Return-Path: <linux-kernel-owner+w=401wt.eu-S1755370AbZG3AEL@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1755370AbZG3AEL (ORCPT <rfc822;w@1wt.eu>);
	Wed, 29 Jul 2009 20:04:11 -0400
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755341AbZG3AEK
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Wed, 29 Jul 2009 20:04:10 -0400
Received: from smtp1.linux-foundation.org ([140.211.169.13]:47771 "EHLO
	smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK)
	by vger.kernel.org with ESMTP id S1755321AbZG3AEJ (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Wed, 29 Jul 2009 20:04:09 -0400
Date: Wed, 29 Jul 2009 17:03:15 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-kernel@vger.kernel.org, "Eric W. Biederman" <ebiederm@xmission.com>,
       Sukadev Bhattiprolu <sukadev@us.ibm.com>,
       "Serge E. Hallyn" <serue@us.ibm.com>, Oleg Nesterov <oleg@redhat.com>
Subject: Re: Possible memory leak via alloc_pid()
Message-Id: <20090729170315.f62066c0.akpm@linux-foundation.org>
In-Reply-To: <b0943d9e0907081433y599e6d51j285c390f18d7b32c@mail.gmail.com>
References: <b0943d9e0907081433y599e6d51j285c390f18d7b32c@mail.gmail.com>
X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu)
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1784
Lines: 45

On Wed, 8 Jul 2009 22:33:31 +0100
Catalin Marinas <catalin.marinas@arm.com> wrote:

> Hi,
> 
> There's a kmemleak report of a struct pid allocation in alloc_pid()
> which somehow gets lost:
> 
> unreferenced object 0xc307aa00 (size 44):
>   comm "gdm", pid 2734, jiffies 4294902040
>   backtrace:
>     [<c01e721a>] create_object+0xfa/0x250
>     [<c01e73cd>] kmemleak_alloc+0x5d/0x70
>     [<c01e0ad6>] kmem_cache_alloc+0x156/0x1a0
>     [<c01552f9>] alloc_pid+0x19/0x350
>     [<c013e6e0>] copy_process+0x800/0x1230
>     [<c013f17f>] do_fork+0x6f/0x370
>     [<c0101986>] sys_clone+0x36/0x40
>     [<c010319c>] sysenter_do_call+0x12/0x38
>     [<ffffffff>] 0xffffffff
> 
> This is the gdm fork for starting Xorg (with pid 2739). It first
> logged me in automatically, after which I logged out and gdm started
> another Xorg. The pid structure for the first Xorg is reported as a
> leak. The Xorg with pid 2739 is no longer present on my system.
> 
> Using gdb vmlinux /proc/kcore shows that the pid->count is 2, so
> that's why it probably wasn't freed by put_pid():
> 
> (gdb) print ({struct pid}0xc307aa00)
> $20 = {count = {counter = 2}, level = 0, tasks = {{first = 0x0}, {
>       first = 0x0}, {first = 0x0}}, rcu = {next = 0xc24bfd64,
>     func = 0xc0154e90 <delayed_put_pid>}, numbers = {{nr = 2739,
>       ns = 0xc0737540, pid_chain = {next = 0x0, pprev = 0x200200}}}}
> 
> Note that kmemleak is aware of and scans pid_hash (which was recorded
> in kmemleak as a 16KB object).
> 

Thanks.  Let's cc some recent pid fiddlers.
--
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/