From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030259AbWF0SmA (ORCPT ); Tue, 27 Jun 2006 14:42:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030281AbWF0Sl7 (ORCPT ); Tue, 27 Jun 2006 14:41:59 -0400 Received: from py-out-1112.google.com ([64.233.166.182]:7104 "EHLO py-out-1112.google.com") by vger.kernel.org with ESMTP id S1030259AbWF0Sl6 (ORCPT ); Tue, 27 Jun 2006 14:41:58 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references; b=inISVPvwwu6u62UezdyrdDU2I5tNYwHsgd66nukgpx68c10m44trYUn/xA9TNAEDGHU8dv7JFDm7ifyEFCtdOLV+8lZAlhGzNw1eqEHFKy+uhSi4IXFeknyq95RG2apcyPqfTMGaARDhzhBItZtcw/7ZPdHF7N1hXoj484I+XWI= Message-ID: <6bffcb0e0606271141o22077d69ya26fa6926e5524a1@mail.gmail.com> Date: Tue, 27 Jun 2006 20:41:58 +0200 From: "Michal Piotrowski" To: "Shailabh Nagar" Subject: Re: [PATCH] delay accounting taskstats interface: send tgid once locking fix Cc: akpm@osdl.org, "Arjan van de Ven" , linux-kernel@vger.kernel.org, mingo@elte.hu, balbir@in.ibm.com, jlan@engr.sgi.com In-Reply-To: <44A162F0.3060808@watson.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <200606261906.k5QJ6vCp025201@shell0.pdx.osdl.net> <1151421336.5217.28.camel@laptopd505.fenrus.org> <44A15483.30308@watson.ibm.com> <44A1576C.8090307@watson.ibm.com> <44A162F0.3060808@watson.ibm.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, On 27/06/06, Shailabh Nagar wrote: > Use irqsave variants of spin_lock for newly introduced tsk->signal->stats_lock > The lock is nested within tasklist_lock as part of release_task() and hence > there is possibility of a AB-BA deadlock if a timer interrupt occurs while > stats_lock is held. > > Thanks to Arjan van de Ven for pointing out the lock bug. > The patch conservatively converts all use of stats_lock to irqsave variant > rather than only the call within taskstats_tgid_free which is the function > called within tasklist_lock protection. > > Signed-off-by: Shailabh Nagar > Problem solved, thanks. Regards, Michal -- Michal K. K. Piotrowski LTG - Linux Testers Group (http://www.stardust.webpages.pl/ltg/wiki/)