From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752857Ab1H2H2O (ORCPT ); Mon, 29 Aug 2011 03:28:14 -0400 Received: from mail-ew0-f46.google.com ([209.85.215.46]:57609 "EHLO mail-ew0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751624Ab1H2H2I (ORCPT ); Mon, 29 Aug 2011 03:28:08 -0400 Date: Mon, 29 Aug 2011 09:28:00 +0200 From: Tejun Heo To: Oleg Nesterov Cc: rjw@sisk.pl, paul@paulmenage.org, linux-kernel@vger.kernel.org, arnd@arndb.de Subject: Re: [PATCH 12/16] freezer: clean up freeze_processes() failure path Message-ID: <20110829072800.GC16431@mtj.dyndns.org> References: <1313763382-12341-1-git-send-email-tj@kernel.org> <1313763382-12341-13-git-send-email-tj@kernel.org> <20110828180901.GD27032@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110828180901.GD27032@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 Sun, Aug 28, 2011 at 08:09:01PM +0200, Oleg Nesterov wrote: > This was copied from cancel_, yes. but what this > recalc_sigpending_and_wake() can or should do? > > It looks simply pointless. It can't clear TIF_SIGPENDING, > it can only do the unneeded/spurious wake_up(INTERRUPTIBLE). Yeah, I just copied it over. It seems it got confused between recalc_sigpending() and recalc_sigpending_and_wake() where the latter can't clear TIF_SIGPENDING. The signallable freezable kthread seems quite fragile. Once TIF_SIGPENDING is set, the only way for it to be cleared for a kthread is going through refrigerator and if freezing gets canceled before that happens, the kthread will have stuck TIF_SIGPENDING failing interruptible sleeps. We'll probably should move recalc_sigpending() to the top of refrigerator. But that said, I don't see any in-kernel user of set_freezable_with_signal(). Rafael, is there scheduled to be some new user of this API? It would be awesome if we can drop it. Thanks. -- tejun