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 D64B2ECAAA1 for ; Tue, 6 Sep 2022 17:14:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237321AbiIFROX (ORCPT ); Tue, 6 Sep 2022 13:14:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44384 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239766AbiIFRNq (ORCPT ); Tue, 6 Sep 2022 13:13:46 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1F8498E46A; Tue, 6 Sep 2022 10:03:14 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 099F9615C4; Tue, 6 Sep 2022 17:02:41 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 16118C433D6; Tue, 6 Sep 2022 17:02:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1662483760; bh=jDqY++JBkfPhBn30KMlAemUpUkKo9QHIrqZMxv95CBE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=xZl71PkmEDTHuH5uBDGlcvemDZfPv631zGaP8q+MLMSmiVmnLPJPQirop1O3qRKJe ipNrdnDK+X6r59RQgh5m6T20yDv7z+M/+TNKOHox4z6+JtbQIEh2VPeaGVKCyWXsc3 wWkr2u4nKKmH/B9Ep8uDa3WAg0rQ7EyjlqX7GqhI= Date: Tue, 6 Sep 2022 19:02:37 +0200 From: Greg Kroah-Hartman To: Phil Auld Cc: linux-kernel@vger.kernel.org, "Rafael J . Wysocki" , Barry Song <21cnbao@gmail.com>, Tian Tao , Yury Norov , feng xiangjun , stable@vger.kernel.org Subject: Re: [PATCH] drivers/base: Fix unsigned comparison to -1 in CPUMAP_FILE_MAX_BYTES Message-ID: References: <20220906160430.1169837-1-pauld@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220906160430.1169837-1-pauld@redhat.com> Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Tue, Sep 06, 2022 at 12:04:30PM -0400, Phil Auld wrote: > As PAGE_SIZE is unsigned long, -1 > PAGE_SIZE when NR_CPUS <= 3. > This leads to very large file sizes: > > topology$ ls -l > total 0 > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 core_cpus Yeah, lots of CPUs! :) > -r--r--r-- 1 root root 4096 Sep 5 11:59 core_cpus_list > -r--r--r-- 1 root root 4096 Sep 5 10:58 core_id > -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 core_siblings > -r--r--r-- 1 root root 4096 Sep 5 11:59 core_siblings_list > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 die_cpus > -r--r--r-- 1 root root 4096 Sep 5 11:59 die_cpus_list > -r--r--r-- 1 root root 4096 Sep 5 11:59 die_id > -r--r--r-- 1 root root 18446744073709551615 Sep 5 11:59 package_cpus > -r--r--r-- 1 root root 4096 Sep 5 11:59 package_cpus_list > -r--r--r-- 1 root root 4096 Sep 5 10:58 physical_package_id > -r--r--r-- 1 root root 18446744073709551615 Sep 5 10:10 thread_siblings > -r--r--r-- 1 root root 4096 Sep 5 11:59 thread_siblings_list > > Adjust the inequality to catch the case when NR_CPUS is configured > to a small value. > > Fixes: 7ee951acd31a ("drivers/base: fix userspace break from using bin_attributes for cpumap and cpulist") > Reported-by: feng xiangjun > Signed-off-by: Phil Auld > Cc: Greg Kroah-Hartman > Cc: "Rafael J. Wysocki" > Cc: Yury Norov > Cc: stable@vger.kernel.org > Cc: feng xiangjun > --- > include/linux/cpumask.h | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h > index bd047864c7ac..7b1349612d6d 100644 > --- a/include/linux/cpumask.h > +++ b/include/linux/cpumask.h > @@ -1127,9 +1127,10 @@ cpumap_print_list_to_buf(char *buf, const struct cpumask *mask, > * cover a worst-case of every other cpu being on one of two nodes for a > * very large NR_CPUS. > * > - * Use PAGE_SIZE as a minimum for smaller configurations. > + * Use PAGE_SIZE as a minimum for smaller configurations while avoiding > + * unsigned comparison to -1. > */ > -#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32 - 1) > PAGE_SIZE) \ > +#define CPUMAP_FILE_MAX_BYTES ((((NR_CPUS * 9)/32) > PAGE_SIZE + 1) \ > ? (NR_CPUS * 9)/32 - 1 : PAGE_SIZE) > #define CPULIST_FILE_MAX_BYTES (((NR_CPUS * 7)/2 > PAGE_SIZE) ? (NR_CPUS * 7)/2 : PAGE_SIZE) > > -- > 2.31.1 > Nice catch. What type of systems did you run this on to verify it will work? thanks, greg k-h