From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: Atomic operation for physically moving a page From: Dave Hansen In-Reply-To: <200406190103.i5J13WWr010687@turing-police.cc.vt.edu> References: <20040619003712.35865.qmail@web10904.mail.yahoo.com> <200406190103.i5J13WWr010687@turing-police.cc.vt.edu> Content-Type: text/plain Message-Id: <1087613632.4921.32.camel@nighthawk> Mime-Version: 1.0 Date: Fri, 18 Jun 2004 19:53:52 -0700 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Valdis.Kletnieks@vt.edu Cc: Ashwin Rao , linux-kernel , linux-mm List-ID: On Fri, 2004-06-18 at 18:03, Valdis.Kletnieks@vt.edu wrote: > On Fri, 18 Jun 2004 17:37:12 PDT, Ashwin Rao said: > > I want to copy a page from one physical location to > > another (taking the appr. locks). > > At the risk of sounding stupid, what problem are you trying to solve by copying > a page? Not only (as you note) could the page be referenced by multiple > processes, it could (conceivably) belong to a kernel slab or something, or be a > buffer for an in-flight I/O request, or any number of other possibly-racy > situations. You also have to make sure that the page is something who's physical address is allowed to change. Some stuff like DMA buffers, or a part of a hugetlb page might not even be valid to move. -- Dave -- 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: aart@kvack.org