Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753454AbaG3MSA (ORCPT ); Wed, 30 Jul 2014 08:18:00 -0400 Received: from ip4-83-240-18-248.cust.nbox.cz ([83.240.18.248]:36858 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753067AbaG3MPf (ORCPT ); Wed, 30 Jul 2014 08:15:35 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Mateusz Guzik , Peter Zijlstra , Linus Torvalds , Ingo Molnar , Jiri Slaby Subject: [PATCH 3.12 72/94] sched: Fix possible divide by zero in avg_atom() calculation Date: Wed, 30 Jul 2014 14:15:01 +0200 Message-Id: <9f8d4874814497d7dc0d92f19a1680a0afde1ecc.1406722270.git.jslaby@suse.cz> X-Mailer: git-send-email 2.0.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Mateusz Guzik 3.12-stable review patch. If anyone has any objections, please let me know. =============== commit b0ab99e7736af88b8ac1b7ae50ea287fffa2badc upstream. proc_sched_show_task() does: if (nr_switches) do_div(avg_atom, nr_switches); nr_switches is unsigned long and do_div truncates it to 32 bits, which means it can test non-zero on e.g. x86-64 and be truncated to zero for division. Fix the problem by using div64_ul() instead. As a side effect calculations of avg_atom for big nr_switches are now correct. Signed-off-by: Mateusz Guzik Signed-off-by: Peter Zijlstra Cc: Linus Torvalds Link: http://lkml.kernel.org/r/1402750809-31991-1-git-send-email-mguzik@redhat.com Signed-off-by: Ingo Molnar Signed-off-by: Jiri Slaby --- kernel/sched/debug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index fd9ca1de7559..0efe4a27540b 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -554,7 +554,7 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m) avg_atom = p->se.sum_exec_runtime; if (nr_switches) - do_div(avg_atom, nr_switches); + avg_atom = div64_ul(avg_atom, nr_switches); else avg_atom = -1LL; -- 2.0.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/