Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753972Ab0DVXlB (ORCPT ); Thu, 22 Apr 2010 19:41:01 -0400 Received: from mail-gy0-f174.google.com ([209.85.160.174]:62120 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751314Ab0DVXk7 convert rfc822-to-8bit (ORCPT ); Thu, 22 Apr 2010 19:40:59 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=SI6fudYKtrQ47hh+Q0Uq1wasq9umULZ5bLB+FOu7jD3IEii/8xwl7HzLISKy2WTFxn cVBuLMobibuTXTkJROOrtaInBL3iTb+ujU5BKgjlxuRhKEZsvTmsskD8czLKsFl192Jy Xlc+Eph2O00naP/zhK2HDUbB5KLuGchqczUP0= MIME-Version: 1.0 In-Reply-To: <20100304201548.GA1341@elf.ucw.cz> References: <201003042026.30303.rjw@sisk.pl> <20100304201548.GA1341@elf.ucw.cz> Date: Thu, 22 Apr 2010 16:40:58 -0700 Message-ID: Subject: Re: [linux-pm] Is it supposed to be ok to call del_gendisk while userspace is frozen? From: Matt Reimer To: linux-kernel Cc: "Rafael J. Wysocki" , Alan Stern , Jens Axboe , Maxim Levitsky , linux-pm , Andrew Morton , Pavel Machek Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1157 Lines: 30 On Thu, Mar 4, 2010 at 1:15 PM, Pavel Machek wrote: > Hi! > >> > My thought exactly. ?This is the only approach that also solves the >> > following race: >> > >> > ? ? A driver is unloaded at the same time as a suspend starts. >> > >> > ? ? The writeback thread gets frozen. >> > >> > ? ? Then before the rmmod thread is frozen, it calls del_gendisk. >> > >> > Delaying things by means of a workqueue (or the equivalent) might also >> > work, but it doesn't seem as safe. ?For example, some important >> > writebacks might end up getting delayed until too late. > > Delaying writebacks during sleep should be ok... That's why we do > sync() after userspace is frozen -- nothing really important should be > waiting for writeback after that point. Has this been fixed, or has a consensus about how to fix this been achieved? I'm hitting the same problem and have some time to work on a fix. Matt -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/