From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id A82016B0201 for ; Tue, 11 May 2010 12:15:36 -0400 (EDT) Date: Tue, 11 May 2010 17:15:16 +0100 From: Mel Gorman Subject: Re: [PATCH 2/2] mm,migration: Avoid race between shift_arg_pages() and rmap_walk() during migration by not migrating temporary stacks Message-ID: <20100511161516.GU26611@csn.ul.ie> References: <1272529930-29505-1-git-send-email-mel@csn.ul.ie> <1272529930-29505-3-git-send-email-mel@csn.ul.ie> <20100504094522.GA20979@csn.ul.ie> <20100510175654.GL26611@csn.ul.ie> <20100511151142.GS26611@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org To: Christoph Lameter Cc: Andrew Morton , Linux-MM , LKML , Minchan Kim , KAMEZAWA Hiroyuki , Andrea Arcangeli , Rik van Riel List-ID: On Tue, May 11, 2010 at 10:56:00AM -0500, Christoph Lameter wrote: > On Tue, 11 May 2010, Mel Gorman wrote: > > > Or just identify the temporary stack from the migration side instead of > > adding to the cost of exec? > > Adding one off checks to a generic mechanism isnt really clean > programming. Using the provided means of disabling a generic mechanism is. > Andrea's solution is likely lighter than yours as it is one kmalloc and an insertion into the VM as opposed to a page table walk with reference counting. Better yet, it exists as a patch that has been tested and it fits in with the generic mechanism by guaranteeing that rmap_walk finds all the migration PTEs during the second walk. The problem remains the same - that class of solution increases the cost of a common operation (exec) to keep a much less operation (migration) happy. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- 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