From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751298Ab1GREH7 (ORCPT ); Mon, 18 Jul 2011 00:07:59 -0400 Received: from gate.crashing.org ([63.228.1.57]:45245 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750725Ab1GREHy (ORCPT ); Mon, 18 Jul 2011 00:07:54 -0400 Subject: Re: [PATCH 1/1] Fixup write permission of TLB on powerpc e500 core From: Benjamin Herrenschmidt To: Peter Zijlstra Cc: Shan Hai , Peter Zijlstra , paulus@samba.org, tglx@linutronix.de, walken@google.com, dhowells@redhat.com, cmetcalf@tilera.com, tony.luck@intel.com, akpm@linux-foundation.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org In-Reply-To: <1310961196.25044.266.camel@pasglop> References: <1310717238-13857-1-git-send-email-haishan.bai@gmail.com> <1310717238-13857-2-git-send-email-haishan.bai@gmail.com> <1310725418.2586.309.camel@twins> <4E21A526.8010904@gmail.com> <1310860194.25044.17.camel@pasglop> <4b337921-d430-4b63-bc36-ad31753cf800@email.android.com> <1310912990.25044.203.camel@pasglop> <1310944453.25044.262.camel@pasglop> <1310961196.25044.266.camel@pasglop> Content-Type: text/plain; charset="UTF-8" Date: Mon, 18 Jul 2011 14:02:23 +1000 Message-ID: <1310961743.25044.275.camel@pasglop> Mime-Version: 1.0 X-Mailer: Evolution 2.30.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2011-07-18 at 13:53 +1000, Benjamin Herrenschmidt wrote: > On Mon, 2011-07-18 at 09:14 +1000, Benjamin Herrenschmidt wrote: > > > In fact, with such a flag, we could probably avoid the ifdef entirely, and > > always go toward the PTE fixup path when called in such a fixup case, my gut > > feeling is that this is going to be seldom enough not to hurt x86 measurably > > but we'll have to try it out. > > > > That leads to that even less tested patch: > > And here's a version that builds (still not tested :-) > > Shan, can you verify whether that fixes the problem for you ? > > I also had a cursory glance at the ARM code and it seems to rely on the > same stuff as embedded powerpc does for dirty/young updates, so in > theory it should exhibit the same problem. > > I suspect the scenario is rare enough in practice in embedded workloads > that nobody noticed until now. Ignore that bogus send, I sent a proper one immediately after (evolution FAIL, sorry about that) Cheers, Ben.