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 ED3686B004D for ; Mon, 23 Apr 2012 03:41:00 -0400 (EDT) Message-ID: <1335166842.28150.92.camel@twins> Subject: Re: [RFC 0/6] uprobes: kill uprobes_srcu/uprobe_srcu_id From: Peter Zijlstra Date: Mon, 23 Apr 2012 09:40:42 +0200 In-Reply-To: <20120423072445.GC8357@linux.vnet.ibm.com> References: <20120414205200.GA9083@redhat.com> <1334487062.2528.113.camel@twins> <20120415195351.GA22095@redhat.com> <1334526513.28150.23.camel@twins> <20120415234401.GA32662@redhat.com> <1334571419.28150.30.camel@twins> <20120416214707.GA27639@redhat.com> <1334916861.2463.50.camel@laptop> <20120420183718.GA2236@redhat.com> <1335165240.28150.89.camel@twins> <20120423072445.GC8357@linux.vnet.ibm.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Srikar Dronamraju Cc: Oleg Nesterov , Ingo Molnar , 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 Mon, 2012-04-23 at 12:54 +0530, Srikar Dronamraju wrote: > * Peter Zijlstra [2012-04-23 09:14:00]: >=20 > > On Fri, 2012-04-20 at 20:37 +0200, Oleg Nesterov wrote: > > > Say, a user wants to probe /sbin/init only. What if init forks? > > > We should remove breakpoints from child->mm somehow.=20 > >=20 > > How is that hard? dup_mmap() only copies the VMAs, this doesn't actuall= y > > copy the breakpoint. So the child doesn't have a breakpoint to be > > removed. > >=20 >=20 > Because the pages are COWED, the breakpoint gets copied over to the > child. If we dont want the breakpoints to be not visible to the child, > then we would have to remove them explicitly based on the filter (i.e if > and if we had inserted breakpoints conditionally based on filter).=20 I thought we didn't COW shared maps since the fault handler will fill in the pages right and only anon stuff gets copied. > Once we add the conditional breakpoint insertion (which is tricky), How so? > we have > to support conditional breakpoint removal in the dup_mmap() thro the > uprobe_mmap hook (which I think is not that hard). Conditional removal > of breakpoints in fork path would just be an extension of the > conditional breakpoint insertion. Right, I don't think that removal is particularly hard if needed. -- 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