From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mathieu Desnoyers Subject: Re: linux-next: manual merge of the rcu tree with the tip tree Date: Tue, 1 Aug 2017 00:04:05 +0000 (UTC) Message-ID: <1145333348.610.1501545845911.JavaMail.zimbra@efficios.com> References: <20170731135029.479025ea@canb.auug.org.au> <20170731161341.GG3730@linux.vnet.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170731161341.GG3730@linux.vnet.ibm.com> Sender: linux-kernel-owner@vger.kernel.org To: "Paul E. McKenney" Cc: Stephen Rothwell , Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Peter Zijlstra , Linux-Next Mailing List , linux-kernel , Andy Lutomirski List-Id: linux-next.vger.kernel.org ----- On Jul 31, 2017, at 12:13 PM, Paul E. McKenney paulmck@linux.vnet.ibm.com wrote: > On Mon, Jul 31, 2017 at 01:50:29PM +1000, Stephen Rothwell wrote: >> Hi Paul, >> >> Today's linux-next merge of the rcu tree got a conflict in: >> >> arch/x86/mm/tlb.c >> >> between commit: >> >> 94b1b03b519b ("x86/mm: Rework lazy TLB mode and TLB freshness tracking") >> >> from the tip tree and commit: >> >> d7713e8f8b23 ("membarrier: Expedited private command") >> >> from the rcu tree. >> >> I fixed it up (the former removed the comment and the load_cr3(), so I >> just dropped the commend change in the latter) and can carry the fix as >> necessary. This is now fixed as far as linux-next is concerned, but any >> non trivial conflicts should be mentioned to your upstream maintainer >> when your tree is submitted for merging. You may also want to consider >> cooperating with the maintainer of the conflicting tree to minimise any >> particularly complex conflicts. > > Thank you, Stephen! > > Mathieu, Peter, our commit log reads as if removal of load_cr3() would > simply result in relying on the ordering provided by the atomic ops > in switch_mm() for mm_cpumask(), so that only the commit log and the > comment need changing. > > Please let me know if I am missing something here. I think you are right. Both load_cr3() and mm_cpumask update operations (LOCK prefixed) provide the appropriate barriers on x86. So it's just a matter of adapting the comment to the new reality. Thanks, Mathieu > > Thanx, Paul -- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com