Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758129Ab1DLQTR (ORCPT ); Tue, 12 Apr 2011 12:19:17 -0400 Received: from mail-px0-f179.google.com ([209.85.212.179]:34010 "EHLO mail-px0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758114Ab1DLQTQ convert rfc822-to-8bit (ORCPT ); Tue, 12 Apr 2011 12:19:16 -0400 MIME-Version: 1.0 In-Reply-To: References:

Date: Tue, 12 Apr 2011 18:17:45 +0200 Message-ID: Subject: Re: [PATCH] mm: fix possible cause of a page_mapped BUG From: =?UTF-8?B?Um9iZXJ0IMWad2nEmWNraQ==?= To: Linus Torvalds Cc: Hugh Dickins , Andrew Morton , Miklos Szeredi , Michel Lespinasse , "Eric W. Biederman" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Peter Zijlstra , Rik van Riel Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1955 Lines: 54 >>> So, if this case is not caught later on in the code, I guess it solves >>> the problem. During the fuzzing I didn't experience any panic's, but >>> some other problems arose, i.e. cannot read /proc//maps for some >>> processes (sys_read hangs, and such process cannot be killed or >>> stopped with any signal, still it's running (R state) and using CPU - >>> I'll submit another report for that). >> >> Hmm. Sounds like an endless loop in kernel mode. >> >> Use "perf record -ag" as root, it should show up very clearly in the report. >> >> Linus > > I've put some data here - > http://groups.google.com/group/fa.linux.kernel/browse_thread/thread/4345dcc4f7750ce2 > - I think it's somewhat connected (sys_mlock appears on both cases). > > Attaching perf data (for 2.6.38) + kdb dumpall + procdump for process 14158 > > Those 3 processes cannot be stopped/killed > > 14158 66.2 0.0 8380 3012 ? RL /tmp/iknowthis > 17100 63.6 0.1 18248 4004 ? RL /tmp/iknowthis > 19772 63.8 0.0 4000 1888 ? RL /tmp/iknowthis Also, the system doesn't look usable after such fuzzing (executing a few times some pretty deterministic program) root@ise-test:~# gcc -m32 mlock.c -o mlock root@ise-test:~# ./mlock ./mlock: relocation error: ./mlock: symbol perror, version GLIBC_2.0 not defined in file libc.so.6 with link time reference root@ise-test:~# ./mlock mmap: Success RET: 0xf751f000 mremap: Invalid argument RET: 0xffffffff root@ise-test:~# ./mlock Segmentation fault root@ise-test:~# dmesg | tail -n 1 [ 5164.961568] mlock[7097]: segfault at 0 ip (null) sp 00000000ff8a00d4 error 14 in mlock[8048000+1000] -- Robert Święcki -- 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/