Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757037AbZCLNj5 (ORCPT ); Thu, 12 Mar 2009 09:39:57 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756494AbZCLNjr (ORCPT ); Thu, 12 Mar 2009 09:39:47 -0400 Received: from x35.xmailserver.org ([64.71.152.41]:47613 "EHLO x35.xmailserver.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755922AbZCLNjq (ORCPT ); Thu, 12 Mar 2009 09:39:46 -0400 X-AuthUser: davidel@xmailserver.org Date: Thu, 12 Mar 2009 06:39:16 -0700 (PDT) From: Davide Libenzi X-X-Sender: davide@makko.or.mcafeemobile.com To: Andrew Morton cc: Eric Dumazet , Jeff Moyer , Avi Kivity , linux-aio , zach.brown@oracle.com, Benjamin LaHaise , Linux Kernel Mailing List , Christoph Lameter Subject: Re: [PATCH] fs: fput() can be called from interrupt context In-Reply-To: <20090311233903.f036027a.akpm@linux-foundation.org> Message-ID: References: <49B54143.1010607@redhat.com> <49B57CB0.5020300@cosmosbay.com> <49B875F7.3030305@cosmosbay.com> <49B87CFE.4000701@cosmosbay.com> <49B89B22.7080303@cosmosbay.com> <20090311224712.fb8db075.akpm@linux-foundation.org> <49B8A75E.6040409@cosmosbay.com> <20090311233903.f036027a.akpm@linux-foundation.org> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) X-GPG-FINGRPRINT: CFAE 5BEE FD36 F65E E640 56FE 0974 BF23 270F 474E X-GPG-PUBLIC_KEY: http://www.xmailserver.org/davidel.asc MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1309 Lines: 31 On Wed, 11 Mar 2009, Andrew Morton wrote: > > Take the time to check how fs/aio.c handle the fput(req->ki_filp) case > > (or read my 2nd patch, it should spot the thing) > > Well yes, a kludge like that seems a bit safer. > > It's somewhat encouraging that we're apparently already doing fput() > from within keventd (although how frequently?). There might be > problems with file locking, security code, etc from doing fput() from > an unexpected thread. And then there are all the usual weird problem > with using the keventd queues which take a long time to get discovered. Would it be a huge problem, performance-wise, to stop making ->f_count tricks in __aio_put_req, and always offload to fput_work the task of releasing the requests? If that's a huge problem, IMO the lower impact fix would be to use aio_fput_routine to loop into a second list, releasing the eventual eventfd file*. There's no need, IMO, to turn the whole fput() into IRQ-callable just for this case, when we can contain it into the particular KAIO+eventfd usage. - Davide -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/