From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756021Ab1HWTpC (ORCPT ); Tue, 23 Aug 2011 15:45:02 -0400 Received: from mail-fx0-f46.google.com ([209.85.161.46]:44634 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755304Ab1HWTo4 (ORCPT ); Tue, 23 Aug 2011 15:44:56 -0400 Date: Tue, 23 Aug 2011 21:44:51 +0200 From: Tejun Heo To: Oleg Nesterov Cc: rjw@sisk.pl, menage@google.com, linux-kernel@vger.kernel.org, arnd@arndb.de Subject: Re: [PATCH 06/16] freezer: make exiting tasks properly unfreezable Message-ID: <20110823194451.GH2803@mtj.dyndns.org> References: <1313763382-12341-1-git-send-email-tj@kernel.org> <1313763382-12341-7-git-send-email-tj@kernel.org> <20110823155221.GB25808@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110823155221.GB25808@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Tue, Aug 23, 2011 at 05:52:21PM +0200, Oleg Nesterov wrote: > > @@ -915,6 +913,12 @@ NORET_TYPE void do_exit(long code) > > > > ptrace_event(PTRACE_EVENT_EXIT, code); > > > > + /* > > + * With ptrace notification done, there's no point in freezing from > > + * here on. Disallow freezing. > > + */ > > + current->flags |= PF_NOFREEZE; > > OK, but what PF_NOFREEZE actually means? > > Apart from "dont try to freeze" it means "no need to freeze", yes? Yes. > IOW, try_to_freeze_tasks() can succeed even if we have a lot of > exitinig task which can make some activity, say, disk i/o. Is this > correct? Hmmm... can it cause disk IOs after that point? I skimmed through and couldn't spot one (the original code made simliar assumption albeit a bit later). Thanks. -- tejun