From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christian Borntraeger Subject: Re: [PATCH for stable] x86/spinlocks/paravirt: Fix memory corruption on unlock Date: Wed, 25 Feb 2015 11:14:38 +0100 Message-ID: <54EDA08E.5080901@de.ibm.com> References: <1424769899-14158-1-git-send-email-raghavendra.kt@linux.vnet.ibm.com> <20150224141731.GA16033@kroah.com> <20150224144737.GA26074@gmail.com> <54ECC0A1.1080802@linux.vnet.ibm.com> <20150224183844.GA8654@kroah.com> <20150225100806.GA7134@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Cc: Raghavendra K T , tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, torvalds@linux-foundation.org, konrad.wilk@oracle.com, pbonzini@redhat.com, peterz@infradead.org, paulmck@linux.vnet.ibm.com, waiman.long@hp.com, davej@redhat.com, oleg@redhat.com, x86@kernel.org, jeremy@goop.org, paul.gortmaker@windriver.com, ak@linux.intel.com, jasowang@redhat.com, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, riel@redhat.com, akpm@linux-foundation.org, a.ryabinin@samsung.com, sasha.levin@oracle.com, dave@stgolabs.net, stable@vger.kernel.org To: Ingo Molnar , Greg KH Return-path: In-Reply-To: <20150225100806.GA7134@gmail.com> Sender: stable-owner@vger.kernel.org List-Id: kvm.vger.kernel.org Am 25.02.2015 um 11:08 schrieb Ingo Molnar: > > * Greg KH wrote: > >>>> It's: >>>> >>>> d6abfdb20223 x86/spinlocks/paravirt: Fix memory corruption on unlock >>> >>> Yes, This is the original patch. Please note I have taken out the >>> READ_ONCE changes from the original patch to avoid build warnings >>> mentioned below. >>> (Those READ_ONCE changes were cosmetic and was not present in the >>> previous versions) >>> >>>> >>>> You'll also need this fix from Linus to avoid (harmless) >>>> build warnings: >>>> >>>> dd36929720f4 kernel: make READ_ONCE() valid on const arguments >>> >>> So this may not be absolutely necessary with the current patch. >> >> I'd prefer to be as close as possible to the upstream >> patch. So if applying both of these patches will work, >> I'd much rather do that. Changing patches when >> backporting them to stable for no good reason than to >> clean things up, just confuses everyone involved. >> >> Let's keep our messy history :) > > By all means! > > You'll first need to cherry-pick these commits: > > 927609d622a3 kernel: tighten rules for ACCESS ONCE > c5b19946eb76 kernel: Fix sparse warning for ACCESS_ONCE > dd36929720f4 kernel: make READ_ONCE() valid on const arguments If you go before 3.19, you will also need 230fa253df63 kernel: Provide READ_ONCE and ASSIGN_ONCE 43239cbe79fc kernel: Change ASSIGN_ONCE(val, x) to WRITE_ONCE(x, val) > > That's the minimum set you will need for backporting, due > to overlapping changes to the ACCESS_ONCE() definition. > > and then apply this commit: > > d6abfdb20223 x86/spinlocks/paravirt: Fix memory corruption on unlock the alternative might be to replace READ_ONCE with ACCESS_ONCE when doing the backport. This depends on how important you consider backporting the ACCESS_ONCE fixes. Christian