From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753553Ab2JVL4L (ORCPT ); Mon, 22 Oct 2012 07:56:11 -0400 Received: from rcsinet15.oracle.com ([148.87.113.117]:33659 "EHLO rcsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752922Ab2JVL4J (ORCPT ); Mon, 22 Oct 2012 07:56:09 -0400 Date: Mon, 22 Oct 2012 14:55:46 +0300 From: Dan Carpenter To: a.p.zijlstra@chello.nl Cc: linux-kernel@vger.kernel.org Subject: re: sched, numa, mm: Implement constant, per task Working Set Sampling (WSS) rate Message-ID: <20121022115545.GA631@elgon.mountain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Peter Zijlstra, The patch 3d049f8a5398: "sched, numa, mm: Implement constant, per task Working Set Sampling (WSS) rate" from Oct 14, 2012, leads to the following warning: kernel/sched/fair.c:954 task_numa_work() error: we previously assumed 'vma' could be null (see line 948) 943 if (!vma) { 944 ACCESS_ONCE(mm->numa_scan_seq)++; 945 offset = 0; 946 vma = mm->mmap; 947 } 948 while (vma && !vma_migratable(vma)) { ^^^ If this is NULL, 949 vma = vma->vm_next; 950 if (!vma) 951 goto again; 952 } 953 954 offset = max(offset, vma->vm_start); ^^^^^^^^^^^^^ then it leads to a NULL dereference here. regards, dan carpenter