From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757983AbZKFBEJ (ORCPT ); Thu, 5 Nov 2009 20:04:09 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756462AbZKFBEI (ORCPT ); Thu, 5 Nov 2009 20:04:08 -0500 Received: from terminus.zytor.com ([198.137.202.10]:44147 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753622AbZKFBEH (ORCPT ); Thu, 5 Nov 2009 20:04:07 -0500 Message-ID: <4AF37600.9030706@zytor.com> Date: Thu, 05 Nov 2009 17:04:00 -0800 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.4pre) Gecko/20091014 Fedora/3.0-2.8.b4.fc11 Thunderbird/3.0b4 MIME-Version: 1.0 To: Alan Cox , Sukadev Bhattiprolu CC: LKML , Greg KH Subject: Re: /proc/sys/kernel/pty/nr broken, possibly since 2.6.28 References: <4AF364F3.4070300@zytor.com> In-Reply-To: <4AF364F3.4070300@zytor.com> 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 On 11/05/2009 03:51 PM, H. Peter Anvin wrote: > I just noticed that /proc/sys/kernel/pty/nr is broken, and the most > likely culprit seems to be the series of checkins that include 8b0a88d5 > and bf970ee4, during the 2.6.28 merge window. This is thus a > regression. I haven't verified that the bug really goes that far back > -- I should do a bisection -- but it is at least present in 2.6.30.9 and > 2.6.32-rc6. > > The symptom is that /proc/sys/kernel/pty/nr is properly increased, but > never decreased when a pty gets dropped. It is in fact rather trivial > to escalate /proc/sys/kernel/pty/nr far above /proc/sys/kernel/pty/max. > > As far as I read this series, the indent was to have this accounting > handled in pty_unix98_remove(), however, it would appear that that > function never gets called. I'm wondering if this may be a symptom of a > bigger problem as well. > Bisection confirms that the bug was introduced during this commit series: There are only 'skip'ped commit left to test. The first bad commit could be any of: 8b0a88d5912ab549d5adac2c8498ecdaae5319a5 73ec06fc5f5c8e1097a7a4a4ab2d7c6c3a007e81 7d7b93c1452f381350dbaf276a63357fa6559e6d bf970ee46e0fb363c8df4393229121d54330a98e We cannot bisect more! This series of skipped commits are ones during which /proc/sys/kernel/pty doesn't exist at all. -hpa