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 A9176C54EE9 for ; Thu, 22 Sep 2022 12:40:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230265AbiIVMkL (ORCPT ); Thu, 22 Sep 2022 08:40:11 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38886 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229762AbiIVMkI (ORCPT ); Thu, 22 Sep 2022 08:40:08 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 48A5170E6C for ; Thu, 22 Sep 2022 05:40:05 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 9AF60B8362F for ; Thu, 22 Sep 2022 12:40:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E92E0C433C1; Thu, 22 Sep 2022 12:40:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1663850403; bh=OmOE0nh7bHVmof8ZvHEBC68t4a89rpX3I6KpWBI4zis=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=HFpmc9olMJ/X9umMTl3oTOasfy4xDO+ZTP4kLThzXPg+vJXtLernHWXQyKi9f9lPZ 3enwGGOLcqaex+lUKdoHyeHdFN8MVWgZg5ujLOjuUDFk4LSz9th71ifEHJnIC+lBkA SS27gs+U8lX+Ml2DXSUkTxMF8KVTFkU2Ln44wXUM= Date: Thu, 22 Sep 2022 14:40:00 +0200 From: Greg Kroah-Hartman To: Phil Auld Cc: Petr =?utf-8?Q?=C5=A0tetiar?= , linux-kernel@vger.kernel.org, yury.norov@gmail.com, rafael@kernel.org Subject: Re: aarch64 5.15.68 regression in topology/thread_siblings (huge file size and no content) Message-ID: References: <20220922113217.GA90426@meh.true.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Sep 22, 2022 at 08:32:10AM -0400, Phil Auld wrote: > On Thu, Sep 22, 2022 at 01:32:17PM +0200 Petr Štetiar wrote: > > Hi, > > > > we've got a recent bug report[1], that lscpu segfaults on aarch64 board running > > 5.15.y kernel. It is working fine on 5.10.y kernel. > > > > I've tracked it down[2] to the issue with `topology/thread_siblings` which > > apart from very strange file size returns empty content. I assume, that it's > > somehow related to the changes done in commit bb9ec13d156e ("topology: use > > bin_attribute to break the size limitation of cpumap ABI"), but I didn't tried > > to revert it yet to verify it. > > > > This is actually due to a fix for that since returning 0 size breaks > things as well. > > 7ee951acd31a drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist > > The fix for small number of cpus as you have is now in Greg's driver core tree > > d7f06bdd6ee8 drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES > > and should work it's way back to stable trees soon. That should fix up the file size issue. The main problem being reported here is: > > Kernel 5.15.68: > > > > root@OpenWrt:/# uname -a > > Linux OpenWrt 5.15.68 #0 SMP Wed Sep 21 05:54:21 2022 aarch64 GNU/Linux > > > > root@OpenWrt:/# find /sys -name thread_siblings -exec ls -al {} \; > > -r--r--r-- 1 root root 18446744073709551615 Sep 22 08:37 /sys/devices/system/cpu/cpu1/topology/thread_siblings > > -r--r--r-- 1 root root 18446744073709551615 Sep 22 08:37 /sys/devices/system/cpu/cpu0/topology/thread_siblings > > > > root@OpenWrt:/# find /sys -name thread_siblings -exec cat {} \; > > root@OpenWrt:/# Nothing in the file in 5.15, yet 5.10: > > > > Kernel 5.10.138: > > > > root@OpenWrt:/# uname -a > > Linux OpenWrt 5.10.138 #0 SMP Sat Sep 3 02:55:34 2022 aarch64 GNU/Linux > > > > root@OpenWrt:/# find /sys -name thread_siblings -exec cat {} \; > > 2 > > 1 Has data in the files. What caused that change? thanks, greg k-h