From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932580AbdKGUCK (ORCPT ); Tue, 7 Nov 2017 15:02:10 -0500 Received: from foss.arm.com ([217.140.101.70]:53678 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932490AbdKGUCH (ORCPT ); Tue, 7 Nov 2017 15:02:07 -0500 Subject: Re: [PATCH] locktorture: Fix Oops when reader/writer count is 0 To: linux-kernel@vger.kernel.org Cc: peterz@infradead.org, mingo@redhat.com References: <20171010155248.11602-1-jeremy.linton@arm.com> From: Jeremy Linton Message-ID: Date: Tue, 7 Nov 2017 14:01:58 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <20171010155248.11602-1-jeremy.linton@arm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 10/10/2017 10:52 AM, Jeremy Linton wrote: > If nwriters_stress=0 is passed to the lock torture test > it will panic in: Ping? Has anyone had a chance to look at this? Thanks, > > Internal error: Oops: 96000005 [#1] SMP > ... > [] __torture_print_stats+0x2c/0x1c8 [locktorture] > [] lock_torture_stats_print+0x74/0x120 [locktorture] > [] lock_torture_stats+0x40/0xa8 [locktorture] > [] kthread+0x108/0x138 > [] ret_from_fork+0x10/0x18 > > This is caused by the deference to a null statp. Fix that by > checking the n_stress for non zero count before referencing statp. > > Signed-off-by: Jeremy Linton > --- > kernel/locking/locktorture.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/kernel/locking/locktorture.c b/kernel/locking/locktorture.c > index f24582d4dad3..8229ba7147e5 100644 > --- a/kernel/locking/locktorture.c > +++ b/kernel/locking/locktorture.c > @@ -716,10 +716,14 @@ static void __torture_print_stats(char *page, > bool fail = 0; > int i, n_stress; > long max = 0; > - long min = statp[0].n_lock_acquired; > + long min = 0; > long long sum = 0; > > n_stress = write ? cxt.nrealwriters_stress : cxt.nrealreaders_stress; > + > + if (n_stress) > + min = statp[0].n_lock_acquired; > + > for (i = 0; i < n_stress; i++) { > if (statp[i].n_lock_fail) > fail = true; >