From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id 0904F8D0039 for ; Thu, 27 Jan 2011 05:28:58 -0500 (EST) Subject: Re: [RFC] [PATCH 2.6.37-rc5-tip 5/20] 5: Uprobes: register/unregister probes. From: Peter Zijlstra In-Reply-To: <20110127100157.GS19725@linux.vnet.ibm.com> References: <20101216095714.23751.52601.sendpatchset@localhost6.localdomain6> <20101216095817.23751.76989.sendpatchset@localhost6.localdomain6> <1295957744.28776.722.camel@laptop> <20110126075558.GB19725@linux.vnet.ibm.com> <1296036708.28776.1138.camel@laptop> <20110126153036.GN19725@linux.vnet.ibm.com> <1296056756.28776.1247.camel@laptop> <20110126165645.GP19725@linux.vnet.ibm.com> <1296061949.28776.1343.camel@laptop> <20110127100157.GS19725@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Date: Thu, 27 Jan 2011 11:29:36 +0100 Message-ID: <1296124176.15234.67.camel@laptop> Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org To: Srikar Dronamraju Cc: Ingo Molnar , Steven Rostedt , Linux-mm , Arnaldo Carvalho de Melo , Linus Torvalds , Ananth N Mavinakayanahalli , Christoph Hellwig , Masami Hiramatsu , Oleg Nesterov , Andrew Morton , SystemTap , Jim Keniston , Frederic Weisbecker , Andi Kleen , LKML , "Paul E. McKenney" List-ID: On Thu, 2011-01-27 at 15:31 +0530, Srikar Dronamraju wrote: >=20 > > You can, if only to wreck your thing, you can call mmap() as often as > > you like (until your virtual memory space runs out) and get many many > > mapping of the same file. > >=20 > > It doesn't need to make sense to the linker, all it needs to do is > > confuse your code ;-) >=20 > Currently if there are multiple mappings of the same executable > code, only one mapped area would have the breakpoint inserted. Right, so you could use it to make debugging harder.. > If the code were to execute from some other mapping, then it would > work as if there are no probes. However if the code from the > mapping that had the breakpoint executes then we would see the > probes. >=20 > If we want to insert breakpoints in each of the maps then we > would have to extend mm->uprobes_vaddr. >=20 > Do you have any other ideas to tackle this? Supposing I can get my preemptible mmu patches anywhere.. you could simply call install_uprobe() while holding the i_mmap_mutex ;-) > Infact do you think we should be handling this case? I'm really not sure how often this would happen, but dealing with it sure makes me feel better.. -- 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 policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org