From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753215AbaHSROf (ORCPT ); Tue, 19 Aug 2014 13:14:35 -0400 Received: from mail-wg0-f47.google.com ([74.125.82.47]:36385 "EHLO mail-wg0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751837AbaHSROd (ORCPT ); Tue, 19 Aug 2014 13:14:33 -0400 Date: Tue, 19 Aug 2014 20:14:26 +0300 From: Dan Aloni To: Benjamin LaHaise Cc: Linus Torvalds , security@kernel.org, linux-aio@kvack.org, linux-kernel@vger.kernel.org, Mateusz Guzik , Petr Matousek , Kent Overstreet , Jeff Moyer , stable@vger.kernel.org Subject: Re: Revert "aio: fix aio request leak when events are reaped by user space" Message-ID: <20140819171426.GA11811@gmail.com> References: <20140819163733.GA10132@gmail.com> <20140819165404.GD13858@kvack.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140819165404.GD13858@kvack.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 19, 2014 at 12:54:04PM -0400, Benjamin LaHaise wrote: > On Tue, Aug 19, 2014 at 07:37:33PM +0300, Dan Aloni wrote: > > Some testing I've done today indicates that the original commit broke > > AIO with regard to users that overflow the maximum number of request > > per IO context (where -EAGAIN is returned). > > > > In fact, it did worse - the attached C program can easily overrun the > > ring buffer that is responsible for managing the completed requests, > > and caused notification about their completion never to be returned. > > Argh, that would be a problem. > > ... > > This reverts commit b34e0e1319b31202eb142dcd9688cf7145a30bf6. > > Reverting isn't okay, as that reintroduces another regression. We need > to come up with a fix for this issue that doesn't reintroduce the other > regression for events reaped in user space. Let me have a look and see > what I can come up with... About the original regression you mention, is there a program you can indicate that reproduces it? On my setups, the regression testing in libaio was not able to detect the current regression too. -- Dan Aloni