From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S266217AbUHTKbx (ORCPT ); Fri, 20 Aug 2004 06:31:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S266204AbUHTKbw (ORCPT ); Fri, 20 Aug 2004 06:31:52 -0400 Received: from mx1.redhat.com ([66.187.233.31]:59565 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S268042AbUHTKbk (ORCPT ); Fri, 20 Aug 2004 06:31:40 -0400 Subject: Re: PF_MEMALLOC in 2.6 From: "Stephen C. Tweedie" To: Hugh Dickins Cc: Pete Zaitcev , Arjan van de Ven , Alan Cox , Greg KH , linux-kernel , Rik van Riel , Stephen Tweedie In-Reply-To: References: Content-Type: text/plain Content-Transfer-Encoding: 7bit Organization: Message-Id: <1092997872.1996.51.camel@sisko.scot.redhat.com> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.2 (1.2.2-5) Date: 20 Aug 2004 11:31:13 +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Thu, 2004-08-19 at 13:41, Hugh Dickins wrote: > Or would it solve the problem at hand, if it made itself PF_MEMALLOC > just while servicing a request from a PF_MEMALLOC? It's not the PF_* state of the caller who submitted the IO that matters, though --- it's the state of all threads _waiting_ on the IO, which may be different, and which can change even after the IO has begun. Eg. kswapd does a writepage, the writepage needs to allocate disk space, and in doing so tries to access a metadata block which is already undergoing IO from a different thread altogether. --Stephen