AD0B82C00A7 for ; Wed, 22 May 2013 20:16:49 +1000 (EST) Date: Wed, 22 May 2013 12:16:10 +0200 From: Peter Zijlstra To: "Michael S. Tsirkin" Subject: Re: [PATCH v2 10/10] kernel: might_fault does not imply might_sleep Message-ID: <20130522101610.GL18810@twins.programming.kicks-ass.net> References: <1f85dc8e6a0149677563a2dfb4cef9a9c7eaa391.1368702323.git.mst@redhat.com> <20130516184041.GP19669@dyad.programming.kicks-ass.net> <20130519093526.GD19883@redhat.com> <20130521115734.GA9554@twins.programming.kicks-ass.net> <20130522094709.GA26451@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20130522094709.GA26451@redhat.com> Cc: linux-m32r-ja@ml.linux-m32r.org, kvm@vger.kernel.org, Catalin Marinas , Will Deacon , David Howells , linux-mm@kvack.org, Paul Mackerras , "H. Peter Anvin" , linux-arch@vger.kernel.org, linux-am33-list@redhat.com, Hirokazu Takata , x86@kernel.org, Ingo Molnar , Arnd Bergmann , microblaze-uclinux@itee.uq.edu.au, Chris Metcalf , rostedt@goodmis.org, Thomas Gleixner , linux-arm-kernel@lists.infradead.org, Michal Simek , linux-m32r@ml.linux-m32r.org, linux-kernel@vger.kernel.org, Koichi Yasutake , linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, May 22, 2013 at 12:47:09PM +0300, Michael S. Tsirkin wrote: > > > > +static inline bool __can_fault(void) > > +{ > > + /* > > + * Some code (nfs/sunrpc) uses socket ops on kernel memory while > > + * holding the mmap_sem, this is safe because kernel memory doesn't > > + * get paged out, therefore we'll never actually fault, and the > > + * below annotations will generate false positives. > > + */ > > + if (segment_eq(get_fs(), KERNEL_DS)) > > + return false; > > + > > + if (in_atomic() /* || pagefault_disabled() */) > > One question here: I'm guessing you put this comment here > for illustrative purposes, implying code that will > be enabled in -rt? > We don't want it upstream I think, right? Right, and as a reminder that when we do this we need to add a patch to -rt. But yeah, we should have a look and see if its worth pulling those patches from -rt into mainline in some way shape or form. They're big but trivial IIRC. I'm fine with you leaving that comment out though.. From mboxrd@z Thu Jan 1 00:00:00 1970 From: peterz@infradead.org (Peter Zijlstra) Date: Wed, 22 May 2013 12:16:10 +0200 Subject: [PATCH v2 10/10] kernel: might_fault does not imply might_sleep In-Reply-To: <20130522094709.GA26451@redhat.com> References: <1f85dc8e6a0149677563a2dfb4cef9a9c7eaa391.1368702323.git.mst@redhat.com> <20130516184041.GP19669@dyad.programming.kicks-ass.net> <20130519093526.GD19883@redhat.com> <20130521115734.GA9554@twins.programming.kicks-ass.net> <20130522094709.GA26451@redhat.com> Message-ID: <20130522101610.GL18810@twins.programming.kicks-ass.net> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, May 22, 2013 at 12:47:09PM +0300, Michael S. Tsirkin wrote: > > > > +static inline bool __can_fault(void) > > +{ > > + /* > > + * Some code (nfs/sunrpc) uses socket ops on kernel memory while > > + * holding the mmap_sem, this is safe because kernel memory doesn't > > + * get paged out, therefore we'll never actually fault, and the > > + * below annotations will generate false positives. > > + */ > > + if (segment_eq(get_fs(), KERNEL_DS)) > > + return false; > > + > > + if (in_atomic() /* || pagefault_disabled() */) > > One question here: I'm guessing you put this comment here > for illustrative purposes, implying code that will > be enabled in -rt? > We don't want it upstream I think, right? Right, and as a reminder that when we do this we need to add a patch to -rt. But yeah, we should have a look and see if its worth pulling those patches from -rt into mainline in some way shape or form. They're big but trivial IIRC. I'm fine with you leaving that comment out though..