From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail6.bemta7.messagelabs.com (mail6.bemta7.messagelabs.com [216.82.255.55]) by kanga.kvack.org (Postfix) with ESMTP id A2AE36B0092 for ; Mon, 13 Jun 2011 05:22:23 -0400 (EDT) Received: from d01relay07.pok.ibm.com (d01relay07.pok.ibm.com [9.56.227.147]) by e4.ny.us.ibm.com (8.14.4/8.13.1) with ESMTP id p5D90r8l029355 for ; Mon, 13 Jun 2011 05:00:53 -0400 Received: from d01av04.pok.ibm.com (d01av04.pok.ibm.com [9.56.224.64]) by d01relay07.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id p5D9MLfM753846 for ; Mon, 13 Jun 2011 05:22:21 -0400 Received: from d01av04.pok.ibm.com (loopback [127.0.0.1]) by d01av04.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id p5D9MKdr025023 for ; Mon, 13 Jun 2011 05:22:21 -0400 Date: Mon, 13 Jun 2011 14:44:47 +0530 From: Srikar Dronamraju Subject: Re: [PATCH v4 3.0-rc2-tip 2/22] 2: uprobes: Breakground page replacement. Message-ID: <20110613091447.GE27130@linux.vnet.ibm.com> Reply-To: Srikar Dronamraju References: <20110607125804.28590.92092.sendpatchset@localhost6.localdomain6> <20110607125835.28590.25476.sendpatchset@localhost6.localdomain6> <1307660612.2497.1774.camel@laptop> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <1307660612.2497.1774.camel@laptop> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Ingo Molnar , Steven Rostedt , Linux-mm , Arnaldo Carvalho de Melo , Linus Torvalds , Masami Hiramatsu , Hugh Dickins , Christoph Hellwig , Andi Kleen , Thomas Gleixner , Jonathan Corbet , Oleg Nesterov , Andrew Morton , Jim Keniston , Roland McGrath , Ananth N Mavinakayanahalli , LKML * Peter Zijlstra [2011-06-10 01:03:32]: > On Tue, 2011-06-07 at 18:28 +0530, Srikar Dronamraju wrote: > > +/** > > + * __replace_page - replace page in vma by new page. > > + * based on replace_page in mm/ksm.c > > + * > > + * @vma: vma that holds the pte pointing to page > > + * @page: the cowed page we are replacing by kpage > > + * @kpage: the modified page we replace page by > > + * > > + * Returns 0 on success, -EFAULT on failure. > > + */ > > +static int __replace_page(struct vm_area_struct *vma, struct page *page, > > + struct page *kpage) > > This is a verbatim copy of mm/ksm.c:replace_page(), I think I can > remember why you did this, but the changelog utterly fails to mention > why we need a second copy of this logic (or anything much at all). > __replace_page is not exactly a copy of replace_page. Its a slightly modified copy of replace_page. Here are the reasons for having this modified copy instead of using the replace_page. replace_page was written specifically for ksm purpose by Hugh Dickins. Also Hugh said he doesnt like replace_page to be exposed for other uses. He has plans for further modifying replace_page for ksm specific purposes which might not be aligned to what we are using. Further for replace_page, its good enuf to call page_add_anon_rmap() However for uprobes needs we need to call page_add_new_anon_rmap(). page_add_new_anon_rmap() will add the page to the right lru list. replace_page needs a reference to orig_pte while __replace_page doesnt need. I can add the same to Changelog but I am not sure it makes a good reading. Hence I had skipped it. -- Thanks and Regards Srikar -- 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