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 AB222C38145 for ; Tue, 6 Sep 2022 17:31:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239439AbiIFRbb (ORCPT ); Tue, 6 Sep 2022 13:31:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53094 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233679AbiIFRat (ORCPT ); Tue, 6 Sep 2022 13:30:49 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6241027CD5 for ; Tue, 6 Sep 2022 10:24:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1662485090; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=8jj5ltO1LOk0SlLaaEAJAylbk3vvryd3UX57GATziA8=; b=EyN/11aCfOMZnqYSK9YxRMPL9AF80mQdtDacyTss56MGInbR9qZ1//AYAD4HKTHT9ROD8x 9ZyhUco5e0D/xQkV/lGN4VIFPt4edX8ulJrX9ikZJScVYm/+m/6Qv8E4gfWovI9AlVzjHv gaHjEUY8jNTVdHe6EdgtUBvvIsc6INo= Received: from mimecast-mx02.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-45-x_4o4RaGNtOjYIbWvCLvmQ-1; Tue, 06 Sep 2022 13:24:46 -0400 X-MC-Unique: x_4o4RaGNtOjYIbWvCLvmQ-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2BDD7382ECC1; Tue, 6 Sep 2022 17:24:46 +0000 (UTC) Received: from lorien.usersys.redhat.com (unknown [10.22.32.243]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BF4D32166B26; Tue, 6 Sep 2022 17:24:45 +0000 (UTC) Date: Tue, 6 Sep 2022 13:24:44 -0400 From: Phil Auld To: Greg Kroah-Hartman 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: X-Scanned-By: MIMEDefang 2.78 on 10.11.54.6 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Tue, Sep 06, 2022 at 07:02:37PM +0200 Greg Kroah-Hartman wrote: > 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! :) > Yep, apparently things like lscpu fail with this size. > > -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? > Feng ran it on his 2 cpu laptop. I ran it on my usual test bed (80 cpus) but configured both with NR_CPUS at 8192 and at 2. It's not really dependent on the actual system. It's a compile time config option. I failed to set it small when testing the first one. The fix here is just maths :) With NR_CPUS == 2: # ls -l /sys/devices/system/cpu/cpu0/topology/ total 0 -r--r--r--. 1 root root 4096 Sep 6 11:40 cluster_cpus -r--r--r--. 1 root root 4096 Sep 6 11:40 cluster_cpus_list -r--r--r--. 1 root root 4096 Sep 6 11:40 cluster_id -r--r--r--. 1 root root 4096 Sep 6 11:40 core_cpus -r--r--r--. 1 root root 4096 Sep 6 11:40 core_cpus_list -r--r--r--. 1 root root 4096 Sep 6 11:40 core_id -r--r--r--. 1 root root 4096 Sep 6 11:29 core_siblings -r--r--r--. 1 root root 4096 Sep 6 11:40 core_siblings_list ... Cheers, Phil > thanks, > > greg k-h > --