From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756185Ab2DNUxE (ORCPT ); Sat, 14 Apr 2012 16:53:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:11067 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755951Ab2DNUxB (ORCPT ); Sat, 14 Apr 2012 16:53:01 -0400 Date: Sat, 14 Apr 2012 22:52:00 +0200 From: Oleg Nesterov To: Peter Zijlstra Cc: Ingo Molnar , Srikar Dronamraju , Andrew Morton , Linus Torvalds , Ananth N Mavinakayanahalli , Jim Keniston , LKML , Linux-mm , Andi Kleen , Christoph Hellwig , Steven Rostedt , Arnaldo Carvalho de Melo , Masami Hiramatsu , Thomas Gleixner , Anton Arapov Subject: Re: [RFC 0/6] uprobes: kill uprobes_srcu/uprobe_srcu_id Message-ID: <20120414205200.GA9083@redhat.com> References: <20120405222024.GA19154@redhat.com> <1334409396.2528.100.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1334409396.2528.100.camel@twins> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/14, Peter Zijlstra wrote: > > On Fri, 2012-04-06 at 00:20 +0200, Oleg Nesterov wrote: > > Hello. > > > > Not for inclusion yet, only for the early review. > > > > I didn't even try to test these changes, and I am not expert > > in this area. And even _if_ this code is correct, I need to > > re-split these changes anyway, update the changelogs, etc. > > > > Questions: > > > > - does it make sense? > > Maybe, upside is reclaiming that int from task_struct, downside is that > down_write :/ It would be very good not to have to do that. Yes, down_write() is pessimization, I agree. > Nor do I > really see how that works. > > > - can it work or I missed something "in general" ? > > So we insert in the rb-tree before we take mmap_sem, this means we can > hit a non-uprobe int3 and still find a uprobe there, no? Yes, but unless I miss something this is "off-topic", this can happen with or without these changes. If find_uprobe() succeeds we assume that this bp was inserted by uprobe. Perhaps uprobe_register() should not "ignore" -EXIST from install_breakpoint()->is_swbp_insn(), or perhaps we can add UPROBE_SHARED_BP. Oleg. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx162.postini.com [74.125.245.162]) by kanga.kvack.org (Postfix) with SMTP id 8BEEF6B004A for ; Sat, 14 Apr 2012 16:52:54 -0400 (EDT) Date: Sat, 14 Apr 2012 22:52:00 +0200 From: Oleg Nesterov Subject: Re: [RFC 0/6] uprobes: kill uprobes_srcu/uprobe_srcu_id Message-ID: <20120414205200.GA9083@redhat.com> References: <20120405222024.GA19154@redhat.com> <1334409396.2528.100.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1334409396.2528.100.camel@twins> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Ingo Molnar , Srikar Dronamraju , Andrew Morton , Linus Torvalds , Ananth N Mavinakayanahalli , Jim Keniston , LKML , Linux-mm , Andi Kleen , Christoph Hellwig , Steven Rostedt , Arnaldo Carvalho de Melo , Masami Hiramatsu , Thomas Gleixner , Anton Arapov On 04/14, Peter Zijlstra wrote: > > On Fri, 2012-04-06 at 00:20 +0200, Oleg Nesterov wrote: > > Hello. > > > > Not for inclusion yet, only for the early review. > > > > I didn't even try to test these changes, and I am not expert > > in this area. And even _if_ this code is correct, I need to > > re-split these changes anyway, update the changelogs, etc. > > > > Questions: > > > > - does it make sense? > > Maybe, upside is reclaiming that int from task_struct, downside is that > down_write :/ It would be very good not to have to do that. Yes, down_write() is pessimization, I agree. > Nor do I > really see how that works. > > > - can it work or I missed something "in general" ? > > So we insert in the rb-tree before we take mmap_sem, this means we can > hit a non-uprobe int3 and still find a uprobe there, no? Yes, but unless I miss something this is "off-topic", this can happen with or without these changes. If find_uprobe() succeeds we assume that this bp was inserted by uprobe. Perhaps uprobe_register() should not "ignore" -EXIST from install_breakpoint()->is_swbp_insn(), or perhaps we can add UPROBE_SHARED_BP. Oleg. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org