From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E81D5C7EE23 for ; Wed, 31 May 2023 12:22:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235145AbjEaMWN (ORCPT ); Wed, 31 May 2023 08:22:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33078 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229765AbjEaMWJ (ORCPT ); Wed, 31 May 2023 08:22:09 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 4FFD5134 for ; Wed, 31 May 2023 05:22:05 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 64FEB1042; Wed, 31 May 2023 05:22:50 -0700 (PDT) Received: from bogus (e103737-lin.cambridge.arm.com [10.1.197.49]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2C3F63F67D; Wed, 31 May 2023 05:22:04 -0700 (PDT) Date: Wed, 31 May 2023 13:22:01 +0100 From: Sudeep Holla To: Ricardo Neri Cc: Radu Rendec , linux-kernel@vger.kernel.org, Sudeep Holla , Pierre Gondois , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v4 1/3] cacheinfo: Add arch specific early level initializer Message-ID: <20230531122201.3n3ak5n3cjisbmtm@bogus> References: <20230412185759.755408-1-rrendec@redhat.com> <20230412185759.755408-2-rrendec@redhat.com> <20230510191207.GA18514@ranerica-svr.sc.intel.com> <20230515093608.etfprpqn3lmgybe6@bogus> <20230518012703.GA19967@ranerica-svr.sc.intel.com> <20230518093414.qhwyogcig4wv3r5s@bogus> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230518093414.qhwyogcig4wv3r5s@bogus> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 18, 2023 at 10:34:14AM +0100, Sudeep Holla wrote: > On Wed, May 17, 2023 at 06:27:03PM -0700, Ricardo Neri wrote: > > On Mon, May 15, 2023 at 10:36:08AM +0100, Sudeep Holla wrote: > > > On Wed, May 10, 2023 at 12:12:07PM -0700, Ricardo Neri wrote: > > > > Hi, > > > > > > > > I had posted a patchset[1] for x86 that initializes > > > > ci_cacheinfo(cpu)->num_leaves during SMP boot. > > > > > > > > > > It is entirely clear to me if this is just a clean up or a fix to some > > > issue you faced ? Just wanted to let you know Prateek from AMD has couple > > > of fixes [2] > > > > My first patch is a bug fix. The second patch is clean up that results > > from fixing the bug in patch 1. > > > > > > > > > This means that early_leaves and a late cache_leaves() are equal but > > > > per_cpu_cacheinfo(cpu) is never allocated. Currently, x86 does not use > > > > fetch_cache_info(). > > > > > > > > I think that we should check here that per_cpu_cacheinfo() has been allocated to > > > > take care of the case in which early and late cache leaves remain the same: > > > > > > > > - if (cache_leaves(cpu) <= early_leaves) > > > > + if (cache_leaves(cpu) <= early_leaves && per_cpu_cacheinfo(cpu)) > > > > > > > > Otherwise, in v6.4-rc1 + [1] I observe a NULL pointer dereference from > > > > last_level_cache_is_valid(). > > > > > > > > > > I think this is different issue as Prateek was just observing wrong info > > > after cpuhotplug operations. But the patches manage the cpumap_populated > > > state better with the patches. Can you please look at that as weel ? > > > > I verified that the patches from Prateek fix a different issue. I was able > > to reproduce his issue. His patches fixes it. > > > > I still see my issue after applying Prateek's patches. > > Thanks, I thought it is different issue and good that you were able to test > them as well. Please post a proper patch for the NULL ptr dereference you > are hitting on x86. Gentle ping! Are you still observing NULL ptr dereference with v6.4-rcx ? If so, can you please post the fix as a proper patch ? Some of the patches in v6.4-rc1 are being backported, so I prefer to have all the known issues fixed before that happens. Sorry for the nag, but backport is the reason I am pushing for this. -- Regards, Sudeep