From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754467AbZBUWUR (ORCPT ); Sat, 21 Feb 2009 17:20:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755206AbZBUWTy (ORCPT ); Sat, 21 Feb 2009 17:19:54 -0500 Received: from mail-fx0-f164.google.com ([209.85.220.164]:62069 "EHLO mail-fx0-f164.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754726AbZBUWTx (ORCPT ); Sat, 21 Feb 2009 17:19:53 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=sFopXSLleIqxeVpCoaOrEp0gZ1sdJrcI4E2Fl+f1hqQatELTbdDtP05cESDKJBioIo 97DkW6UFkGxBtMMNRwxgO188pyYdabKpwKYl2jeo+3YTABMedS0wCVGtXAYEqKyI8Vy0 K9ThGej7d9MegBTjiqgD0M9MI6poVoGB+GZ74= MIME-Version: 1.0 In-Reply-To: <19f34abd0902211332r6fd0a1e3l3cee6c49e85f879e@mail.gmail.com> References: <20090221211908.GA6798@silver.sucs.org> <19f34abd0902211332r6fd0a1e3l3cee6c49e85f879e@mail.gmail.com> Date: Sat, 21 Feb 2009 23:19:50 +0100 Message-ID: <19f34abd0902211419p4109f8bfsf987b68162b01f50@mail.gmail.com> Subject: Re: Is kmemcheck currently broken on tip? From: Vegard Nossum To: Sitsofe Wheeler Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Pekka Enberg Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2009/2/21 Vegard Nossum : > 2009/2/21 Sitsofe Wheeler : >> Hi, >> >> I've been trying to test kmemcheck in linux-tip on my EeePC and things >> have been going suspiciously not so slow with little extra memory used >> (at least compared to the last time I used kmemcheck). While I see >> [ 0.063412] kmemcheck: "Bugs, beware!" >> in dmesg, I'm not sure kmemcheck is working especially since nothing is >> flagged when I trigger the issue described in >> http://marc.info/?l=linux-kernel&m=123472656015761&w=1 ... > > Thanks for the tip! :-D I get this: > ... > (Hm, maybe storing the unreliable stack frames wasn't such a good idea > at all -- all they do is fill up the space.) > A different one, with more stack: [ 352.792672] WARNING: kmemcheck: Caught 8-bit read from uninitialized memory ( f54fb0b8) [ 352.801437] 2e76b5343061aa6a6fc5db64689d95188383de4b60554e79ffffffffffffffff [ 352.828424] i i i i i i i i i i i i i i i i i i i i i i i i u u u u u u u u [ 352.855402] ^ [ 352.861954] [ 352.864110] Pid: 2414, comm: cat Not tainted (2.6.29-rc4 #251) 945P-A [ 352.871286] EIP: 0060:[] EFLAGS: 00010297 CPU: 0 [ 352.877479] EIP is at strnlen+0x9/0x20 [ 352.881904] EAX: f54fb0b8 EBX: c162081e ECX: f54fb000 EDX: ffffff46 [ 352.888900] ESI: ffffffff EDI: f54fb000 EBP: f552bd8c ESP: c17866e4 [ 352.895897] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 [ 352.902012] CR0: 8005003b CR2: f6c04070 CR3: 354fa000 CR4: 000006d0 [ 352.909009] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000 [ 352.916006] DR6: ffff4ff0 DR7: 00000400 [ 353.023259] [] string+0x28/0xd0 [ 353.029382] [] vsnprintf+0x484/0xac0 [ 353.164334] [] sprintf+0x1c/0x20 [ 353.170556] [] param_get_charp+0x1f/0x30 [ 353.177475] [] param_attr_show+0x22/0x50 [ 353.191231] [] module_attr_show+0x28/0x40 [ 353.198241] [] sysfs_read_file+0x7d/0x110 [ 353.205246] [] vfs_read+0x99/0x160 [ 353.218557] [] sys_read+0x3d/0x70 [ 353.224846] [] sysenter_do_call+0x12/0x21 [ 353.231857] [] 0xffffffff That's where it happened: $ addr2line -e vmlinux -i c11a76e9 c11a64a8 c11a69d4 c11a702c c10443ff c1044152 c1043d88 c10efbad c10a52d9 c10a545d arch/x86/lib/string_32.c:222 lib/vsprintf.c:524 lib/vsprintf.c:846 lib/vsprintf.c:1058 kernel/params.c:227 kernel/params.c:407 kernel/params.c:671 fs/sysfs/file.c:92 fs/sysfs/file.c:142 fs/read_write.c:292 fs/read_write.c:369 fs/read_write.c:382 (Code is -rc4) Hope this helps, if you didn't sort it out already :-) Vegard -- "The animistic metaphor of the bug that maliciously sneaked in while the programmer was not looking is intellectually dishonest as it disguises that the error is the programmer's own creation." -- E. W. Dijkstra, EWD1036