From mboxrd@z Thu Jan 1 00:00:00 1970 From: kamezawa.hiroyu@jp.fujitsu.com Message-ID: <28073963.1209598183931.kamezawa.hiroyu@jp.fujitsu.com> Date: Thu, 1 May 2008 08:29:43 +0900 (JST) Subject: Re: Re: Warning on memory offline (and possible in usual migration?) In-Reply-To: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-2022-jp" Content-Transfer-Encoding: 7bit References: <20080414145806.c921c927.kamezawa.hiroyu@jp.fujitsu.com> <20080422045205.GH21993@wotan.suse.de> <20080422165608.7ab7026b.kamezawa.hiroyu@jp.fujitsu.com> <20080422094352.GB23770@wotan.suse.de> <20080423004804.GA14134@wotan.suse.de> <20080429162016.961aa59d.kamezawa.hiroyu@jp.fujitsu.com> <20080430065611.GH27652@wotan.suse.de> <20080430001249.c07ff5c8.akpm@linux-foundation.org> <20080430072620.GI27652@wotan.suse.de> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: Nick Piggin , Andrew Morton , KAMEZAWA Hiroyuki , linux-mm@kvack.org, GOTO List-ID: > >One issue that I am still not clear on is (in particular for memory >offline) is how exactly to determine if a page is under read I/O. I >initially thought simply checking for PageUptodate would do the trick. > All troublesome case I found was "write". In my understanding, at generic bufferted file write, xxx_write_begin() -> write -> xxx_write_end() sequence is used. xxx_write_begin locks a page and xxx_write_end unlock it. (and xxx_write_end() set a page to be Uptodate in usual case.) So,it seems we can depend on that a page is locked or not. But it's complicated.... Thanks, -Kame -- 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