Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757554Ab1FPKCV (ORCPT ); Thu, 16 Jun 2011 06:02:21 -0400 Received: from e6.ny.us.ibm.com ([32.97.182.146]:50174 "EHLO e6.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756991Ab1FPKCT (ORCPT ); Thu, 16 Jun 2011 06:02:19 -0400 Date: Thu, 16 Jun 2011 15:24:12 +0530 From: Srikar Dronamraju To: Peter Zijlstra Cc: Ingo Molnar , Steven Rostedt , Linux-mm , Arnaldo Carvalho de Melo , Linus Torvalds , Ananth N Mavinakayanahalli , Hugh Dickins , Christoph Hellwig , Jonathan Corbet , Thomas Gleixner , Masami Hiramatsu , Oleg Nesterov , Andrew Morton , Jim Keniston , Roland McGrath , Andi Kleen , LKML Subject: Re: [PATCH v4 3.0-rc2-tip 4/22] 4: Uprobes: register/unregister probes. Message-ID: <20110616095412.GK4952@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <20110607125804.28590.92092.sendpatchset@localhost6.localdomain6> <20110607125900.28590.16071.sendpatchset@localhost6.localdomain6> <1308159719.2171.57.camel@laptop> <20110616041137.GG4952@linux.vnet.ibm.com> <1308217582.15315.94.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1308217582.15315.94.camel@twins> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2618 Lines: 68 * Peter Zijlstra [2011-06-16 11:46:22]: > On Thu, 2011-06-16 at 09:41 +0530, Srikar Dronamraju wrote: > > * Peter Zijlstra [2011-06-15 19:41:59]: > > > > > On Tue, 2011-06-07 at 18:29 +0530, Srikar Dronamraju wrote: > > > > 1. Use mm->owner and walk thro the thread_group of mm->owner, siblings > > > > of mm->owner, siblings of parent of mm->owner. This should be > > > > good list to traverse. Not sure if this is an exhaustive > > > > enough list that all tasks that have a mm set to this mm_struct are > > > > walked through. > > > > > > As per copy_process(): > > > > > > /* > > > * Thread groups must share signals as well, and detached threads > > > * can only be started up within the thread group. > > > */ > > > if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND)) > > > return ERR_PTR(-EINVAL); > > > > > > /* > > > * Shared signal handlers imply shared VM. By way of the above, > > > * thread groups also imply shared VM. Blocking this case allows > > > * for various simplifications in other code. > > > */ > > > if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM)) > > > return ERR_PTR(-EINVAL); > > > > > > CLONE_THREAD implies CLONE_VM, but not the other way around, we > > > therefore would be able to CLONE_VM and not be part of the primary > > > owner's thread group. > > > > > > This is of course all terribly sad.. > > > > Agree, > > > > If clone(CLONE_VM) were to be done by a thread_group leader, we can walk > > thro the siblings of parent of mm->owner. > > > > However if clone(CLONE_VM) were to be done by non thread_group_leader > > thread, then we dont even seem to add it to the init_task. i.e I dont > > think we can refer to such a thread even when we walk thro > > do_each_thread(g,t) { .. } while_each_thread(g,t); > > > > right? > > No, we initialize p->group_leader = p; and only change that for > CLONE_THREAD, so a clone without CLONE_THREAD always results in a new > thread group leader, which are always added to the init_task list. > Ahh .. I missed the p->group_leader = p thing. In which case, shouldnt traversing all the tasks of all siblings of parent of mm->owner should provide us all the the tasks that have linked to mm. Right? Agree that we can bother about this a little later. -- Thanks and Regards Srikar -- 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/