Return-Path: linux-nfs-owner@vger.kernel.org Received: from mail-ye0-f182.google.com ([209.85.213.182]:63356 "EHLO mail-ye0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753391Ab3CEXrE (ORCPT ); Tue, 5 Mar 2013 18:47:04 -0500 Date: Tue, 5 Mar 2013 15:47:00 -0800 From: Tejun Heo To: Jeff Layton Cc: "Myklebust, Trond" , Oleg Nesterov , Mandeep Singh Baines , Ming Lei , "J. Bruce Fields" , Linux Kernel Mailing List , "linux-nfs@vger.kernel.org" , "Rafael J. Wysocki" , Andrew Morton , Ingo Molnar , Al Viro Subject: Re: LOCKDEP: 3.9-rc1: mount.nfs/4272 still has locks held! Message-ID: <20130305234700.GE1227@htj.dyndns.org> References: <20130304092310.1d21100c@tlielax.poochiereds.net> <20130304205307.GA13527@redhat.com> <4FA345DA4F4AE44899BD2B03EEEC2FA9286AEEB0@sacexcmbx05-prd.hq.netapp.com> <20130305082308.6607d4db@tlielax.poochiereds.net> <20130305174648.GF12795@htj.dyndns.org> <20130305174954.GG12795@htj.dyndns.org> <20130305140312.243cb094@tlielax.poochiereds.net> <20130305190923.GI12795@htj.dyndns.org> <20130305183941.19ff39ce@tlielax.poochiereds.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <20130305183941.19ff39ce@tlielax.poochiereds.net> Sender: linux-nfs-owner@vger.kernel.org List-ID: Hello, Jeff. On Tue, Mar 05, 2013 at 06:39:41PM -0500, Jeff Layton wrote: > Al was in the middle of his signal handling/execve rework though and I > ran the idea past him. He pointedly told me that I was crazy for even > considering it. This is rather non-trivial to handle since it means > mucking around in a bunch of arch-specific code and dealing with all of > the weirdo corner cases. Hmmm... I tried it a couple years ago while I was working on ptrace improvements to support checkpoint-restart in userland (PTRACE_SEIZE and friends) and had a half-working code. At the time, Oleg was against the idea and something else came up so I didn't push it all the way but IIRC it didn't need to touch any arch code. It should be able to just share the existing trap path with ptrace. > Anyone up for working out how to handle a freeze event on a process > that already has a pending signal, while it's being ptraced? It's > probably best to chat with Al (cc'ed here) before you embark on this > plan since he was just in that code recently. Maybe Al sees something that I don't but AFAICS it should be doable in generic code proper and I don't think it's gonna be that hard. Oleg, are you still opposed to the idea of making freezer share trap points with ptrace? Thanks. -- tejun