From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932454AbdJJPxA (ORCPT ); Tue, 10 Oct 2017 11:53:00 -0400 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:47006 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932142AbdJJPw7 (ORCPT ); Tue, 10 Oct 2017 11:52:59 -0400 From: Jeremy Linton To: linux-kernel@vger.kernel.org Cc: peterz@infradead.org, mingo@redhat.com, Jeremy Linton Subject: [PATCH] locktorture: Fix Oops when reader/writer count is 0 Date: Tue, 10 Oct 2017 10:52:48 -0500 Message-Id: <20171010155248.11602-1-jeremy.linton@arm.com> X-Mailer: git-send-email 2.13.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If nwriters_stress=0 is passed to the lock torture test it will panic in: 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; -- 2.13.5