From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 70FA76B003D for ; Wed, 4 Feb 2009 10:45:27 -0500 (EST) Received: from localhost (smtp.ultrahosting.com [127.0.0.1]) by smtp.ultrahosting.com (Postfix) with ESMTP id EA38F82C33B for ; Wed, 4 Feb 2009 10:48:00 -0500 (EST) Received: from smtp.ultrahosting.com ([74.213.175.254]) by localhost (smtp.ultrahosting.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id oGWaDUBT32oL for ; Wed, 4 Feb 2009 10:48:00 -0500 (EST) Received: from qirst.com (unknown [74.213.171.31]) by smtp.ultrahosting.com (Postfix) with ESMTP id 074D482C518 for ; Wed, 4 Feb 2009 10:46:49 -0500 (EST) Date: Wed, 4 Feb 2009 10:39:19 -0500 (EST) From: Christoph Lameter Subject: Re: [RFC][PATCH] release mmap_sem before starting migration (Was Re: Need to take mmap_sem lock in move_pages. In-Reply-To: <20090204185501.837ff5d6.kamezawa.hiroyu@jp.fujitsu.com> Message-ID: References: <28631E6913C8074E95A698E8AC93D091B21561@caexch1.virident.info> <20090204183600.f41e8b7e.kamezawa.hiroyu@jp.fujitsu.com> <20090204184028.09a4bbae.kamezawa.hiroyu@jp.fujitsu.com> <20090204185501.837ff5d6.kamezawa.hiroyu@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Swamy Gowda , linux-kernel@vger.kernel.org, Brice.Goglin@inria.fr, "linux-mm@kvack.org" List-ID: On Wed, 4 Feb 2009, KAMEZAWA Hiroyuki wrote: > mmap_sem can be released after page table walk ends. No. read lock on mmap_sem must be held since the migrate functions manipulate page table entries. Concurrent large scale changes to the page tables (splitting vmas, remapping etc) must not be possible. -- 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/ . Don't email: email@kvack.org