From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752890Ab1H2Hbm (ORCPT ); Mon, 29 Aug 2011 03:31:42 -0400 Received: from mail-ew0-f46.google.com ([209.85.215.46]:49025 "EHLO mail-ew0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751624Ab1H2Hbi (ORCPT ); Mon, 29 Aug 2011 03:31:38 -0400 Date: Mon, 29 Aug 2011 09:31:31 +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 09/16] freezer: make freezing indicate freeze condition in effect Message-ID: <20110829073131.GD16431@mtj.dyndns.org> References: <1313763382-12341-1-git-send-email-tj@kernel.org> <1313763382-12341-10-git-send-email-tj@kernel.org> <20110828175601.GB27032@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110828175601.GB27032@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 On Sun, Aug 28, 2011 at 07:56:01PM +0200, Oleg Nesterov wrote: > > + /* leave FROZEN */ > > + spin_lock_irq(&freezer_lock); > > + current->flags &= ~PF_FROZEN; > > + spin_unlock_irq(&freezer_lock); > > What if freezing() is true again when we are going to clear > PF_FROZEN? > > In this case the 2nd try_to_freeze_tasks() can see this task > as already frozen and return success while it is going to run. Indeed, if we need to do if (frezing) goto retry; there. Will fix. Thanks. -- tejun