From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754685AbZHYIIj (ORCPT ); Tue, 25 Aug 2009 04:08:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753989AbZHYIIg (ORCPT ); Tue, 25 Aug 2009 04:08:36 -0400 Received: from courier.cs.helsinki.fi ([128.214.9.1]:54296 "EHLO mail.cs.helsinki.fi" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751851AbZHYIIf (ORCPT ); Tue, 25 Aug 2009 04:08:35 -0400 Subject: Re: WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (f6f6e1a4), by kmemleak's scan_block() From: Pekka Enberg To: Vegard Nossum Cc: Ingo Molnar , Catalin Marinas , linux-kernel@vger.kernel.org In-Reply-To: <19f34abd0908250104y6e877545y485a2104c2b97cfd@mail.gmail.com> References: <20090825071959.GA25877@elte.hu> <19f34abd0908250104y6e877545y485a2104c2b97cfd@mail.gmail.com> Date: Tue, 25 Aug 2009 11:08:36 +0300 Message-Id: <1251187716.7261.2.camel@penberg-laptop> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 7bit X-Mailer: Evolution 2.24.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Vegard, On Tue, 2009-08-25 at 10:04 +0200, Vegard Nossum wrote: > 2009/8/25 Ingo Molnar : > > > > FYI, -tip testing triggered the following kmemcheck warning in > > kmemleak: > > > > PM: Adding info for No Bus:vcsa7 > > WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (f6f6e1a4) > > d873f9f600000000c42ae4c1005c87f70000000070665f666978656400000000 > > i i i i u u u u i i i i i i i i i i i i i i i i i i i i i u u u > > ^ > > > > Pid: 3091, comm: kmemleak Not tainted (2.6.31-rc7-tip #1303) P4DC6 > > EIP: 0060:[] EFLAGS: 00010006 CPU: 0 > > EIP is at scan_block+0x3f/0xe0 > > EAX: f40bd700 EBX: f40bd780 ECX: f16b46c0 EDX: 00000001 > > ESI: f6f6e1a4 EDI: 00000000 EBP: f10f3f4c ESP: c2605fcc > > DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068 > > CR0: 8005003b CR2: e89a4844 CR3: 30ff1000 CR4: 000006f0 > > DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 > > DR6: ffff4ff0 DR7: 00000400 > > [] scan_object+0x7c/0xf0 > > [] kmemleak_scan+0x1d9/0x400 > > [] kmemleak_scan_thread+0x4c/0xb0 > > [] kthread+0x74/0x80 > > [] kernel_thread_helper+0x7/0x3c > > [] 0xffffffff > > kmemleak: 515 new suspected memory leaks (see /sys/kernel/debug/kmemleak) > > kmemleak: 42 new suspected memory leaks (see /sys/kernel/debug/kmemleak) > > > > config attached. (And this is the first documented case of a kmem > > civil war i guess ;-) > > Already the patch to make kmemcheck and kmemleak mutually exclusive is > underway. It is not surprising that kmemleak is scanning uninitialized > memory. But if you say that you have tried it before, it is strange > that it didn't appear until now. Why isn't it surprising? Yes, it's non-fatal for kmemleak to scan uninitialized memory but we could be looking at non-initialized struct member that's a bug waiting to happen elsewhere in the code (that doesn't trigger often). Pekka